DNA repair mechanisms

This lecture explains about the DNA repair mechanisms in cell.
Download the study materials here-
Cells cannot function if DNA damage corrupts the integrity and accessibility of essential information in the genome (but cells remain superficially functional when so-called "non-essential" genes are missing or damaged). Depending on the type of damage inflicted on the DNA's double helical structure, a variety of repair strategies have evolved to restore lost information. If possible, cells use the unmodified complementary strand of the DNA or the sister chromatid as a template to recover the original information. Without access to a template, cells use an error-prone recovery mechanism known as translesion synthesis as a last resort.

Damage to DNA alters the spatial configuration of the helix, and such alterations can be detected by the cell. Once damage is localized, specific DNA repair molecules bind at or near the site of damage, inducing other molecules to bind and form a complex that enables the actual repair to take place.
Direct reversal

Cells are known to eliminate three types of damage to their DNA by chemically reversing it. These mechanisms do not require a template, since the types of damage they counteract can occur in only one of the four bases. Such direct reversal mechanisms are specific to the type of damage incurred and do not involve breakage of the phosphodiester backbone. The formation of pyrimidine dimers upon irradiation with UV light results in an abnormal covalent bond between adjacent pyrimidine bases. The photoreactivation process directly reverses this damage by the action of the enzyme photolyase, whose activation is obligately dependent on energy absorbed from blue/UV light (300--500 nm wavelength) to promote catalysis.[16] Another type of damage, methylation of guanine bases, is directly reversed by the protein methyl guanine methyl transferase (MGMT), the bacterial equivalent of which is called ogt. This is an expensive process because each MGMT molecule can be used only once; that is, the reaction is stoichiometric rather than catalytic.[17] A generalized response to methylating agents in bacteria is known as the adaptive response and confers a level of resistance to alkylating agents upon sustained exposure by upregulation of alkylation repair enzymes.[18] The third type of DNA damage reversed by cells is certain methylation of the bases cytosine and adenine. Source of the article published in description is Wikipedia. I am sharing their material. © by original content developers of Wikipedia.

[quotesandcaptions]

We want you to be in front of camera 🥺
And plz write in board 🙏🏻 so that we can understand more clearly .... your old videos where you simultaneously drew and explained the topics are much much more helpful and comfortable for us 💕 from WB

[jiveshgarg.]

Sir, its too good.
But actually i came here for studying direct repair only, and found that sound wasnt on sync, it had audio of other mechanism and video of direct repair.... :(

[msso]

I was really trying to follow this, but you lost me at the end. The video was not going with the audio. You should correct this.

[ritikabhardwaj]

Thanks so much best video on YouTube for this topic 🙏🙏🙏🙏

[jadirafransiscanortonrosef]

DNA Repair is An outmust in my researcher today/very delighted in this brainstorm where outstanding not let continuance of medical capacity///

[aninditaghosh]

sir ami medical college e pori ...
aapnar vedio gulo darun laage...
happy teacher's day

[sadiqaisha]

Thank you so much for your videos, they are so helpful by Allah!

[jag]

thank you for the explanation but from 29' until the end is wrong synchronized,

[Rickandmorty_com]

sound goes off sync by like a minute starting around 28:00

[goldadcosta]

Hi.. in DNA repair from where has uracil come to pair normally with adenine?

[banditapujari]

From 30:04 the audio and video doesn't match anymore. 😫

[nishapaudel]

Make one video but make it, the best rather than hundreds of videos with poor quality ....best your future...

[Wordboost]

Sir make a video on how to prepare for msc zoolgy e entrance exam for DU and AMU.. Plz...

[JamesCarmichael]

Great video if a bit out of my league :) I was born with Achromatopsia where a gene has been deleted/mutated and I've been looking for natural ways of correcting this. The condition effects my cone cells in my retina and tus my vision is very poor and I'm extremely sensitive to light. I've heard Meditation, Sungazing, Raw Food Diet and a few other things can help the body to naturally repair DNA. Whats you take on that? Thanks by the way.

[remieres]

Question I'm only a Highschool grad who failed biology, but I take interest at times. My question is. Is a mutation in the DNA code in a blood cell deadly to the organism? and how many accumulated mutations would be enough to kill a human infant in the genome? so say we have 40Million codes CGTA so if one sentence is damaged or otherwise mutated negative or positive. When would that kill the fetus, the baby, or the adult? Because I hear many say that it is lethal to the cell, but to what scale does it become lethal to the organism?

[axa.n]

during explanation of mismatch repair, captions were of direct reversal repair 😑

[profasadkhan]

Presentation is poor as well as some places wrong terminology was used which may mislead students, eg DNA Polymerase cant seal at Base Excision Repair site rather ligase . it must be corrected.

[sarahibrahimhashoosh]

what is the application to record this video

[euphoricsaga]

Hi 👋 sir you are wonderful ji wonderful

[mansisiddhpara]

Content is ohk but clearing is very poor!