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Mitochondrial DNA is a small portion of the DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus, and, in plants and algae, the DNA also is found in plastids, such as chloroplasts. [3] Human mitochondrial DNA was the first significant part of the human genome to be sequenced. [4]
Chloroplast DNA (cpDNA), also known as plastid DNA (ptDNA) is the DNA located in chloroplasts, which are photosynthetic organelles located within the cells of some eukaryotic organisms. Chloroplasts, like other types of plastid , contain a genome separate from that in the cell nucleus .
The genes located in mitochondria and chloroplasts are very important for proper cellular function. The mitochondrial DNA and other extranuclear types of DNA replicate independently of the DNA located in the nucleus, which is typically arranged in chromosomes that only replicate one time preceding cellular division. The extranuclear genomes of ...
In addition to the chromosomes in the nucleus, organelles such as the chloroplasts and mitochondria have their own DNA. Mitochondria are sometimes said to have their own genome often referred to as the "mitochondrial genome". The DNA found within the chloroplast may be referred to as the "plastome". Like the bacteria they originated from ...
Mitochondrial diseases range in severity from asymptomatic to fatal, and are most commonly due to inherited rather than acquired mutations of mitochondrial DNA. A given mitochondrial mutation can cause various diseases depending on the severity of the problem in the mitochondria and the tissue the affected mitochondria are in.
In general, mitochondrial DNA lacks introns, as is the case in the human mitochondrial genome; [144] however, introns have been observed in some eukaryotic mitochondrial DNA, [146] such as that of yeast [147] and protists, [148] including Dictyostelium discoideum. [149] Between protein-coding regions, tRNAs are present.
Mitochondria and plastids contain their own ribosomes; these are more similar to those of bacteria (70S) than those of eukaryotes. [74] Proteins created by mitochondria and chloroplasts use N-formylmethionine as the initiating amino acid, as do proteins created by bacteria but not proteins created by eukaryotic nuclear genes or archaea. [75] [76]
Unlike nuclear DNA, which is present as linear molecules inside the chromosomes, the entire genomes of chloroplasts and mitochondria are present on a single molecule of double-stranded circular DNA molecule; this is very similar structure to a bacterial chromosome.