Sugaprabha Prasath

The process in which the mRNA molecule is synthesized from a DNA strand, it is called Transcription.

DNA transcription process is a complicated mechanism in which a DNA portion is converted or copied into a RNA molecule. The central dogma is a complicated process in which the DNA is transformed into a messenger RNA molecule and the messenger RNA is translated into a protein molecule.

Read more on Biosynthesis of Purines and Pyrimidines | An important part of cellular metabolism

What is the DNA transcription Process?

Every cell in every organism needs to be repaired and rejuvenated at one point of time.

DNA transcription is a process in which a segment of the DNA molecule is transcribed or converted or copied into a RNA molecule to be more precise the DNA molecule get copied to a messenger RNA molecule.

This is called the DNA transcription process.

DNA (segment) gets converted to a messenger RNA molecule.

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What is the DNA transcription process in prokaryotic organisms?

The DNA transcription process in prokaryotes is quite simple and it is of 3 stages or steps.

• Initiation
• Elongation
• Termination

DNA transcription process is a complicated mechanism in which a DNA portion is converted or copied into a RNA molecule-Messenger RNA with the help of an enzyme called RNA polymerase.

Initiation of the DNA transcription process:

• Initiation is a process in which the process starts.
• This process is initiated at a particular segment of DNA sequence which is commonly called the promoter region.
• The enzyme RNA polymerase incorporates Ribo- nucleotides to the template DNA strand.

Initiation consists have 3 types

• Closed complex
• Open complex
• Abortive initiation

Closed complex

• Closed complex is a stage in which the RNA polymerase adheres or bind to the promoter region of a DNA sequence.
• Like in DNA replication which uses the enzyme DNA polymerase, RNA polymerase does not need any enzyme like primase to initiate its desired process.

Open complex

• Open complex is the stage when the enzyme that is held together to the DNA sequence unwinds or release the double stranded DNA into a single strand at a certain or particular portion, this is called the open complex.
• The incorporation of rNTPs or the ribo-nucleotides to the template DNA will be done.
• The final product will be short stretches of RNA strand produced complementary to the template DNA.

Abortive initiation

• Abortive initiation is a process in which the sigma factors inhibit the RNA exit channel of RNA polymerase enzymes.

Elongation of the DNA transcription process:

• The sigma factor in the RNA polymerase will be freed from the complex and the elongation of the RNA strand complementary to the template DNA strand will be performed.
• Elongationis a process in which the biosynthesis of an RNA strand happens,the strand will be elongating by the addition of rNTPs or ribo- nucleotides.

Termination of the DNA transcription process:

There has to be an end point to end this transcription process and this is called the termination process or the end process.

The prokaryotic termination process will be of 2 types.

• Rho independent.
• Rho dependent

Rho independent:

• The other name of the Rho independent is  intrinsic terminators.
• This kind of termination  does not need any external proteins.

This consist of 2 sequence elements, they are

Short inverted repeats

Here are few examples of inverted repeats

Example – I

– – – – – – – – G T A G C A T T C G G – – – – – – – – – C C G A A T G C T A C – – – – – –

– – – – – – – – C A T C G T A A G C C – – – – – – – – – G G C T  T A C G A T G – – – – – – –

Example – II

– – – – – – – – T A G C A T T C G G T- – – – – – – – A C C G A A T G C T A- – – – – – –

– – – – – – – – A T C G T A A G C C A- – – – – – – – T G G C T T A C G A T- – – – – – –

Example – III

– – – – – – – – G T A G C A T T C G G T- – – – – – – – A C C G A A T G C T A C- – – – – – –

– – – – – – – – C A T C G T A A G C C A- – – – – – – -T G G C T T A C G A T G- – – – – – –

So from the above examples, we can see that in the 2 strands of the DNA the nitrogenous bases are repeated in the inversion form on its complementary strand with minimal gaps (having other nitrogenous bases).

A T rich sequence

– – G T A G C A T T C G G – – – – – – – – C C G A A T G C T A C – – – – A A A A

– – C A T C G T A A G C C – – – – – – – – G G C T  T A C G A T G – – – – T T T T 

• A T rich sequence is a sequence in which continuously the strand has adenine that complements thymine or vice versa.
• First the inverted repeated sequences will be present and then they are followed by AT rich sequences.
• Now due to this inverted sequence and AT rich sequence at the terminal point, a hairpin or inverted U shape like structure will be produced by base pairing in the same strand which then stops the complete process.
• Then A T rich sequence becomes A U rich sequence as in RNA thymine is replaced by uracil.
• Among all the base pairs ( A – T ; T – A ; C – G ; G – C ; A – U; U – A), the weakest pair will be  A-U or U – A.
• Due to this weak pairing element, this is the terminal point and the RNA will be released or freed and the process is terminated.

Rho dependent:

• The Rho dependent termination process will need a Rho protein to end the process of transcription.
• This Rho protein is a hexameric protein and needs Adenosine triphosphate molecules for its action.
• This Rho protein adheres to the RNA sequence which has more number of cytosine or C, which are also known as Rho utilization sites or the RUT site.

– – – – – – – – C C C C C C – – – – – – – 

• This will eventually become the Rho sensitive pause site and unwinds the region.
• Now the final product will be a strand of RNA that is let out from the template DNA, this is the process of prokaryotic DNA transcription.

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What is the DNA transcription process in eukaryotic organisms?

The transcription process is quite complex in eukaryotic organisms.

The eukaryotic organism transcription has 3 steps: Initiation, elongation and termination.

Initiation of the eukaryotic transcription process:

• In this process, 3 RNA polymerase (RNA polymerase I,RNA polymerase II,RNA polymerase III) is used. More importantly RNA polymerase II contributes more in the eukaryotic transcription process.
• There are few transcription factors involved which are called the TF.

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The types of TFs are

• TFIID
• TFIIA
• TFIIB
• TFIIF
• TFIIE
• TFIIH

The eukaryotic promoter is about 40 nucleotides long located in the upstream and downstream in the sequence.

TFIID :

• Initially, the transcription factor TFIID binds to the TATA element of the promoter.
• TFIID produces a protein called the TATA binding protein OR TBP and this protein binds to the TATA sequence resulting in the bending of the sequences to about 80 degree.
• This bending helps in the adhesion of other factors like TFIIA and TFIIB.

TFIIA :

TFIIA aids in stabilizing the binding of TFIID into the promoter sequences.

TFIIB :

• TFIIB interacts with TBP or the TATA binding proteins at the promoter region downstream to the sequence.
• The TFIIB aids in the recruitment of the RNA polymerase II on the promoter as the RNA polymerase can not bind on its own.

TFIIF :

TFIIF aids in the binding of RNA polymerase II into the promoter sequence.

TFIIE :

TFIIE helps to start the preinitiation complex.

TFIIH

• TFIIH is a large complex consisting of 9 subunits, 2 subunits have ATPase activity which provides energy and it acts like helicase and unwinds the DNA.
• This results- From preinitiation complex to open complex.

The other 7 subunits acts as a kinase activity and binds to the RNA polymerase tail and moves to the next step elongation.

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Elongation of the eukaryotic transcription process:

• The elongation factors are the components that aid in the elongation process.
• TFEB is a kinase protein and undergoes phosphorylation which stimulates elongation and TFIIS is like a catalyst which aids in the fastening of the elongation process by not letting the RNA polymerase to pause.
• 5′ capping is a process in which certain enzymes add and delete few compounds that aid in the initiation of the translation process.

Termination of the eukaryotic transcription process:

• The RNA polymerase reaches the end point, 2 proteins called the CstF and CPSF interact with the transcription complex and cleaves the messenger RNA from the complex.
• Every component from the complex dissociates.
• CPSF then adds or recruits poly A polymerase which adds about 200 bases of adenine at the 3 ‘ end resulting in the poly A tail by utilizing ATP and the process stops.

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Transcription in DNA is the process in which a portion of the DNA is transcribed or copied into a RNA molecule.

The DNA transcription types- There are two types of DNA transcription, they are the prokaryotic transcription of DNA and the Eukaryotic transcription of DNA. Both are majorly the same but the prokaryotic transcription of DNA is quite simple than the eukaryotic which is complex by nature. 

This article completely focuses on eukaryotic and prokaryotic transcription.

Read more on Biosynthesis of Purines and Pyrimidines | An important part of cellular metabolism

What are the DNA transcription types in prokaryotes?

The DNA transcription process in prokaryotes is simple and is of only one type that consists of 3 steps.

Transcription in DNA is the process in which a portion of the DNA is transcribed or copied into a Messenger RNA or mRNA strand with the help of an enzyme called RNA polymerase.

This process is initiated at a specific DNA sequence which is commonly called the promoter region.

The enzyme RNA polymerase adds Ribo- nucleotides to the template DNA strand.

Initiation:

Initiation consists have 3 types

• Closed complex
• Open complex
• Abortive initiation

Closed complex

• Closed complex is when the RNA polymerase attaches to the promoter region of DNA sequence.
• Like in DNA replication- DNA polymerase, RNA polymerase does not require any enzyme like primase to initiate its desired process.

Open complex

• Open complex happens when the enzyme that is bound to the DNA sequence unwinds the double stranded DNA at a certain or specific portion, this is called the open complex.
• Now the addition of rNTPs or the ribo-nucleotides to the template DNA will be done.
• The end product will be short stretches of RNA strand produced complementary to the template DNA.

Abortive initiation

Abortive initiation is a process in which the sigma factors block the RNA exit channel of RNA polymerase enzymes.

Elongation:

• The sigma factor in the RNA polymerase will be released and the elongation of the RNA strand complementary to the template DNA strand is done.
• The elongation is a process in which the RNA strand will keep on synthesizing, that is the strand will be elongating with the addition of rNTPs.

Termination:

There has to be a stop point to end this transcribing process and this is called the termination process.

In prokaryotes, the termination process will be of 2 types.

• Rho independent
• Rho dependent

Rho independent:

• This is also called the intrinsic terminators.
• This type of termination  does not require any external proteins.
• This consist of 2 sequence elements, they are

Short inverted repeats

Examples of inverted repeats are

Example – I

– – – – – – – – G T A G C A T T C G G – – – – – – – – – C C G A A T G C T A C – – – – – – –

– – – – – – – – C A T C G T A A G C C – – – – – – – – – G G C T  T A C G A T G – – – – – – –

Example – II

– – – – – – – – T A G C A T T C G G T- – – – – – – – A C C G A A T G C T A- – – – – – –

– – – – – – – – A T C G T A A G C C A- – – – – – – – T G G C T T A C G A T- – – – – – –

Example – III

– – – – – – – – G T A G C A T T C G G T- – – – – – – – A C C G A A T G C T A C- – – – – – –

– – – – – – – – C A T C G T A A G C C A- – – – – – – -T G G C T T A C G A T G- – – – – – –

A T rich sequence

– – G T A G C A T T C G G – – – – – – – – C C G A A T G C T A C – – – – A A A A

– – C A T C G T A A G C C – – – – – – – – G G C T  T A C G A T G – – – – T T T T 

• The inverted repeated sequences are always followed by AT rich sequences.
• Now due to this inverted sequence and AT rich sequence at the end, a hairpin like structure will be formed by pairing of the bases in the same strand which then halts the complete process.
• Finally the A T rich sequence becomes A U rich sequence as in RNA thymine is replaced by uracil.
• Of all the base pairs ( A – T ; T – A ; C – G ; G – C ; A – U; U – A), A-U or U – A is the weakest pair.
• Due to this weak element, this is the end and the RNA will be released and the process is terminated.

Rho dependent:

• This type of termination process requires a Rho protein to terminate the process of transcription.
• This Rho protein is a hexameric protein and requires ATP molecules for its action.
• This Rho protein binds to the RNA sequence rich in C or Cytosine, which are also known as Rho utilization sites or the RUT site.
• Example: – – – – – – – – C C C C C C – – – – – – – 
• This will eventually become the Rho sensitive pause site and unwinds the region.
• Now the end product will be a strand of RNA that is released from the template DNA, this is the process of prokaryotic DNA transcription.

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What are the types of transcription process in eukaryotes?

In eukaryotes, the DNA transcription is quite more complex than the prokaryotes, but yes the basic concept and steps are quite similar.

In eukaryotes, the transcription of DNA is done by 3 type of enzymes called RNA Polymerase I,RNA Polymerase II and RNA Polymerase III.

• RNA Polymerase- I
• RNA Polymerase- II
• RNA Polymerase- III

The RNA polymerase- I is present in nucleolus and works on the 28S, 18S, and 5.8S rRNA genes.

The RNA polymerase- II is present on the nucleoplasm and works on the protein coding genes.

The RNA polymerase III is also seen in nucleoplasm and works on tRNA, 5S rRNA, U6 snRNA, and the 7S RNA and few more other factors.

Transcription in eukaryotes happens inside the nucleus organelle and mRNA leaves the nucleus and enters the cytoplasm for the translation process.

The initiation of RNA synthesis by RNA polymerase using the complementary DNA strand is done by the appearance and recognition of a promoter site on the 5’ side of the transcriptional start site.

The elongation process proceeds and the mRNA strand will be synthesized using the targeted enzyme.

The termination process will be initiated at one point in the cleaved site and thus the process is stopped.

Though the mRNA strand is produced, it has both the coding sequence and non coding sequence on it. So it has to undergo another process called the post transcriptional modification in which the non coding sequence will be removed.

This is the summary of the eukaryotic transcription of DNA including the process and the types,enzymes used.

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What are DNA transcription types in Bacteria?

The DNA transcription process in bacteria is so simple and it consists of only one type with 3 steps.

• Initiation
• Elongation
• Termination

Initiation:

• In bacteria, this process is initiated at a specific DNA sequence which is commonly called the promoter region.
• The enzyme RNA polymerase adds Ribo- nucleotides to the template DNA strand.

Initiation consists have 3 types

• Closed complex
• Open complex
• Abortive initiation

Closed complex and open complex has already discussed in the same article, please click here to read more on the closed complex and open complex.

Abortive initiation

Abortive initiation in bacteria is a process in which the sigma factors block the RNA exit channel of RNA polymerase enzymes.

Elongation:

• The sigma factor in the RNA polymerase will be released and the elongation of the RNA strand complementary to the template DNA strand is done.
• The elongation is a process in which the RNA strand will keep on synthesizing, that is the strand will be elongating with the addition of rNTPs.

Termination:

• There has to be a stop point to end this transcribing process and this is called the termination process.
• In bacteria, the termination process will be of 2 types.

• Rho independent.
• Rho dependent

Rho independent:

• This is also called the intrinsic terminators.
• This type of termination  does not require any external proteins.
• This consist of 2 sequence elements, they are

Short inverted repeats

Example of inverted repeats are

– – – – – – – – G T A G C A T T C G G – – – – – – – – – C C G A A T G C T A C – – – – – – –

– – – – – – – – C A T C G T A A G C C – – – – – – – – – G G C T  T A C G A T G – – – – – – –

A T rich sequence

– – G T A G C A T T C G G – – – – – – – – C C G A A T G C T A C – – – – A A A A

– – C A T C G T A A G C C – – – – – – – – G G C T  T A C G A T G – – – – T T T T 

• The inverted repeated sequences are always followed by AT rich sequences.
• Now due to this inverted sequence and AT rich sequence at the end, a hairpin like structure will be formed by pairing of the bases in the same strand which then halts the complete process.
• Finally the A T rich sequence becomes A U rich sequence as in RNA thymine is replaced by uracil.
• Of all the base pairs ( A – T ; T – A ; C – G ; G – C ; A – U; U – A), A-U or U – A is the weakest pair.
• Due to this weak element, this is the end and the RNA will be released and the process is terminated.

Read more on Is Fungi Multicellular Or Unicellular: Why, How And Detailed Insights And Facts

Rho dependent:

• This type of termination process requires a Rho protein to terminate the process of transcription.
• This Rho protein is a hexameric protein and requires ATP molecules for its action.
• This Rho protein binds to the RNA sequence rich in C or Cytosine, which are also known as Rho utilization sites or the RUT site. Example: – – – – – – – – C C C C C C – – – – – – – 
• This will eventually become the Rho sensitive pause site and unwinds the region.
• Now the end product will be a strand of RNA that is released from the template DNA, this is the process of bacterial DNA transcription.

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DNA replication is a process in which the DNA makes its own copies or duplicates itself during the process of the division of cells. This DNA replication is a semiconservative process.

Now, what is the semiconservative DNA replication process and what are the steps involved in it. The DNA replication process includes Initiation, Elongation and termination. It starts from the recognition of the site of the replication and includes various steps and concludes it by joining the DNA fragment molecules.

This article will focus on the detailed information on each and every part of the DNA replication process.

So, we know that DNA is a genetic material which carries the genetic information and passes from one generation to another.

DNA is a double stranded organic molecule consisting of a pentose sugar molecule, phosphate molecule and 4 nitrogenous bases paired. Adenine pairs with thymine and cytosine with guanine.

Each of these molecules have the genes that code for a specific amino acid and provide the genetic information.

What is a Semiconservative DNA replication process?

We know that DNA replication is a process in which 1 strand replicates itself and makes copies out of it.

DNA is a double strand and has a nitrogenous base( A, T, G, C), a pentose sugar molecule- Deoxyribose sugar, a highly negative phosphate molecule. So during replication of the initial strand of DNA, one strand is retained and the other strand is made by adding the specific nucleotides to it.

So one is the newly formed strand of DNA (Addition of nucleotides) and the other strand is the retained old DNA strand which is called the template strand.

Example: The template strand of DNA is

A T T G C A T A G G G G C C T T T A A C C T G G  C A T A G G T T T A A A C C C G G G G A G G G G C C T T T A A C C T G G  C A T A G G

The newly formed complementary strand of DNA will be

T A A C G T A T C C C C G G A A A T T G G A C C G T A T C C A A A T T T G G G C C C C T C C C C G G A A A T T G G A C C G T A T C C

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What are the steps in the semiconservative DNA replication process?

The semiconservative DNA replication process includes 3 steps.

• Initiation
• Elongation
• Termination

Initiation:

• This is the process in which the DNA replication starts or initiates.
• The enzyme called helicase that is responsible for the recognition of the ORIC– Origin of replication binds to the DNA strand and unwinds or separates the double stranded DNA molecule.
• The end product of the step/ stage/ phase is the 2 strands of the double stranded DNA becoming 2 separate DNA strands, but not completely.
• The half of the strand remains as the double strand as they do not participate at that positive moment, thus producing a fork-like structure called the replication fork.

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Elongation:

• Addition of RNA nucleotides by the primer takes place here to the template DNA strand.
• Another enzyme called Primase produces a small strand of RNA to which the next enzyme identifies and binds.
• The 3’ to 5’ direction of the strand is called the leading strand.
• The 5’ to 3’ direction of the strand is called the lagging strand.
• This addition of nucleotides is done by a specific enzyme called the DNA polymerase which adds the nucleotide that complements the template DNA.
• The DNA polymerase does not have the capacity to produce or synthesize a new strand, it can only add to a pre existing strand.
• Finally, the RNA nucleotides will be replaced by DNA nucleotides by enzymes called exonucleases FEN1 and RNase H.
• So when Adenine is present, thymine is added and guanine is present, cytosine is added- vice versa.

Termination:

• Now, the synthesis of new strands must stop at a point. When the termination point has reached, the DNA polymerase stops the addition of nucleotides.
• The DNA polymerase does not have the ability to create a bond in between to combine it.
• The enzyme ligase combines the strand by creating a phospho-di-ester bond into the DNA molecule thus that strands get combined.

Read More on Adenosine nucleoside and nucleoside phosphoramidite | Overview of important aspects

Summary of steps in the semiconservative DNA replication process:

The actual and the well known steps in the semiconservative DNA replication is the Initiation, elongation, termination process. The much more simplified version is

• Recognition of the site or origin of replication
• Dissociation or unwinding of DNA strands.
• Addition of the nucleotides
• Synthesis of a new strand of DNA
• Termination of the synthesis process
• Combining of the strands by enzymatic process

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So 1 double strand of DNA becomes 2 double stranded DNA molecules Each strand has 1 template and one newly synthesized dna that complements the Template DNA.

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What are the enzymes that are responsible for the Semiconservative DNA replication process?

• DNA Helicase Enzyme – DNA Helicase aids in the unwinding of the double stranded DNA.
• Primase Enzyme – Addition of a short RNA primer
• DNA polymerase Enzyme – Addition of the new nucleotides
• Exonucleases Enzyme FEN1 Enzyme  and RNase H Enzyme – Removal of the RNA nucleotides formed initially.
• Enzyme Ligase– Combine the 2 separate DNA strands to one making it double stranded DNA.

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Purine are heterocyclic aromatic chemical compounds that are made up of Carbon atom, Hydrogen atom and Nitrogen atom.

The following are the purine examples that we will discuss in this article.

• Adenine
• Guanine
• Hypoxanthine
• Xanthine
• Theophylline
• Theobromine
• Caffeine
• Uric Acid
• Iso-guanine 

and many more.

In the nucleic acids both DeOxyRibose Nucleic acid which is known as the DNA and Ribonucleic Acid which is known as RNA, Adenine and guanine are the purine compounds present.

Read More on Sequence Of Nitrogenous Bases In DNA: What, Why, Purpose, Detailed Facts

Explanation on Structure of Purine and purine examples:

• Purines are aromatic heterocyclic compounds.
• The base chemical Code of purines is C5H4N4.
• It is a 2 -ring structure made up of a pyrimidine ring and an imidazole ring connected together.
• The pyrimidine ring in purine is a six membered ring and has 2 atoms of nitrogen in the 3, 1 region of the ring.
• The Imidazole ring in purine is a five membered ring and has 2 atoms of nitrogen in the seventh and ninth region of the ring.
• So totally the purine has four nitrogen atoms in it that are in the first, third, seventh and ninth place or position.

Read more on Biosynthesis of Purines and Pyrimidines | An important part of cellular metabolism

Detailed Characteristics of Adenine:

• Adenine is one of the five nitrogenous bases (Adenine, cytosine, guanine, uracil, thymine) present in the nucleic acids (DNA, RNA).
• A subunit of Adenine which is called the adenosine triphosphate also called ATP is the energy molecule that is utilized by the cell for biochemical reactions.
• The chemical Code is C5H5N5
• Adenine-purine pairs with thymine which is a pyrimidine.
• The IUPAC Name of Adenine is 9H-purin-6-amine.
• The Molar mass of adenine is 135.13 g/mol and Density of adenine is 1.6 g/ cm3

Read More on Adenine vs Thymine: Comparative Analysis

Characteristics of Guanine:

• Guanine is similar to adenine.
• The chemical code of guanine is C5H5N5O.
• The IUPAC Name of Guanine is 2-amino-1H-purin-6(9H)-one.
• A portion of guanine which is called as Guanosine triphosphate which is an energy molecule and also aids in the cell signaling mechanisms.
• The structure is very similar to adenine with few differences.
• The difference between adenine and guanine is that the presence of amine group in adenine on C6, and an extra double bond between C6 and N1 in its complementary pyrimidine ring whereas the amine group in guanine is on C2 and a carbonyl group on C6 in its pyrimidine ring.

Read more on Is Guanine A Purine :Why And Detailed facts

Characteristics of Hypoxanthine:

• Hypoxanthine is a purine organic compound that is majorly found in muscle tissues of humans.
• Hypoxanthine has OXO substituent at the 6th position.
• Hypoxanthine is a fundamental metabolite.
• The IUPAC name of Hypoxanthine is 1,9-Dihydro-6H-purin-6-one.
• Hypoxanthine is the product of purine catabolism.
• Rarely they are present in nucleic acids and aid in the salvage pathway for nucleic acid synthesis.
• Hypoxanthine is a PARP-poly(ADP-ribose) polymerase (PARP)Inhibitor which has anti-inflammatory and cyto-protective effects.

Characteristics of Xanthine:

• Xanthine is an oxopurine in which the second and sixth positions have an oxo group. 
• It is present in the bodily fluids and tissues even in urinary calculi.
• Degradation of adenosine mono-phosphate is performed by xanthine as an intermediate to form uric acid.

Characteristics of Theophylline:

• The chemical name of Theophylline is 1,3-dimethylxanthine
• It is used to relax the smooth muscles.
• The chemical code for theophylline is C7H8N4O2.
• It is also called Elixophyllin.

Characteristics of Theobromine

• Theobromine which is also called dimethylxanthine by having 2 methyl groups in the third and seventh position.
• It is a purine derivative that is obtained from the cacao plant commonly known as chocolate.
• It is an adenosine receptor antagonist and also a metabolite. 

Characteristics of Caffeine:

• A Xanthine alkaloid that is found in the seeds and other plant parts of certain plants.
• The chemical code of Caffeine is C8H10N4O2.
• It is also a natural pesticide.
• High doses of this compound may lead to enzyme elevation and damage the liver.

Read More on Adenine structure in RNA: Detailed Facts

Characteristics of Uric Acid:

• The chemical code of uric acid is C5H4N4O3.
• Uric acid is a product of protein metabolism that is found in bodily fluids like urine, blood etc..
• Uric acid is also called 2,6,8-hydroxypurine.
• The IUPAC Name of Uric acid is 7,9-dihydro-3H-purine-2,6,8-trione.

Read More on Purine metabolism | Importance in human physiology

Characteristics of Isoguanine:

• Isoguanine is an oxopurine as the amino group is positioned at the 6th place.
• Iso guanine is also called 6-amino-7H-purin-2-ol, 6-amino-3,7-dihydro-2H-purin-2-one.
• The chemical code of Isoguanine is C5H5N5O.
• The IUPAC name of isoguanine is 6-amino-1,7-dihydropyran-2-one.

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RNA is a single strand molecule that is closely related to DNA. RNA strands have 4 nitrogenous bases which are guanine, adenine, uracil and cytosine. So how is RNA Antiparallel and what does it mean being in antiparallel orientation.

Is RNA Antiparallel, Yes. RNA strand being a single strand it is antiparallel in nature. RNA strands have 4 nitrogenous bases which are Guanine, Adenine, Uracil (in case of DNA, it is Thymine) and Cytosine. This article is completely highlighted on how the  single stranded RNA is antiparallel in nature.

Now before getting into the topic- Is RNA antiparallel, we need to understand the basic structure of how the nitrogenous bases are combined or paired up so that understanding the concept of antiparallel RNA will be easy.

Basically in RNA there are 2 components that are purine and pyrimidine.

Adenine and Guanine are considered to be Purine whereas Uracil and Cytosine are considered to be pyrimidine.

So one Purine pair with one pyrimidine.

Adenine pairs up with uracil and cytosine pair up with guanine.

What is antiparallel RNA?

To make this simple, parallel is when 2 lines are placed nearby and they do not intersect.

Antiparallel RNA strand is when the RNA strand is complementary to another strand and runs in the opposite direction: that is one strand runs from 5’ prime end to 3’ prime end and the other strand from 3’ prime end to 5’ prime end.

This can be in case of one genomic DNA and one synthesized RNA Strand or the other case is there can be structures in which the one single RNA strand folds itself and pairs into the same strand.

The synthesized RNA strand is antiparallel and complementary to the other strand.

Why does RNA have antiparallel strands?

RNA have antiparallel strands

If the RNA strands are parallel to the template strand the bonding of hydrogen is not possible. 

We have already discussed that Adenine and Cytosine pairs with Uracil and Guanine respectively in RNA. This is possible only when the hydrogen bond is present. So in order to have them intact with all the nitrogenous pairs, sugars and phosphate they must run antiparallel.

Read More on Do Prokaryotes Have RNA: Why, How And Detailed Insights

Is RNA parallel?

No, in general be it DNA OR RNA they do not possess parallel orientation.

But in few cases, the DNA or RNA can fold into alternative structures and show up in parallel orientation which is rare and can not be taken into great consideration in science.

Read More on DNA Structure | A detailed insight with all crucial aspects

Frequently Asked Questions on Is RNA Antiparallel.

Why is RNA considered antiparallel strands?

We know that the sugar molecule and the phosphate is like the backbone of a RNA structure.

This is because of the pairing of nitrogenous bases. The Adenine and uracil pair up and the cytosine and guanine pair. So during this process the rna strand has to run through antiparallel orientation.

This is why RNA is considered an antiparallel strand.

Read More on DNA Supercoiling | A Vital Mechanism for DNA Packaging

Explanation on Structure of antiparallel RNA Strand

• RNA is usually a single stranded component and it is made of specific nucleotides called the ribonucleotides that are held together by the phosphodiester bond.
• The ribonucleotides is composed of the sugar molecule that is specific for RNA known as ribose, it is a pentose sugar molecule, a nitrogenous base- any one from the four bases- Purine and pyrimidine (Adenine, uracil, guanine, cytosine) and the major backbone of this structure the phosphate group.
• The ultimate morphological difference between the sugars-deoxyribose in case of DNA, Ribose in case of RNA.
• The uracil is a pyrimidine compound that is observed only in RNA that pairs with adenine. (In the case of DNA, uracil is replaced by Thymine).
• Being a single stranded structure, RNA can show up intra intra-connective molecular structure by pairing of the bases among the same strand that is complementary and thus being antiparallel.
• This intra-connective molecular structure produces a clear three dimensional structure that does the required or targeted function.

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Cilia are very minute structures that resemble a strand of hair that is present in the eukaryotic organisms. Their functions vary based on the location or cell they are present.

Do Animal Cells Have Cilia, Yes. Animal cells have cilia in them. Just like flagella, cilia is also present in animal cells. In multi-celled organisms, the function of cilia is to transport the cell or bodily fluids or any components in the system. In mammals, cilia is found in the respiratory tract (upper) for the protection of lungs.

Do all animal cells have cilia?

The function of cilia is based on the location they are present or it may vary by many factors.

Cilia is present in most of the animal cells but not in all animal cells.

Read more on Are Protists Eukaryotic.

What are the different types of cilia?

Cilia are of 2 types

• Motile cilia
• Non motile cilia

Motile cilia:

This type of cilia are present on the surface of the respiratory tract.

Non- motile cilia:

This type of  cilia are called the primitive type of cilia that aid in the sensory signaling pathway like proper kidney functioning 

Where is cilia in an animal cell?

Cilia can be motile cilia and non-motile cilia.

Cilia are usually found on the surface of the cell- all over and in numerous numbers. They are found in the epithelium layer in the respiratory tract which is called the respiratory epithelium in humans.

In humans, the cilia present in the epithelium (respiratory tract) aids in the clearance of mucus and other secretory components in the respiratory tract.

Read More on Do animal cells have vacuoles.

Explanation on structure of cilia:

Cilia are minute thread like structures.

Each minute thread is made up of Microtubules. Each contains 9 Microtubules in pairs as the outer ring and two polar microtubules in the center which is called as axonema.

The outer ring is made up of a protein (motor) called dynein.

Do all cells have cilia?

The cilia will be present in only certain cells which are supposed to have its function. So the answer is 

No, Cilia is not present in all cells.

Do plant cells have cilia?

Plant cells are eukaryotic cells, so do they have cilia in them?

No, In general plant cells do not have cilia in them.

So all plant cells do not have cilia?- No.

Which plant cell has cilia?

All plant cells do not have cilia except one.

The cycad sperm cell contains cilia in it just like other sperm cells. Since this is the only plant cell that is ciliated, in general it is mentioned that plant cells do not have cilia but the cycad sperm cell do have a cilia in them.

Read more on Do humans have plant cell.

What is the Role of Channel Proteins in Active Transport in Animal Cells with Cilia?

Channel proteins play a crucial role in active transport within animal cells with cilia. These specialized proteins act as gateways, allowing specific molecules to enter or exit the cell. Through active transport, channel proteins use energy to move molecules against their concentration gradient, ensuring essential substances are transported to where they are needed. Cilia, with their hair-like structures, aid in the movement of the cell and enhance the efficiency of channel protein active transport.

Why don’t plant cells have cilia?

The intent of the organelle cilia and flagella is for motility.

Plant cells do not require moving. In addition, in animal cell these components aid in organizing the microtubules. In plant cell, they possess a very strong cell wall that keeps the microtubules intact during cell division thus not requiring cilia.

Function of cilia:

• The main function of cilia is that they aid in locomotion and also in the sensory function.
• They have a significant role in cell cycle, cell replication in animals and in humans.
• Cilia collectively move in a rhythmic motion that aid in the clearance of dirt and excess mucus or any antigenic molecule at that specific region.
• Non- motile cilia have a antenna like structure that aid in sensory function. They obtain information from the cells and signals the target.
• Example: Cilia in kidney cells aid in urine flow, the Cilia in the retina- photoreceptor aid in the flow of molecules from one terminal to another.

Also Read:

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