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The expression of genes encoded in DNA begins by transcribing the gene into RNA, a second type of nucleic acid that is very similar to DNA, but whose monomers contain the sugar ribose rather than deoxyribose. RNA also contains the base uracil in place of thymine. RNA molecules are less stable than DNA and are typically single-stranded.
The transferred DNA (called T-DNA) is piloted to the plant cell nucleus by nuclear localization signals present in the Agrobacterium protein VirD2, which is covalently attached to the end of the T-DNA at the Right border (RB). Exactly how the T-DNA is integrated into the host plant genomic DNA is an active area of plant biology research.
The gene expression patterns that define cell identity are inherited through cell division. [1] This process is called epigenetic regulation. DNA methylation is reliably inherited through the action of maintenance methylases that modify the nascent DNA strand generated by replication. [1] In mammalian cells, DNA methylation is the primary ...
Genes are copied each time a cell divides into two new cells. The process that copies DNA is called DNA replication . [ 8 ] It is through a similar process that a child inherits genes from its parents when a copy from the mother is mixed with a copy from the father.
The last stage of the cell division process is cytokinesis. In this stage there is a cytoplasmic division that occurs at the end of either mitosis or meiosis. At this stage there is a resulting irreversible separation leading to two daughter cells. Cell division plays an important role in determining the fate of the cell.
DNA damages arise in each cell, every day, with the number of damages in each cell reaching tens to hundreds of thousands, and such DNA damages can impede primary transcription. [8] The process of gene expression itself is a source of endogenous DNA damages resulting from the susceptibility of single-stranded DNA to damage. [ 8 ]
Although the mitochondrial DNA is very small compared to nuclear chromosomes, [2] it codes for 13 proteins involved in mitochondrial energy production and specific tRNAs. Foreign genetic material (most commonly DNA) can also be artificially introduced into the cell by a process called transfection.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.