Search results
Results from the WOW.Com Content Network
A circular chromosome is a chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromosome of most eukaryotes. Most prokaryote chromosomes contain a circular DNA molecule. This has the major advantage of having no free ends to the DNA.
D-loop replication is a proposed process by which circular DNA like chloroplasts and mitochondria replicate their genetic material. An important component of understanding D-loop replication is that many chloroplasts and mitochondria have a single circular chromosome like bacteria instead of the linear chromosomes found in eukaryotes.
The 154 kb chloroplast DNA map of a model flowering plant (Arabidopsis thaliana: Brassicaceae) showing genes and inverted repeats. Chloroplast DNAs are circular, and are typically 120,000–170,000 base pairs long. [7] [8] [9] They can have a contour length of around 30–60 micrometers, and have a mass of about 80–130 million daltons. [10]
Circular DNA is DNA that forms a closed loop and has no ends. Examples include: Plasmids, mobile genetic elements; cccDNA, formed by some viruses inside cell nuclei; Circular bacterial chromosomes; Mitochondrial DNA (mtDNA) Chloroplast DNA (cpDNA), and that of other plastids; Extrachromosomal circular DNA (eccDNA)
Extrachromosomal circular DNA (eccDNA) is a type of double-stranded circular DNA structure that was first discovered in 1964 by Alix Bassel and Yasuo Hotta. [1] In contrast to previously identified circular DNA structures (e.g., bacterial plasmids, mitochondrial DNA, circular bacterial chromosomes, or chloroplast DNA), eccDNA are circular DNA found in the eukaryotic nuclei of plant and animal ...
Circular plasmids have been isolated and found in many different plants, with those in Vicia faba and Chenopodium album being the most studied and whose mechanism of replication is known. The circular plasmids can replicate using the θ model of replication (as in Vicia faba) and through rolling circle replication (as in C.album). [60]
It is often found in the chloroplasts of C 4 plants, though it has also been found in some C 3 angiosperms, [23] and even some gymnosperms. [125] The chloroplast peripheral reticulum consists of a maze of membranous tubes and vesicles continuous with the inner chloroplast membrane that extends into the internal stromal fluid of the chloroplast.
This process occurs in bacteria, whose single circular DNA is cut by DNA gyrase and the two ends are then twisted around each other to form supercoils. Gyrase is also found in eukaryotic plastids : it has been found in the apicoplast of the malarial parasite Plasmodium falciparum [ 5 ] [ 6 ] and in chloroplasts of several plants. [ 7 ]