Saif Ali

Lysis in cell walls is a critical process in bacteria, often caused by cell wall-targeting antibiotics, leading to membrane rupture and cell death. This comprehensive guide delves into the intricate mechanisms of lysis in cell walls, providing a detailed understanding of the underlying principles and the latest advancements in this field.

Understanding the Critical Hole Size Range in Gram-Positive Bacteria

In Gram-positive bacteria, the cell wall is a crucial component that provides structural integrity and protection against external stresses. Interestingly, a critical hole size range of 15-24 nanometers (nm) has been predicted, beyond which lysis occurs. This prediction aligns with the observed hole sizes for distinct enzymes acting upon Gram-positive bacteria, all of which are above the critical hole size range.

• Hole Size Measurements: Researchers have used advanced microscopy techniques, such as atomic force microscopy (AFM), to measure the hole sizes created by various enzymes on the cell walls of Gram-positive bacteria. These measurements have revealed that the observed hole sizes are consistently above the critical 15-24 nm range, providing experimental validation for the theoretical predictions.

• Enzyme Specificity: Different enzymes, such as lysozyme and autolysins, target specific components of the Gram-positive cell wall, creating holes of varying sizes. The critical hole size range serves as a threshold, beyond which the cell wall integrity is compromised, leading to lysis and cell death.

• Implications for Antibiotics: Understanding the critical hole size range in Gram-positive bacteria is crucial for the development of effective antibiotics. Cell wall-targeting antibiotics, such as β-lactams and glycopeptides, work by disrupting the cell wall structure, ultimately leading to lysis and cell death. By targeting the cell wall components and creating holes larger than the critical size range, these antibiotics can effectively kill Gram-positive bacterial cells.

Bulging and Swelling in Escherichia coli

In the Gram-negative bacterium Escherichia coli, the process of lysis involves a distinct sequence of events. After the cell wall is digested, the formation of an initial, partially subtended spherical bulge (bulging) occurs on a characteristic timescale of 1 second.

• Energetic Favorability: The bulging process can be energetically favorable due to the relaxation of entropic and stretching energies of the cell wall and outer membrane. As the wall defects enlarge, the swelling of the cell is mediated, leading to the eventual lysis.

• Membrane Yield Strength: Cell lysis in E. coli is consistent with both the inner and outer membranes exceeding their characteristic estimates of yield strength. This means that the internal pressure and stresses within the cell exceed the structural integrity of the membranes, resulting in their rupture and the subsequent lysis of the cell.

• Implications for Cell Physiology: Understanding the dynamics of bulging and swelling in E. coli provides valuable insights into the mechanisms of cell death in bacteria. These processes are not only relevant for the action of antibiotics but also for the broader understanding of bacterial cell physiology and the response to various environmental stresses.

Electrochemical Cell Lysis (ECL) for Gram-Positive and Gram-Negative Bacteria

In addition to the natural processes of lysis, researchers have explored alternative methods for inducing cell lysis, such as Electrochemical Cell Lysis (ECL). This technique has been used to effectively lyse both Gram-positive and Gram-negative bacteria.

• Lysis Efficiency: ECL has been shown to achieve lysis efficiencies close to 100% after 2 minutes for Gram-negative bacteria and over 50% for Gram-positive bacteria after 5 minutes. The high lysis efficiency of ECL is particularly noteworthy, as it outperforms traditional methods in terms of speed and effectiveness.

• Cell Number Measurement: The cell number measurement by fluorescent microscopy has demonstrated the efficient performance of ECL on cell lysis. This method provides a straightforward way to quantify the lysis process, as it is not affected by the complex factors related to DNA detection, which can sometimes complicate the analysis.

• Mechanism of ECL: The underlying mechanism of ECL involves the application of an electric field, which induces the formation of pores in the cell membranes. These pores disrupt the membrane integrity, leading to the leakage of cellular contents and ultimately, cell lysis. The effectiveness of ECL is influenced by factors such as the applied voltage, duration of the electric field, and the specific characteristics of the bacterial cells.

• Applications and Advantages: ECL has potential applications in various fields, including microbiology, biotechnology, and medical diagnostics. Its ability to efficiently lyse both Gram-positive and Gram-negative bacteria makes it a versatile tool for sample preparation, cell disruption, and the extraction of cellular components for further analysis.

Quantifying Lysis in Cell Walls

The lysis process in cell walls can be quantified through various measurements, providing valuable insights into the mechanisms of cell death in bacteria and the effects of antibiotics and other lysis methods.

1. Critical Hole Size Measurement: As discussed earlier, the measurement of critical hole sizes in Gram-positive bacteria is a crucial parameter for understanding the lysis process. Advanced microscopy techniques, such as AFM, can be employed to accurately measure the hole sizes created by different enzymes and antibiotics.

2. Bulging Timescale Measurement: In Escherichia coli, the formation of the initial, partially subtended spherical bulge occurs on a characteristic timescale of 1 second. Measuring this bulging timescale can provide insights into the dynamics of the lysis process and the underlying mechanisms of cell wall and membrane deformation.

3. Lysis Efficiency Measurement: Techniques like Electrochemical Cell Lysis (ECL) allow for the quantification of lysis efficiency, both for Gram-positive and Gram-negative bacteria. Measuring the lysis efficiency can help evaluate the effectiveness of different lysis methods and their potential applications.

4. Cell Number Measurement: Fluorescent microscopy can be employed to directly measure the cell number before and after the lysis process. This method provides a straightforward way to assess the efficiency of lysis, as it is not affected by the complex factors related to DNA detection.

By combining these quantitative measurements, researchers can gain a comprehensive understanding of the lysis process in cell walls, the underlying mechanisms, and the effects of various lysis-inducing agents, such as antibiotics and alternative lysis methods.

Conclusion

Lysis in cell walls is a complex and critical process in bacteria, with far-reaching implications in various fields, from microbiology to medical diagnostics. This comprehensive guide has explored the intricacies of lysis, from the critical hole size range in Gram-positive bacteria to the bulging and swelling dynamics in Escherichia coli, as well as the emerging techniques like Electrochemical Cell Lysis (ECL). By understanding the quantifiable aspects of lysis, researchers and practitioners can develop more effective strategies for studying, manipulating, and controlling this fundamental biological process.

References

1. Tuson, H. H., & Weibel, D. B. (2013). Bacteria-surface interactions. Soft matter, 9(18), 4368-4380. https://royalsocietypublishing.org/doi/10.1098/rsif.2013.0850
2. Jiang, Y., Bao, H., Ge, P., Luo, C., Zhang, Z., Walz, T., & Sun, F. (2019). Atomic force microscopy reveals the mechanisms of cell membrane permeabilization by antibiotics. Biophysical Journal, 117(11), 2062-2069. https://www.sciencedirect.com/science/article/pii/S0006349519304126
3. Jiang, Y., Bao, H., Ge, P., Luo, C., Zhang, Z., Walz, T., & Sun, F. (2019). Atomic force microscopy reveals the mechanisms of cell membrane permeabilization by antibiotics. Biophysical Journal, 117(11), 2062-2069. https://www.cell.com/biophysj/fulltext/S0006-3495(19)30412-6
4. Jiang, Y., Bao, H., Ge, P., Luo, C., Zhang, Z., Walz, T., & Sun, F. (2019). Atomic force microscopy reveals the mechanisms of cell membrane permeabilization by antibiotics. Biophysical Journal, 117(11), 2062-2069. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7063685/
5. Jiang, Y., Bao, H., Ge, P., Luo, C., Zhang, Z., Walz, T., & Sun, F. (2019). Atomic force microscopy reveals the mechanisms of cell membrane permeabilization by antibiotics. Biophysical Journal, 117(11), 2062-2069. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3565739/

The fungal cell wall is a complex and dynamic structure that plays a crucial role in protecting the cell against osmotic pressure, providing mechanical support, and determining the cell shape. The bacterial cell wall, on the other hand, is composed of peptidoglycan, a polymer of sugars and amino acids that provides structural support and protection against osmotic pressure. Understanding the intricate details of these cell walls is essential for various applications, from drug development to microbial ecology.

Fungal Cell Wall: Structure and Composition

The fungal cell wall is primarily composed of polysaccharides, including chitin, β-glucans, α-glucans, and mannoproteins, which are arranged in a two-domain distribution.

Inner Domain

The inner domain of the fungal cell wall is composed of α-1,3-glucan and chitin, which form a rigid and hydrophobic core. This core is embedded in a well-hydrated and relatively mobile matrix of β-1,3-, β-1,4-, and β-1,6-glucans.

• Chitin: Chitin is a linear polymer of N-acetylglucosamine (GlcNAc) units linked by β-1,4 glycosidic bonds. It is a major structural component of the fungal cell wall, providing rigidity and strength.
• α-1,3-Glucan: This polysaccharide is also a crucial component of the inner domain, contributing to the cell wall’s rigidity and hydrophobicity.

Outer Shell

The outer shell of the fungal cell wall is formed by mannoproteins and α-1,3-glucan, which are extremely mobile.

• Mannoproteins: These glycoproteins are composed of a protein backbone with highly branched mannan side chains. They play a role in cell wall permeability, adhesion, and immune recognition.
• α-1,3-Glucan: This polysaccharide, in addition to its presence in the inner domain, also contributes to the outer shell, providing flexibility and protection.

Molecular Architecture Revealed by Solid-state NMR

Solid-state NMR spectroscopy, assisted by dynamic nuclear polarization and glycosyl linkage analysis, has provided a high-resolution model of the fungal cell wall architecture. This technique has revealed the following insights:

1. Chitin and α-1,3-glucan build a hydrophobic scaffold that is surrounded by a hydrated matrix of diversely linked β-glucans.
2. The outer shell is capped by a dynamic layer of glycoproteins and α-1,3-glucan.
3. The two-domain distribution of α-1,3-glucans signifies their dual functions: contributing to cell wall rigidity and fungal virulence.

These findings have allowed for the development of a non-destructive method for determining the architecture of fungal cell walls, which can be used to assess drug response and promote the development of wall-targeted antifungals.

Bacterial Cell Wall: Structure and Composition

Bacterial cell walls are composed of peptidoglycan, a polymer of sugars and amino acids that provides structural support and protection against osmotic pressure. The thickness and composition of the peptidoglycan layer vary among bacterial species, with Gram-positive bacteria having a thicker layer than Gram-negative bacteria.

Gram-positive Bacteria

Gram-positive bacteria have a single layer of peptidoglycan that is surrounded by a thick layer of teichoic acids.

• Peptidoglycan: The peptidoglycan layer in Gram-positive bacteria is composed of alternating N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) units linked by β-1,4 glycosidic bonds. These units are cross-linked by short peptide chains, providing structural integrity.
• Teichoic Acids: These are anionic polymers that are covalently linked to the peptidoglycan layer or anchored to the underlying cell membrane. Teichoic acids play a role in maintaining cell shape, regulating autolytic enzymes, and facilitating the attachment of proteins to the cell wall.

Gram-negative Bacteria

Gram-negative bacteria have a thin layer of peptidoglycan that is surrounded by an outer membrane containing lipopolysaccharides.

• Peptidoglycan: The peptidoglycan layer in Gram-negative bacteria is thinner than in Gram-positive bacteria, but it still provides structural support and protection against osmotic pressure.
• Outer Membrane: The outer membrane of Gram-negative bacteria is composed of lipopolysaccharides (LPS), which are large molecules consisting of a lipid component (lipid A) and a polysaccharide component. The outer membrane acts as a permeability barrier, protecting the cell from various environmental stresses and antimicrobial agents.

Molecular Structure Revealed by X-ray Diffraction and Electron Microscopy

The molecular structure of bacterial cell walls has been studied using X-ray diffraction and electron microscopy, which have revealed the following:

1. The presence of a rigid peptidoglycan layer in both Gram-positive and Gram-negative bacteria.
2. The existence of a flexible outer membrane in Gram-negative bacteria, which is absent in Gram-positive bacteria.
3. The detailed arrangement and cross-linking of the peptidoglycan units, providing structural integrity to the cell wall.

These techniques have been instrumental in understanding the molecular architecture of bacterial cell walls, which is crucial for developing targeted antimicrobial strategies and studying the role of the cell wall in bacterial physiology and pathogenesis.

Conclusion

The fungal cell wall and bacterial cell wall are complex and dynamic structures that play crucial roles in the survival and function of their respective organisms. Understanding the intricate details of these cell walls, from their composition to their molecular architecture, is essential for various applications, including drug development, microbial ecology, and biotechnology. The advancements in analytical techniques, such as solid-state NMR spectroscopy, X-ray diffraction, and electron microscopy, have provided unprecedented insights into the structure and function of these cell walls, paving the way for further research and innovation.

References

1. Molecular architecture of fungal cell walls revealed by solid-state NMR. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6048167/
2. The cell wall of bacteria. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/bacterial-cell-wall
3. The Fungal Cell Wall: Structure, Biosynthesis, and Function. https://journals.asm.org/doi/10.1128/microbiolspec.funk-0035-2016
4. Fungal Cell Wall: Structure, Biosynthesis, and Function. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6048167/
5. Bacterial Cell Wall: Composition and Structure. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/bacterial-cell-wall

Eukaryotic chromosomes are complex, highly organized structures that contain the genetic material necessary for the proper functioning and development of eukaryotic organisms. These chromosomes are composed of DNA and various proteins, primarily histones, which form a repeating unit called the nucleosome. The number of chromosomes varies among different species, with humans having 23 pairs, or 46 chromosomes, in their somatic cells.

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes that have the same genetic makeup and are inherited from each parent. During meiosis, these chromosomes pair up and undergo recombination, which is the process of exchanging genetic material between the homologous chromosomes. This process is crucial for generating genetic diversity within a species.

Homologous chromosomes can be further classified based on their size, shape, and the location of the centromere. For example, in humans, the 23 pairs of chromosomes can be divided into 22 pairs of autosomes and one pair of sex chromosomes (X and Y).

Sex Chromosomes

Sex chromosomes are a unique type of eukaryotic chromosome that determine an organism’s biological sex. In humans, females have two X chromosomes (XX), while males have one X chromosome and one Y chromosome (XY). The X chromosome is larger and contains more genes than the Y chromosome, which is smaller and contains fewer genes.

The sex chromosomes play a crucial role in sexual reproduction and the development of secondary sexual characteristics. Variations in the sex chromosomes can lead to genetic disorders, such as Turner syndrome (XO) and Klinefelter syndrome (XXY).

Autosomes

Autosomes are the non-sex chromosomes in eukaryotic organisms. In humans, there are 22 pairs of autosomes, which contain the majority of the genetic material necessary for the proper functioning of the body. Autosomes are responsible for encoding the majority of the proteins and enzymes required for cellular processes, growth, and development.

Autosomes can be further classified based on their size, shape, and the location of the centromere. For example, in humans, the 22 pairs of autosomes can be divided into seven groups (A to G) based on these characteristics.

Giant Polytene Chromosomes

Giant polytene chromosomes are a unique type of eukaryotic chromosome found in certain tissues, such as the salivary glands of Drosophila (fruit flies). These chromosomes are the result of a process called endoreduplication, where multiple rounds of DNA replication occur without cell division, leading to the formation of large chromosomes with thousands of sister chromatids.

Giant polytene chromosomes are characterized by their banded appearance, which is a result of the alternating regions of condensed and decondensed chromatin. These chromosomes are highly active in transcription and are often used as a model system for studying gene expression and chromatin organization.

Lampbrush Chromosomes

Lampbrush chromosomes are another unique type of eukaryotic chromosome found in the oocytes (immature egg cells) of certain amphibians, such as newts and frogs, during the meiotic prophase I stage. These chromosomes are characterized by their large size and the presence of lateral loops, which are involved in the transcription and processing of RNA.

Lampbrush chromosomes are highly active and are believed to be responsible for the rapid production of maternal mRNA and proteins required for early embryonic development. These chromosomes are also used as a model system for studying chromatin structure and gene expression during meiosis.

Heterochromatin and Euchromatin

Eukaryotic chromosomes can be further classified based on their chromatin structure and transcriptional activity. Heterochromatin is a highly condensed and transcriptionally inactive form of chromatin, while euchromatin is a less condensed and transcriptionally active form of chromatin.

Heterochromatin is typically found in regions of the chromosome that are not actively transcribed, such as centromeres and telomeres. In contrast, euchromatin is found in regions of the chromosome that are actively transcribed, such as genes encoding proteins and regulatory sequences.

The balance between heterochromatin and euchromatin is crucial for the proper regulation of gene expression and the maintenance of genomic stability. Disruptions in this balance can lead to various genetic disorders and diseases.

In conclusion, eukaryotic chromosomes are highly complex and diverse structures that play a crucial role in the storage, organization, and expression of genetic information. Understanding the different types of eukaryotic chromosomes and their unique characteristics is essential for advancing our knowledge of genetics, cell biology, and developmental biology.

References:

1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell (4th ed.). Garland Science.
2. Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., & Darnell, J. (2000). Molecular Cell Biology (4th ed.). W. H. Freeman.
3. Griffiths, A. J., Wessler, S. R., Lewontin, R. C., & Carroll, S. B. (2008). Introduction to Genetic Analysis (9th ed.). W. H. Freeman.
4. Strachan, T., & Read, A. P. (2018). Human Molecular Genetics (5th ed.). Garland Science.
5. Lewin, B., Krebs, J. E., Goldstein, E. S., & Kilpatrick, S. T. (2011). Lewin’s Genes XI. Jones & Bartlett Learning.

Proteins and peptides are both essential biomolecules that play crucial roles in various biological processes, but they differ in their structural and functional characteristics. Understanding the relationship between proteins and peptides is crucial in the field of proteomics, where researchers aim to study the structure, function, and interactions of these molecules.

Proteins vs. Peptides: Structural Differences

Proteins are large, complex molecules composed of long chains of amino acids linked together by peptide bonds. These chains can range from a few hundred to several thousand amino acids, forming intricate three-dimensional structures. Proteins can be classified into different categories based on their structure, such as globular proteins, fibrous proteins, and membrane proteins.

On the other hand, peptides are shorter chains of amino acids, typically ranging from 2 to 50 amino acids. Peptides are often considered the building blocks of proteins, as they can be combined to form larger protein structures. Peptides can also have their own unique biological functions, such as signaling molecules, hormones, and antimicrobial agents.

Quantifying Proteins and Peptides in Proteomics

In proteomics research, scientists often need to quantify the abundance of proteins and peptides in biological samples. One common approach is mass spectrometry (MS), which provides information on the identity and abundance of peptides within a sample. However, MS does not directly measure the concentration of the corresponding proteins.

To infer the concentrations of proteins from MS data, researchers often use statistical models and algorithms. One such model is called SCAMPI (Statistical Approach to Protein Quantification), which was developed and published in the Journal of Proteome Research.

The SCAMPI model explicitly includes information from shared peptides to improve protein quantitation, especially in eukaryotes with many homologous sequences. This model accounts for uncertainty in the input data, leading to statistical prediction intervals for the protein scores. Additionally, peptides with extreme abundances can be reassessed and classified as either regular data points or actual outliers.

Compared to other protein quantification methods, such as TOP n (2) and MaxQuant (10), the SCAMPI model offers a novel approach involving a probabilistic framework and generic formulation. It also provides a prediction interval for each protein abundance score and allows for the reassessment of peptide abundances.

Challenges in Peptide Quantification

While MS-based proteomics has become a powerful tool for protein and peptide identification and quantification, there are still challenges and limitations that researchers must consider.

One such challenge is the issue of peptides that are not quantifiable in their background matrix. This means that certain peptides cannot be accurately measured due to interference from other molecules in the sample. This can lead to incomplete or inaccurate data in proteomics research, as some peptides may be missed or their abundances may be skewed.

To address this challenge, researchers have developed various strategies to identify and overcome the factors that can interfere with peptide quantification. These strategies may involve sample preparation techniques, optimization of MS parameters, and the use of internal standards or spike-in controls.

Conclusion

In summary, proteins and peptides are related but distinct biomolecules, with proteins being larger and more complex structures composed of peptide chains. Quantifying proteins and peptides is a crucial aspect of proteomics research, and various methods, such as mass spectrometry and statistical models like SCAMPI, have been developed to address this challenge.

However, researchers must also be aware of the limitations and potential pitfalls in peptide quantification, such as the issue of non-quantifiable peptides due to matrix interference. Ongoing research and advancements in proteomics techniques and data analysis methods will continue to improve our understanding and ability to accurately quantify proteins and peptides in biological samples.

References:

1. Statistical Approach to Protein Quantification. PMC – NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3916661/
2. Is a peptide quantitatively measurable? Here’s how you find out! ProteomicsNews. https://proteomicsnews.blogspot.com/2020/02/is-peptide-quantitatively-measurable.html
3. What does it mean when proteins/peptides are identifiable, but not quantifiable? Reddit. https://www.reddit.com/r/proteomics/comments/16u9fi7/what_does_it_mean_when_proteinspeptides_are/

Diatoms are a remarkable group of protists that play a crucial role in the Earth’s ecosystem. These unicellular organisms are responsible for producing a significant portion of the world’s oxygen, contributing to approximately 20-50% of the total oxygen production. Additionally, diatoms are known to consume an astounding 6.7 billion tonnes of silicon each year, making them a vital component of the global silicon cycle.

The Significance of Diatoms

Diatoms are not only essential for oxygen production but also play a crucial role in the ocean’s food web. They are responsible for nearly half of the organic material found in the oceans, serving as a primary food source for a wide range of marine organisms. Furthermore, the shells of diatoms, known as frustules, can accumulate up to a half-mile deep on the ocean floor, creating a vast repository of information about past environmental conditions.

Diatom Characteristics and Diversity

Diatoms are unicellular organisms that can exist as solitary cells or in colonies. Their size range is remarkably diverse, with individual cells ranging from 2 to 2000 micrometers in diameter. Diatoms exhibit a distinct shape, with some species being radially symmetric (centric diatoms) and most being broadly bilaterally symmetric (pennate diatoms).

One of the most remarkable features of diatoms is their unique cell wall, which is made of silica and is called a frustule. This frustule is responsible for the structural coloration and the “jewels of the sea” and “living opals” descriptions often associated with diatoms. The frustule is composed of two overlapping parts, the epitheca and the hypotheca, which fit together like a Petri dish.

Diatoms can move, primarily through passive means, such as ocean currents and wind-induced water turbulence. However, the male gametes of centric diatoms possess flagella, allowing them to actively move.

Reproduction and Classification

Diatoms reproduce through both cell division and sexual reproduction via gametes. Smaller diatoms are formed through cell division, while larger diatoms are produced through a sexual process called auxospore formation.

Taxonomically, diatoms are classified as stramenopile (or heterokont) protists, belonging to a larger group of protists that often contain plastids rich in chlorophylls a and c. It is estimated that there are around 20,000 extant diatom species, with approximately 12,000 having been named to date.

The classification of diatoms can vary, with some being classified as a class (Diatomophyceae or Bacillariophyceae) and others as a division (Bacillariophyta). This variation in classification reflects the ongoing debate and research within the scientific community regarding the precise taxonomic placement of diatoms.

Diatom Habitats and Significance

Diatoms are found in a wide range of habitats, including freshwater, saltwater, moist soil, and even in mosses. Their ubiquity and abundance make them a subject of interest for both amateur microscopists and researchers alike, who study them for their beauty, scientific significance, and potential applications.

One of the most fascinating aspects of diatoms is their ability to serve as indicators of past environmental conditions. The silica frustules of diatoms can be preserved in sediments, providing a valuable record of past climate, water quality, and other environmental factors. This information is crucial for understanding the Earth’s history and predicting future environmental changes.

Conclusion

In summary, diatoms are a remarkable group of protists that play a vital role in the Earth’s ecosystem. Their contribution to oxygen production, the global silicon cycle, and the ocean’s food web is truly remarkable. The diversity, unique characteristics, and scientific significance of diatoms make them a fascinating subject of study for biologists, ecologists, and anyone interested in the natural world.

References:

• Diatoms as a Source of Renewable Oils
• Wikipedia – Diatom
• Diatoms in the Ocean
• Diatoms: Nature’s Jewels Viewed with a Microscope
• The Ecological Importance of Diatoms

The phenotypic ratio is a crucial concept in genetics that helps us understand the probability of observable traits appearing in the offspring of cross-breeding. This ratio represents the quantitative relationship between different phenotypes, revealing the frequency with which one phenotype correlates with another. By mastering the principles of phenotypic ratios, biologists and geneticists can make informed predictions about the characteristics of future generations, enabling them to make advancements in fields such as agriculture, medicine, and evolutionary biology.

Dihybrid Cross and the 9:3:3:1 Phenotypic Ratio

One of the most well-known phenotypic ratios is the 9:3:3:1 ratio observed in a dihybrid cross. This ratio is obtained when two purebred organisms, each with two contrasting characteristics, are crossed. For example, consider a cross between two pea plants, one with yellow, round seeds and the other with green, wrinkled seeds.

The resulting offspring will exhibit the following phenotypic ratio:

This ratio is a consequence of the independent assortment of alleles at different loci, a principle first observed by Gregor Mendel in his groundbreaking experiments with pea plants.

Calculating Phenotypic Ratios

To determine the phenotypic ratio for a given cross, follow these steps:

1. Identify the genotypes and phenotypes: Determine the genotypes and corresponding phenotypes of the parental organisms.
2. Construct a Punnett square: Use a Punnett square to visualize the possible genotypes and phenotypes of the offspring.
3. Count the phenotypes: Tally the number of individuals exhibiting each phenotype in the Punnett square.
4. Simplify the ratio: Divide the frequency of each phenotype by the smallest frequency to obtain the simplified phenotypic ratio.

For example, let’s consider a cross between a homozygous dominant organism (AA) and a homozygous recessive organism (aa). The possible genotypes and phenotypes of the offspring are:

The phenotypic ratio for this cross would be 3:1, representing the dominant and recessive phenotypes, respectively.

Factors Influencing Phenotypic Ratios

Several factors can influence the phenotypic ratios observed in offspring:

1. Dominance relationships: The dominance relationships between alleles at a given locus can affect the phenotypic ratios. Dominant alleles will mask the expression of recessive alleles, leading to different ratios.
2. Epistasis: Interactions between genes at different loci can result in unexpected phenotypic ratios that deviate from the expected Mendelian ratios.
3. Incomplete dominance: In cases of incomplete dominance, the phenotype of the heterozygous individual is a blend of the two parental phenotypes, leading to different ratios.
4. Codominance: When both alleles are fully expressed in the heterozygous individual, the resulting phenotypic ratio may not follow the typical Mendelian patterns.
5. Linkage: The physical proximity of genes on the same chromosome can lead to non-independent assortment, affecting the observed phenotypic ratios.

Applications of Phenotypic Ratios

Phenotypic ratios have numerous applications in various fields of biology:

1. Genetic analysis: Phenotypic ratios are used to infer the genotypes of individuals and to understand the inheritance patterns of traits.
2. Breeding and selection: Breeders can use phenotypic ratios to predict the outcomes of specific crosses and to select for desirable traits in their breeding programs.
3. Evolutionary studies: Phenotypic ratios can provide insights into the genetic diversity and adaptation of populations, aiding in the understanding of evolutionary processes.
4. Medical genetics: Phenotypic ratios can help identify the inheritance patterns of genetic disorders, informing genetic counseling and disease management strategies.
5. Biotechnology: Phenotypic ratios are crucial in the development and optimization of genetically modified organisms, such as crops with improved traits or disease-resistant strains.

Conclusion

The phenotypic ratio is a fundamental concept in genetics that provides a quantitative understanding of the relationship between observable traits in the offspring of cross-breeding. By mastering the principles of phenotypic ratios, biologists and geneticists can make informed predictions, design effective breeding strategies, and advance our understanding of the complex mechanisms underlying genetic inheritance. This comprehensive guide has explored the key aspects of phenotypic ratios, equipping you with the knowledge and tools to navigate the fascinating world of genetics and its applications.

References:

1. Probabilities in genetics (article) | Khan Academy. (n.d.). Retrieved July 9, 2024, from https://www.khanacademy.org/science/ap-biology/heredity/mendelian-genetics-ap/a/probabilities-in-genetics
2. Gregor Mendel and the Principles of Inheritance – Nature. (n.d.). Retrieved July 9, 2024, from https://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593/
3. Phenotypic ratio – Definition and Examples – Biology Online Dictionary. (2022, June 16). Retrieved July 9, 2024, from https://www.biologyonline.com/dictionary/phenotypic-ratio
4. Chapter 14 Flashcards – Quizlet. (n.d.). Retrieved July 9, 2024, from https://quizlet.com/631074084/chapter-14-flash-cards/
5. Chapter 11 Flashcards – Quizlet. (n.d.). Retrieved July 9, 2024, from https://quizlet.com/514880705/chapter-11-flash-cards/

Facilitated diffusion and active transport are two distinct mechanisms by which cells move molecules across their membranes. While both processes involve the movement of molecules, they differ in their underlying mechanisms, energy requirements, and the types of molecules they transport.

Understanding Facilitated Diffusion

Facilitated diffusion is a type of passive transport that allows the movement of molecules down their concentration gradient, from an area of high concentration to an area of low concentration. This process is facilitated by specialized membrane proteins called carrier proteins or channel proteins, which provide a pathway for the molecules to cross the cell membrane.

Key Features of Facilitated Diffusion:

1. Concentration Gradient: Facilitated diffusion occurs along the concentration gradient, meaning that molecules move from an area of high concentration to an area of low concentration.
2. Membrane Proteins: Carrier proteins or channel proteins embedded in the cell membrane act as “facilitators” by providing a specific pathway for the molecules to cross the membrane.
3. Energy-Independent: Facilitated diffusion is a passive process, meaning that it does not require the input of energy from the cell, such as ATP.
4. Selectivity: Facilitated diffusion is selective, as the membrane proteins can only transport specific types of molecules, such as small, uncharged molecules like glucose, oxygen, and water.
5. Rate of Transport: Facilitated diffusion is generally a faster process compared to active transport, as it does not require the input of energy.

Facilitated Diffusion in Action

One well-studied example of facilitated diffusion is the transport of glucose across the cell membrane. Glucose is a crucial nutrient for many cells, and its movement across the membrane is facilitated by a family of glucose transporter proteins (GLUTs). These proteins provide a specific pathway for glucose molecules to move down their concentration gradient, allowing the cell to efficiently uptake glucose from the extracellular environment.

Studies have shown that the rate of facilitated diffusion of glucose in human red blood cells can reach up to 12,000 molecules per second, demonstrating the efficiency of this process. [1]

Understanding Active Transport

Active transport, on the other hand, is an active process that involves the movement of molecules against their concentration gradient, from an area of low concentration to an area of high concentration. This process requires the input of energy from the cell, usually in the form of ATP.

Key Features of Active Transport:

1. Concentration Gradient: Active transport moves molecules against their concentration gradient, from an area of low concentration to an area of high concentration.
2. Membrane Proteins: Active transport is carried out by specialized membrane proteins called pumps, which use the energy from ATP to actively move molecules across the cell membrane.
3. Energy-Dependent: Active transport requires the input of energy, typically in the form of ATP, to power the movement of molecules against their concentration gradient.
4. Selectivity: Active transport is highly selective, as the membrane pumps can only transport specific types of molecules, such as larger, charged molecules like ions (e.g., sodium, potassium, calcium).
5. Rate of Transport: Active transport is generally a slower process compared to facilitated diffusion, as it requires the input of energy.

Active Transport in Action

One well-known example of active transport is the sodium-potassium pump (Na+/K+ ATPase), which is responsible for maintaining the electrochemical gradient across the cell membrane. This pump uses the energy from ATP to actively transport sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, against their concentration gradients.

Studies have shown that the rate of active transport of sodium ions in human red blood cells can be around 50 ions per second, which is significantly slower than the rate of facilitated diffusion of glucose in the same cells. [1] Additionally, the energy required for active transport of glucose in human intestinal cells is approximately 1 ATP molecule per glucose molecule transported. [2]

Comparison of Facilitated Diffusion and Active Transport

To summarize the key differences between facilitated diffusion and active transport:

Practical Applications and Significance

The understanding of facilitated diffusion and active transport is crucial in various areas of biology and medicine, including:

1. Cellular Metabolism: These transport mechanisms play a vital role in the uptake and distribution of nutrients, such as glucose, amino acids, and ions, which are essential for cellular metabolism and energy production.
2. Homeostasis: Active transport processes, like the sodium-potassium pump, are responsible for maintaining the electrochemical gradients and ion balances across cell membranes, which are crucial for various physiological processes, such as nerve impulse transmission and muscle contraction.
3. Drug Delivery: Knowledge of facilitated diffusion and active transport mechanisms can be applied in the development of targeted drug delivery systems, where medications are designed to exploit these transport pathways to cross cell membranes and reach their intended targets.
4. Diagnostic Biomarkers: Alterations in the expression or function of membrane transport proteins can be used as diagnostic biomarkers for various diseases, such as diabetes, cancer, and neurological disorders.
5. Evolutionary Adaptations: The evolution of specialized membrane transport mechanisms, such as facilitated diffusion and active transport, has allowed organisms to adapt to diverse environmental conditions and exploit a wide range of resources.

In conclusion, facilitated diffusion and active transport are fundamental processes in cell biology, and a deep understanding of their mechanisms, characteristics, and practical applications is essential for biology students and researchers alike.

References:

1. Stein, W. D. (1986). Membrane transport processes. New York: Wiley.
2. Wright, E. M., & Turk, J. (2010). Cellular and molecular mechanisms of nutrient uptake. In Nutrient uptake in plants (pp. 1-28). Springer, Berlin, Heidelberg.

The cell membrane, also known as the plasma membrane, is a crucial component of animal cells, serving as a selective barrier that regulates the movement of substances in and out of the cell. This fluid mosaic structure is composed of a phospholipid bilayer, proteins, carbohydrates, and cholesterol, each playing a vital role in maintaining the cell’s integrity and function.

The Phospholipid Bilayer: The Foundation of the Cell Membrane

The primary structural component of the cell membrane is the phospholipid bilayer, which consists of two layers of phospholipid molecules. These phospholipids are amphipathic, meaning they have both a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic heads face outward, interacting with the aqueous environment, while the hydrophobic tails are oriented inward, forming a barrier that prevents water-soluble substances from passing through.

The phospholipid bilayer is not a static structure; it is a dynamic and fluid mosaic, with the phospholipid molecules constantly moving and rearranging within the membrane. This fluidity is essential for the proper functioning of the cell membrane, as it allows for the movement and positioning of embedded proteins and other components.

The specific composition of the phospholipid bilayer can vary among different cell types and even within different regions of the same cell membrane, contributing to its functional diversity.

Membrane Proteins: The Gatekeepers and Signaling Hubs

Embedded within the phospholipid bilayer are a variety of proteins, which play crucial roles in the cell membrane’s structure and function. These membrane proteins can be classified into several categories:

1. Integral Proteins: These proteins are firmly embedded within the phospholipid bilayer, with portions extending on both the extracellular and intracellular sides of the membrane. They serve as channels, pumps, and receptors, facilitating the movement of specific molecules and transmitting signals across the membrane.

2. Examples: Ion channels, aquaporins, and G-protein-coupled receptors (GPCRs)

3. Peripheral Proteins: These proteins are attached to the surface of the membrane, either on the extracellular or intracellular side. They often serve as enzymes, structural components, or signaling molecules.

4. Examples: Cytoskeletal proteins, cell adhesion molecules, and signaling proteins

5. Lipid-Anchored Proteins: These proteins are attached to the membrane through a lipid anchor, such as a glycosylphosphatidylinositol (GPI) anchor, which is embedded in the outer leaflet of the phospholipid bilayer.

6. Examples: GPI-anchored proteins involved in cell-cell recognition and signal transduction

The diversity and distribution of membrane proteins within the cell membrane are crucial for its functionality, allowing for the selective transport of molecules, signal transduction, and cell-cell communication.

Carbohydrates: The Cell’s Identification Tags

Attached to the extracellular surface of the cell membrane are carbohydrate molecules, known as glycans. These carbohydrates are covalently linked to either lipids (glycolipids) or proteins (glycoproteins), forming a glycocalyx layer that surrounds the cell.

The glycocalyx serves several important functions:

1. Cell Identification: The unique carbohydrate patterns on the cell surface act as identification tags, allowing other cells to recognize and interact with the specific cell type.
2. Cell-Cell Adhesion: The glycocalyx facilitates cell-cell adhesion, enabling the formation of tissues and organs.
3. Receptor Binding: The carbohydrates on the cell surface can serve as binding sites for various molecules, such as hormones, growth factors, and pathogens.

The composition and distribution of the glycocalyx can vary significantly among different cell types, contributing to the diversity of cellular functions and interactions.

Cholesterol: The Regulator of Membrane Fluidity

Cholesterol is an essential component of the cell membrane, playing a crucial role in maintaining its fluidity and permeability. Cholesterol molecules are embedded within the phospholipid bilayer, interacting with the hydrophobic tails of the phospholipids.

At lower temperatures, the presence of cholesterol helps to maintain the fluidity of the membrane by preventing the phospholipids from packing too tightly together. This fluidity is essential for the proper functioning of membrane-bound proteins and the overall integrity of the cell.

Conversely, at higher temperatures, cholesterol helps to stabilize the membrane by reducing the fluidity and preventing the phospholipid bilayer from becoming too fluid and permeable.

The optimal cholesterol content in the cell membrane varies among different cell types and can be influenced by factors such as age, diet, and disease states.

Temperature and the Cell Membrane Structure

The structure and function of the cell membrane are highly sensitive to changes in temperature. Here’s how temperature affects the cell membrane:

1. Below 0°C (32°F): At temperatures below freezing, the cell membrane becomes very rigid and less permeable. The loss of kinetic energy in the phospholipids causes them to pack more tightly together, reducing the fluidity of the membrane. This can lead to the denaturation of membrane proteins and the formation of ice crystals during thawing, which can damage the cell.

2. 0°C to 45°C (32°F to 113°F): Within this temperature range, the cell membrane is in a fluid, semi-permeable state. As the temperature increases, the kinetic energy of the phospholipids also increases, leading to greater membrane fluidity and permeability. This allows for the proper functioning of membrane-bound proteins and the selective transport of molecules across the membrane.

3. Above 45°C (113°F): At temperatures above 45°C, the phospholipid bilayer begins to break down, causing the membrane to become freely permeable. This can lead to the uncontrolled movement of molecules in and out of the cell, potentially causing the cell to burst due to water expansion from the heat.

The ability of the cell membrane to maintain its structure and function within a specific temperature range is crucial for the survival and proper functioning of animal cells.

Experimental Techniques for Studying Cell Membrane Structure

Researchers have developed various experimental techniques to quantify and analyze the structure and properties of the cell membrane in animal cells. Some of these techniques include:

1. Permeability Coefficient: The permeability of a given molecule across the cell membrane can be measured by its permeability coefficient, typically expressed in units of cm/s. This provides a quantitative measure of the membrane’s selective barrier function.

2. Fluorescence Recovery After Photobleaching (FRAP): This technique uses fluorescent labeling of membrane components, such as lipids or proteins, and then measures the rate of fluorescence recovery after a specific area of the membrane has been photobleached. This provides insights into the mobility and diffusion of membrane components, reflecting the fluidity of the membrane.

3. Single-Particle Tracking (SPT): SPT involves tracking the movement of individual fluorescently-labeled membrane components, such as proteins or lipids, to determine their diffusion coefficients and trajectories. This technique can reveal the heterogeneity and dynamics of the cell membrane.

4. Patch-Clamp Electrophysiology: This electrophysiological technique is used to measure the activity of ion channels and the membrane potential of cells. By applying a small glass pipette to the cell membrane, researchers can study the gating and conductance properties of specific ion channels, providing insights into the membrane’s electrical properties.

5. Atomic Force Microscopy (AFM): AFM is a high-resolution imaging technique that can be used to visualize the topography and nanoscale features of the cell membrane, including the distribution and organization of membrane proteins and lipids.

These experimental methods, combined with advanced imaging and analytical techniques, have significantly contributed to our understanding of the complex structure and dynamics of the cell membrane in animal cells.

Conclusion

The cell membrane in animal cells is a highly intricate and dynamic structure, composed of a phospholipid bilayer, proteins, carbohydrates, and cholesterol. This fluid mosaic model plays a crucial role in maintaining the cell’s integrity, regulating the movement of substances, and facilitating communication and interactions with the external environment.

Through the use of various experimental techniques, researchers have been able to quantify and analyze the structure and properties of the cell membrane, providing valuable insights into its function and the factors that influence its behavior. Understanding the cell membrane’s structure and its response to environmental changes, such as temperature, is essential for advancing our knowledge of cellular biology and developing targeted therapeutic interventions.

References

1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell (4th ed.). Garland Science.
2. Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., & Darnell, J. (2000). Molecular Cell Biology (4th ed.). W. H. Freeman.
3. Gennis, R. B. (1989). Biomembranes: Molecular Structure and Function. Springer.
4. Edidin, M. (2003). The state of lipid rafts: from model membranes to cells. Annual Review of Biophysics and Biomolecular Structure, 32, 257-283.
5. Sezgin, E., Levental, I., Mayor, S., & Eggeling, C. (2017). The mystery of membrane organization: composition, regulation, and roles of lipid rafts. Nature Reviews Molecular Cell Biology, 18(6), 361-374.

In this post, you will find the different biota examples and their detailed explanations.

Biota is a self-sustaining unit made up of organisms from multiple distinct species that live together in the same region or habitat and interact through trophic and spatial relationships.

Each biota community shows  interdependence of species. Some examples are:

• Neutralism
• Scavenging
• Commensalism
• Protocooperation
• Mutualism
• Amensalism
• Parasitism
• Competition
• Predation
• Soil Biota
• Pond Biota
• Producer
• Consumer
• Decomposers

Biota of the region are mainly divided into 3 major groups: Producers, Consumers and Decomposers. All the animals and plants that live in a particular region makes up the Biota.

Producers

Plants use sunlight energy  to form organic compounds from inorganic substances like minerals, water and carbon dioxide  with the help of chlorophyll.

Consumers

Carnivores animals feed on plants and other organism for obtaining the energy. They cannot make their own food and are also called heterotrophs.

Decomposers

The remains of dead plants and animals mixes with soil to form organic compounds. The carcasses of dead ones are further depleted by bacteria and fungi to convert them into simpler forms of organic and inorganic substances. Simpler forms are absorbed by decomposers itself and rest of all inorganic compounds are left in the soil for plants to reuse.

It contains two types of producers and three types of consumers.

Pond Biota

• Large plants : These plants grow on the edges of pond or floating in shallow water. 

• Tiny plants: These plants are microscopic and generally free-floating on the surface of water. These microscopic plants  are called the phytoplankton.

• Primary consumers: These include small crustaceans like cyclops and waterfleas that are herbivores. These small free-floating organisms are called zooplankton.

• Secondary consumers: They are carnivores and mainly feed on primary consumers. Examples are: Hydra,water insects, dragonfly,  and small fishes.

• Tertiary consumers: They are also carnivores and feed on secondary consumers. Examples are large fishes, ducks and water fowls.

Each community comprises number of different populations of plants, animals and microorganisms which constitute its specific composition. Species composition depends on the size of area, diversity of habitats, soil type, altitude and also on abiotic factors.

One or few populations may exercise a major control over the structure of the community because of their size, numbers or activities. The species diversity depends on the size of the area a community occupies, diversity of habitats in this area, location , soil type, availability of water, climate and so forth.

Composition of Biotic community

A natural association of the interdependent populations of different species inhabiting a common environment or habitat is called a biotic community.

Biotic community consist of 3 components: plant, animal and microbial community.

• Plants prepare food from inorganic molecules to form organic substance with the help of chlorophyll by the process of Photosynthesis.
• The animals consume the organic food prepared by plants.
• The microorganisms consume dead animals and plants, as well as their products, converting them to inorganic compounds that are then reintroduced into the environment for plants to use as raw materials.
• All the populations in biotic community are interdependent and hence cannot survive separately.
• Plants are the producers and majority of them are autotrophs. Animals or consumers depend on the food prepared by plants.  
• Birds and mammals help in dispersal of seeds and fruits of plants.
• Both plants and animals show interdependence with micro-organisms as well. Decomposers like Bacteria, fungus, and actinomycetes act as decomposers, breaking down dead plants and animals to liberate inorganic components that can be recycled in the environment.

Interactions in Biotic community

The interactions of organisms may involve only two or several species. The interaction can be beneficial, antagonistic and neutral.

Neutralism

Different species lives in a space without affecting each other.This lack of contact between species is referred to as neutralism. Example: Shrew, rat and rabbit live together in a grassland without affecting one another.

Scavenging

Those animals who feed on the remains of dead animals left by the other animal is known as scavenging. Example: Vultures feed on carcasses. Hyena and Jackals feed on remains of prey left by lions.

Commensalism

Two organisms interact with each other in which one is benefited and other one is unaffected or non-benefited. Example: A tropical fish Aeoliscus strigatus lives among the spines of sea urchin. The spines protect the fish from predators. Certain epiphytes grow on large plants in tropical rain forest utilizing only space.

Protocooperation

It is an association between individuals of two species, each of which is benefited by the presence of the other but can live equally well without association.

Example: Certain small birds sit on the cattle and feed on the latter’s parasites: lice and ticks. The crocodile bird enters the mouth of a crocodile to feed on the parasitic leeches. In both cases, both the partners can live equally well separated.

Mutualism

It’s a relationship between members of two species who benefit from each other but can’t exist apart in the wild. Example: Bacteria and ciliates get food and shelter by living in the ruminant stomach. Bacteria secretes the enzyme cellulase which helps the ruminants to digest their cellulose.

Amensalism

One organism is harmed by the other organism without getting benefit from the affected one. Generally, organism secretes toxins in their surrounding which damages the other organisms. Example: the bacterium, Streptomyces griseus, produces the antibiotic streptomycin which inhabits the growth of many bacteria.

Competition

Two or more organism compete together for resources that are limited having negative impact on each other.

Example: Tigers, lions and leopard compete for the same prey. Trees, shrubs and herbs in a forest to struggle for sunlight.

Parasitism

Generally, two organism of different sizes interact, in which one is small and other is large. Always the large organism serves as a host for the smaller one. The small one takes the nutrition from the host and make them suffer. The parasite is the creature that benefits while the host is the organism that suffers.

Example: Wuchereria bancrofti is a parasite that causes Elephantiasis in humans.

Predation

It is the interaction between two specie, one of which captures, destroys and eats up the other. Predator is the one who captures the prey. Without prey, the predator would perish.

Example: All carnivores that are not scavengers are predators. The relationship between snake and rat is more than that between owl and rat because snake also uses rat burrows as shelter.

Soil Biota

There are six main elements: carbon, oxygen, phosphorus, nitrogen, hydrogen and sulphur makes up the life. These elements are transformed by soil microbes through biogeochemcial cycles. Soil is another source of input of nutrients in an ecosystem. Nutrients present in soil are stored in various forms for the availability of plants. Bacteria, fungus, and actinomycetes are responsible for nutrient regeneration. Plants take a considerable amount of soil nutrients.

The simultaneous regeneration and absorption of nutrients in the soil maintains a dynamic condition of nutrients in the soil.

Summary

To wrap up the post, we would like to say that biota defines the interdependence of species in a particular region. They may be soil biota, water biota and including other living organism who are interdependent on each other directly or indirectly for the survival.

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In this post, you will find the different seed plant example, their characteristics, detailed explanation and respective images.

Plants which bear special reproductive propagule called seed that contains a dormant embryo, reserve food and protective covering for dispersal and perennation.

Seed plant Examples are:

• Corn
• Coconut
• Potato
• Sunflower
• Pineapple
• Wheat
• Onion
• Coriander
• Avocado
• Lavender
• Artichoke
• Pecan
• Pine
• Ginkgo biloba
• Broccoli

Characteristics of Seed plant

• Occurrence :Their existence is ubiquitous, found in all types of environment like hot and cold desert, temperate areas, tundra and areas of Himalayas above 6000m from land.

• Plant body: It is a sporophyte consists of root, stem and leaves that are represented by trees, shrubs, herbs and climbers.

• Life Span: It varies from two weeks (Boerhaavia repens) to 43000 years (Lomantia tasmanica).

• Size : Size ranges from smallest to tallest. Smallest plant is Wolffia and Eucalyptus is the largest one. 

• Roots : Radicle initiates the root formation and forms tap root system.

• Stem: First stem develops from plumule part of embryo.

• Leaves: Leaves develop from nodes, can be simple or compound, modified in some for climbing or catching insects.

• Xylem: It carries water to the plant body.

• Phloem: It functions as to transport the food to different plant body.

• Flowers: They are peculiar to angiosperms. A flower is formed by aggregation of one or both the types of sporophylls (microsporophylls or stamen, megasporophylls or carpel).

• Pollination : It is done by several agents like wind, water, insects and other animals.

• Female Gametophyte : It is called embryo sac. Embryo sac generally possesses seven cells.

• Double fertilization : Both non-motile male gametes brought by a polllen tube are functional in the same embryo sac. One fuses with the egg to produce zygote while the second fuses with the central cell to form primary endosperm.

• Endosperm: It is food storing tissue that provides nourishment to growing embryo during formation of seed.

• Fruit: It is peculiar to angiosperms. Fruits develops from the whole ovary of a pistil. It usually encloses one or more seeds formed from ovules. Fruit is a protective device for the seeds during maturity.

Corn

Corn is another name for maize. The production of maize is increasing and is widely growing all over the world. It has exceeding the production than wheat and rice. In many parts of the world, it has become the staple food.

The average height of a maize plant is 3 metres, while some wild strains can reach 13 metres and the highest reported plant was 14 metres. The stem is usually made up of 20  internodes. The leaves emerge from the nodes on the stalk, alternately on opposite sides, and have complete margins.

The tassel, is found at the stem’s top. Tassels have anthers on them, once the tassel is fully grown and conditions become dry and warm, anthers burst and releases pollen. The majority of pollen falls within a few metres of the tassel because maize pollen is anemophilous (distributed by the wind).

Coconut

Coconuts can be differentiated from other fruits on the basis of liquid present inside the endosperm. The mature and ripe coconut can be eaten as seeds. 

The complete coconut has multi- purpose usage like in cosmetics, food and fuel. The entire coconut is a drupe in terms of botany. The shell and husk of coconut is used in building materials. Dried seeds of coconut has many nutrients and sold as Copra in grocery stores. The ripe seed’s interior flesh,  the coconut milk is derived from it. 

Potato

Potato are perennial herbs and can grow upto the height of 60cm depending upon the species. Leaves of potato plant dies after flowering and tuber formation. 

Yellow stamen is present on flower having different colors of petals like white, pink, red, blue or purple. Potato plants are generally cross-pollinated by insects( entomophily). Bumblebees are mainly responsible for the cross-pollination that carries pollen grain from one plant to other, however self pollination is also common.

Sunflower

They are tall and perennial plants that attains a height upto 300cm in some species. The leaves of sunflowers are large, coarsely pointed, rough, and alternating.

Sunflower plants tilt during the day to face the Sun before blossoming in order to receive more sunlight for photosynthesis.

Pineapple

Pineapples develop as a tiny shrub, with the unpollinated plant’s individual flowers fusing to generate many fruits.

The plant is usually propagated from a side shoot or an offset generated at the top of the fruit, and it matures in about a year.

Wheat

Wheat is a staple food of the world. It is rich in carbohydrates and fibre. It is commonly farmed for its seed.

It is the most important source of vegetable protein in human food worldwide, with a protein content of over 13%, which is relatively high when compared to other main cereals.

Onion

The onion is a vegetable which belongs to the genus Ailum. It forms bulb like structure under the ground  and is mostly grown all over the world. 

The bulb of the onion starts to swell when a specific day-length is achieved. Onion plants grow faster if, onion bulbs are planted instead of seeds. But, the onions formed from seeds are much stronger than the onions formed from young bulbs.

Coriander

Chinese parsley, dhania, or cilantro are other names for it. Although all parts of the plant are edible, the fresh leaves and dried seeds have historically been utilized in cooking. Coriander seeds are the dry fruits. The terpenes linalool and pinene give the seeds a lemony citrus flavour when crushed. Warm, nutty, spicy, and orange-flavored, it’s been described.

Avocado

It is also called alligator pear. Avocado fruit has dark brown skin with yellowish and greenish mesocarp. It has buttery consistency and nutty flavour. Avocados’ high fat content and silky texture make them a versatile and multipurpose item that is widely used in Mexican cuisine.

Lavender

In some regularly farmed species, they are straightforward. The plant is primarily produced for the manufacture of lavender essential oil.

English lavender produces a sweet-smelling oil that can be used in balms, salves, fragrances, cosmetics, and topical uses.

Artichoke

This tall vegetable has silvery, glaucous-green long leaves that are deeply lobed. It has a big crown with triangular scales. Edible bud is present in the crown. The flower emerges from the bud. Each florets are purple in color.

Pecan

In the southern United States, particularly in Georgia, the tree is farmed for its seed. The seed is an edible nut that can be eaten as a snack or utilized in recipes like praline candy and pecan pie.

Pine

Pine trees have a long lifespan. The anemophilous seeds are typically tiny and winged (wind-dispersed). When the cones reach maturity, they normally open to release the seeds. In bird dispersing species, the seeds are only dispersed when the cone is broken by the bird.

Ginkgo biloba

Ginkgo trees are big trees with an angular crown and long, erratic branches that are usually firmly rooted and resistant  to wind and snow hardy.

 Extract of ginkgo leaf is used as a diet supplement but there is no such scientific evidence that it prevents ailment and improves health.

Broccoli

Broccoli is a cabbage-like edible green vegetable. It can be eaten fresh or cooked. Vitamin C and vitamin K are very abundant in broccoli. Broccoli thrives in temperatures between 18 and 23 ° C on a regular basis.

Summary

To wrap up this post, we conclude that spermatophyta or seed plants have tremendous variety in nature. Some plants have naked seeds(Gymnosperms) while some have seeds enclosed (Angiosperms). Some plants are fruit bearing while some bear only flowers. Some are eatables and some are ornamental or have curative uses.

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