What is homologous recombination DNA repair?
Definition. Homologous recombination repair is a DNA repair process that includes the invasion of an undamaged DNA molecule by a damaged molecule of identical or very similar sequence. Resynthesis of the damaged region is accomplished using the undamaged molecule as a template.
What is direct reversal of DNA damage?
Direct reversal of DNA damage is a mechanism of repair that does not require a template and is applied to two main types of damage. UV light induces the formation of pyrimidine dimers which can distort the DNA chain structure, blocking transcription beyond the area of damage.
What is direct repair of DNA?
Introduction. Direct repair is defined as the elimination of DNA and RNA damage using chemical reversion that does not require a nucleotide template, breakage of the phosphodiester backbone or DNA synthesis.
What is homologous DNA sequences?
A homologous gene (or homolog) is a gene inherited in two species by a common ancestor. While homologous genes can be similar in sequence, similar sequences are not necessarily homologous. Orthologous are homologous genes where a gene diverges after a speciation event, but the gene and its main function are conserved.
Which types of DNA damages are reversible?
Mechanisms
- Direct reversal. Cells are known to eliminate three types of damage to their DNA by chemically reversing it.
- Single-strand damage. Structure of the base-excision repair enzyme uracil-DNA glycosylase excising a hydrolytically-produced uracil residue from DNA.
- Double-strand breaks.
- Translesion synthesis.
What are the three steps in DNA repair?
There are three types of repair mechanisms: direct reversal of the damage, excision repair, and postreplication repair.
What are the 2 types of DNA?
There are two types of DNA in the cell – autosomal DNA and mitochondrial DNA. Autosomal DNA (also called nuclear DNA) is packaged into 22 paired chromosomes. In each pair of autosomes, one was inherited from the mother and one was inherited from the father.