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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 .
DNA condensation refers to the process of compacting DNA molecules in vitro or in vivo. [1] Mechanistic details of DNA packing are essential for its functioning in the process of gene regulation in living systems. Condensed DNA often has surprising properties, which one would not predict from classical concepts of dilute solutions.
The organization of DNA presents a remarkable biological challenge: human DNA can reach 2 meters [1] and is packed into the nucleus with the diameter of 5-20 µm. [2] At the same time, the critical cell processes involve complex processes on highly compacted DNA, such as transcription, replication, recombination, DNA repair, and cell division.
Light-dependent reactions of photosynthesis at the thylakoid membrane. Photosystems are functional and structural units of protein complexes involved in photosynthesis. Together they carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons.
Since then, hundreds of chloroplast genomes from various species have been sequenced, but they are mostly those of land plants and green algae—glaucophytes, red algae, and other algal groups are extremely underrepresented, potentially introducing some bias in views of "typical" chloroplast DNA structure and content.
All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. [15] The basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar (ribose or deoxyribose), a phosphate group, and a nucleobase. [16]
In most organisms, DNA polymerases function in a large complex called the replisome that contains multiple accessory subunits, such as the DNA clamp or helicases. [135] RNA-dependent DNA polymerases are a specialized class of polymerases that copy the sequence of an RNA strand into DNA.
[21] [22] Both RNAi and an exosome-dependent RNA degradation process contribute to heterochromatic gene silencing. These mechanisms of Schizosaccharomyces pombe may occur in other eukaryotes. [23] A large RNA structure called RevCen has also been implicated in the production of siRNAs to mediate heterochromatin formation in some fission yeast. [24]