Do Chloroplasts Have DNA? 9 Facts You Should Know

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This article illustrates all around Information on “do chloroplasts have DNA?” with 9 facts in detail

The DNA of chloroplast also known as plastid DNA acts as an abundant semi-autonomous component of the plant that contain a helical, circular double standard DNA molecule.

Now take a look this 9 facts in a brief

Why do chloroplasts have DNA?

The DNA of chloroplast come from endosymbionts, which evolved from cyanobacteria also known as endosymbiotic cyanobacteria.

The DNA of chloroplast also known as plastid DNA acts as an abundant semi-autonomous component of the plant. It possesses its genetic systems with its genome. It is a double-helical, circular double standard DNA molecule.Chloroplast is one kind of bioenergetics subcellular organelles that have a double membrane and it is one kind of biconcave disc around 3 to 10 micrometers in diameter that consisting of thylakoid, which acts as a compartment containing flattened fluid-filled sacs.

The arrangement of the thylakoid is look like a stack is known as a granum (one thylakoid stack) or grana (plural form of granum) Integral lamina joins grana to each other.The DNA of chloroplast also known as plastid DNA acts as an abundant semi-autonomous component of the plant. It possesses its genetic systems with its genome. It is a double-helical, circular double standard DNA molecule.

The cytosolic part contains a nuclear chromosomal gene that encodes some precursor proteins and cytosolic proteins. After such gene import into the organelles in which it evolved as an endosymbiont. Simply aerobic prokaryotes are engulfed by the cell of eukaryotes that form an endosymbiotic relationship or make an association with the eukaryotic host to form their DNA.

800px Chloroplast endosymbiosis.svg
do chloroplasts have DNA example
Image from Wikimedia.org

Where do chloroplasts have DNA?

The Chloroplast has a double-membrane structure with single DNA molecules which present in multiple copies. The DNA of the chloroplast is enclosed within the stroma is one fluid-filled internal space of chloroplast, and attached to the chloroplast membrane.

It also has some other nuclear components including RNAs and ribosomes, starch granules, and some dissolved enzymes that are required for photosynthesis in a light-independent manner also known as a Calvin cycle.

Do chloroplasts have circular DNA?

Yes, Chloroplast has circular double-stranded DNA that varies in size from 120,000 to 247,000 nucleotides long. The circular DNA of chloroplast is semi-autonomous genetically.

They also contain some inverted repeats, which have two genes of tRNA and three genes for ribosomal RNA. The inverted repeats of this chloroplast help to stabilize the whole genome of the chloroplast. There are several copies of nucleoids around 100 that can able to store identical chloroplast rings.

Chloroplasts DNA Structure

The DNA of chloroplast also known as plastid DNA acts as an abundant component of plant total DNA. It is a double-helical, circular double standard DNA molecule. In high plants, chloroplast can be around 120 to 160kb in size and 135,000bp in length.

The DNA of chloroplast is coded for certain structural proteins of the thylakoid membrane, Chloroplast mRNA, rRNA and tRNA, and chloroplast ribosomal proteins that are essential for the various functions of the chloroplast. For the light-dependent reaction and the process of photosynthesis, the chloroplast membrane contains different kinds of enzymes, photosynthetic pigments, a single circular chromosome termed DNA, and electron careers.

TThe genes present in chloroplast DNA that encode for chloroplast protein biosynthetic apparatus like structural components of chloroplast ribosomes subunits, RNA pol subunits, and set of tRNAs. The chloroplast DNA has the gene for a catalytically active subunit of enzyme RUBP Carboxylase, Polypeptide components of photosystem for capturing sunlight, thegene for rRNA, tRNAs, and ribosomal proteins, and contains units of chloroplast specific RNA polymerase.

The gene of this chloroplast DNA specifies the photosynthetic machinery like electron transport chain, PS, and PSI I. The photosynthetic pigments or one kind of chlorophyll molecule which is embedded in the thylakoid membrane and arranged in these two types of the photosystem, PSI and PSII, can absorb light and do the process of electron transport chain for the synthesis of ATP. The most important properties of chloroplasts are inherited independently of nuclear genes, Non-mendelian, inheritance of somatic segregation in plants and self-replication.

Chloroplasts DNA Function

  1. The DNA of chloroplast also known as plastid DNA encodes the gene for three electron transport proteins, nine photosystem II proteins, and three photosystems I proteins.
  2. The gene of chloroplast involves in the process of photosynthesis in plants and other activities as well
  3. For the light-dependent reaction and the process of photosynthesis, the gene of chloroplast can make different kinds of enzymes, and encode genes for photosynthetic pigments, and electron careers.
  4. The DNA of chloroplast is coded for certain structural proteins of the thylakoid membrane, Chloroplast mRNA, rRNA and tRNA, and chloroplast ribosomal proteins that are essential for the various functions of the chloroplast
  5. The inverted repeats of chloroplast DNA help to stabilize the whole genome of the chloroplast organelle
  6. They can inherit independently of nuclear genes, Non-mendelian inheritance of somatic segregation in plants, and self-replication.
  7. It incode total 37genes for tRNA molecules to carry translation process,4 genes for the subunit of RNA polymerase for performing transcription and total 6 genes for the enzyme ATP synthase.
  8. It also contain genes around 60 proteins for the construction of ribosomes for their chloroplast

Chloroplast DNA Replication

During the availability of light, DNA replication occurs independently during the timing of chloroplast division or cell cycle. It can also able to do their replication in darkness via heterotrophic culture. The chloroplast DNA starts its replication unidirectionally by utilizing one strategy known as a double displacement loop or also known as a D loop replication mechanism.

During the beginning of replication, multiple replication forks will start to open up and it allows the machinery to start the process of replication. The movement of this D loop adopts a one theta intermediary form also known as a cairns replication intermediate after that they complete their whole replication via one mechanism known as a rolling circle mechanism. The new daughter chloroplast DNA chromosome create during the separation of the chloroplast DNA structure.

440px CpDNA Replication
do chloroplasts have DNA example
Image from Wikipedia

Chloroplast DNA Inheritance

The inheritance in the chloroplast is generally known as a cytoplasmic inheritance or extra-nuclear gene or extra-nuclear gene.

In cytoplasmic inheritance, the transmission of the gene occurs outside the nucleus Cytoplasmic DNA has two types, mitochondrial DNA and chloroplast DNA. There are most common examples of cytoplasmic inheritance including inheritance in Oenothera, Inheritance in mirabilis Jalapa and Zebrina.

Can chloroplasts Replicate?

The organelles are mainly dependent on their host. The chloroplast does not reproduce but chloroplast can replicate their DNA during chloroplast proliferation.

The chloroplast possesses multiple copies of its gene copies of DNA molecule also known as a plastome. The chloroplast can replicate similarly to bacteria by the process named binary fission or by nuclear-encoded proteins.

Difference between ChDNA and MitDNA

The DNA of chloroplast present inside the plant cells is mainly responsible for the process of Photosynthesis while inside the eukaryotic cell has mtDNA that is mainly responsible to act as a powerhouse of the cell. The human MitDNA has around 37 genes that are code for polypeptide,rRNA, and tRNA and the MtDNA is around 16,569 base pairs long. The chloroplast DNA has around 200genes with 120,000 to 170,000basepairs.

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