What is DNA damage and repair?
DNA Damage and Repair Mechanisms Changes to the cellular genome can generate errors in the transcription of DNA and ensuing translation into proteins necessary for signaling and cellular function.
What is the role of recombination in repairing damaged DNA?
Recombination repair is a mechanism for generating a functional DNA molecule from two damaged molecules. It is an essential repair process for dividing cells because a replication fork may arrive at a damaged site, such as a thymine dimer, before the excision repair system has eliminated damage.
What do you mean by DNA damage?
DNA damage is defined as an alteration in DNA structure that is capable of causing cellular injury and reduces viability or reproductive fitness of the organism (Kaufmann and Paules, 1996).
What is a repair gene?
DNA repair gene, Med1: A gene that codes for one of the key enzymes involved in repairing DNA. The DNA in genes is constantly mutating and being repaired. This repair process is controlled by special genes.
What causes DNA damage?
DNA can be damaged via environmental factors as well. Environmental agents such as UV light, ionizing radiation, and genotoxic chemicals. Replication forks can be stalled due to damaged DNA and double strand breaks are also a form of DNA damage.
What are DNA repair mechanisms?
There are three types of repair mechanisms: direct reversal of the damage, excision repair, and postreplication repair. Direct reversal repair is specific to the damage. For example, in a process called photoreactivation, pyrimidine bases fused by UV light are separated by DNA photolyase (a light-driven enzyme).
What are the types of DNA repair?
At least five major DNA repair pathways—base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage.
What are types of DNA damage?
DNA damage can be subdivided into two types: (1) endogenous damage caused by reactive oxygen species (ROS) that are derived from metabolic byproducts and (2) exogenous damage caused by radiation (UV, X-ray, gamma), hydrolysis, plant toxins, and viruses.
What are DNA repair genes called?
| Gene Name (synonyms) linked to GeneCards Some gene products act in more than one pathway, but each is listed only once below | Activity linked to OMIM |
|---|---|
| HFM1 | Helicase in meiotic-crossover formation |
| Nucleotide excision repair (NER) | (XP = xeroderma pigmentosum) |
| XPC | Binds DNA distortions XPC, RAD23B, CETN2 |
| RAD23B |
How can DNA damage create a mutation?
DNA can be damaged by radiation and reactive molecules, such as free radicals. As discussed in the animation, this damage may create mutations by chemically changing the DNA. Most mutations are corrected by DNA repair processes in the cell.
Why is DNA recombination important?
Beyond its role in meiosis, recombination is important to somatic cells in eukaryotes because it can be used to help repair broken DNA, even when the break involves both strands of the double helix. These breaks are known as double-stranded breaks, or DSBs.
What is DNA recombination and repair?
DNA Recombination and Repair. In cases where DNA is severely damaged, a cell will engage in a phenomenon called the SOS response in an effort to salvage a functioning set of genetic information. This response, also called error‐prone repair, represents a last‐ditch response to salvage a chromosomal information system.
What are the four mechanisms of DNA repair?
The cell possesses an inbuilt system to repair the damaged DNA. This may be achieved by four distinct mechanisms (Table 3.2). 1. Base excision-repair 2. Nucleotide excision-repair 3. Mismatch repair 4. Double-strand break repair. 1. Base excision-repair:
How is DNA damaged and repaired by endonuclease?
An endonuclease cuts the backbone of DNA strand near the defect and removes a few bases. The gap so created is filled up by the action of repair DNA polymerase and DNA ligase. 2. Nucleotide excision-repair:
What happens if DNA is damaged during replication?
As already stated, damage to DNA caused by replication errors or mutations may have serious consequences. The cell possesses an inbuilt system to repair the damaged DNA. This may be achieved by four distinct mechanisms (Table 3.2).
