Quick Answer: Which Type Of DNA Damaging Agent Is Most Likely To Cause Double Strand Breaks?

What is the primary mechanism used to repair double stranded DNA breaks?

Cells employ two primary mechanisms, homologous recombination (HR) and non-homologous end-joining (NHEJ) to deal with double strand breaks [14-22].

During HR, an intact, homologous DNA duplex is used as a template for double strand break (dsbr) repair [14-17]..

What is the most common repair mechanism for double strand breaks?

homologous recombinationDouble-strand DNA breaks are common events in eukaryotic cells, and there are two major pathways for repairing them: homologous recombination and nonhomologous DNA end joining (NHEJ). The diverse causes of DSBs result in a diverse chemistry of DNA ends that must be repaired.

What is a double stranded DNA break?

Definition. A double-strand DNA break (DSB) occurs or arises when both strands of the DNA duplex are severed, often as the result of ionizing radiation.

How do you induce a double strand break?

DNA double-strand breaks (DSBs) are one of many types of DNA damage that occur spontaneously in all living organisms. DSBs can be induced by ionizing radiation, radiomimetic chemicals or reactive oxygen species, but also during DNA replication when a polymerase encounters a single-strand lesion at a replication fork1.

How do you fix a double strand break?

DNA double-strand breaks are repaired by means of two main mechanisms: nonhomologous end joining and homologous recombination (see Figure 1). Both mechanisms operate in all eukaryotic cells that have been examined but the relative contribution of each mechanism varies.

Why do the grooves of B DNA have different sizes?

Note that the major groove displays more features that distinguish one base pair from another than does the minor groove. The larger size of the major groove in B-DNA makes it more accessible for interactions with proteins that recognize specific DNA sequences.

What causes single strand breaks in DNA?

Physical agents including ionizing radiation and UV light can lead to pyrimidine dimers. Radiation including medical treatments and diagnostics can lead to base damage, to single stranded and double stranded DNA breaks.

What happens in non homologous end joining?

Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. … When the overhangs are perfectly compatible, NHEJ usually repairs the break accurately. Imprecise repair leading to loss of nucleotides can also occur, but is much more common when the overhangs are not compatible.

What type of damaging agent causes double strand breaks in DNA?

By-products of the cell’s own metabolism such as reactive oxygen species can damage DNA bases and cause lesions that can block progression of replication. The result is double-strand breaks (DSBs) in the chromosome.

What kind of DNA break is more dangerous?

Double strand breaksDouble strand breaks are considered the most dangerous of all the DNA lesions. If left unrepaired, the resulting chromosome discontinuity often results in death. There are two main ways to repair a double strand break.

What foods help repair DNA?

In a study published in the British Journal of Cancer (published by the research journal Nature) the researchers show that in laboratory tests, a compound called indole-3-carinol (I3C), found in broccoli, cauliflower and cabbage, and a chemical called genistein, found in soy beans, can increase the levels of BRCA1 and …

What is one type of mutagen that can cause DSBs?

Clastogens can induce DSBs indirectly, via the above-described cellular processes. Chemical agents that induce strand breaks directly are commonly referred to as “radiomimetic” compounds because of their ability to induces DSBs.

Which enzyme is activated during double stranded break?

SUMMARY The RecBCD enzyme of Escherichia coli is a helicase-nuclease that initiates the repair of double-stranded DNA breaks by homologous recombination. It also degrades linear double-stranded DNA, protecting the bacteria from phages and extraneous chromosomal DNA.

Why is DNA double stranded?

DNA is double-stranded because it helps it better perform its job. To elaborate, DNA is the basic hereditary information of a cell. … The two strands of DNA are held together via hydrogen bonds, which allow the sequence to be “unzipped” for replication or transcription.

How are DNA breaks repair in prokaryotes?

First the damage is recognized, then 12-24 nucleotide-long strands of DNA are removed both upstream and downstream of the damage site by endonucleases, and the removed DNA region is then resynthesized. NER is a highly evolutionarily conserved repair mechanism and is used in nearly all eukaryotic and prokaryotic cells.