Th2L02 DNA repair mechanisms


Medicine Y1 (Theme 2 | Genetics) Flashcards on Th2L02 DNA repair mechanisms, created by Emma Allde on 21/08/2016.
Emma Allde
Flashcards by Emma Allde, updated more than 1 year ago
Emma Allde
Created by Emma Allde over 7 years ago

Resource summary

Question Answer
What is the role nuclease Removes the wrong nucleotide added by polymerase
Which direction does (exo)nuclease work 3-5'
What enzyme adds the correct nucleotides back to the DNA DNA polymerase with ATP
What does exonuclease prevent the accumulation of mutations
What is the overall, final error rate of eukaryotic DNA after exonuclease activity 1 in 10^10 or 1 in every 100 billion bases
Mutated genes result in what abnormal proteins
What are two pathogenic things than can happen as a result of abnormal proteins important loss of function OR gain in toxic function
What are most cancer cells in mammals caused by point mutations in proteins that control cell growth
What is the end replication paradox The ends of linear chromosomes are lost after each round of replication, and once the RNA primers have been removed, the lagging strand is shorter than the leading strand at the 5' end
What are teleomeres A long region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration or from fusion with neighbouring chromosomes
What addresses the end replication paradox teleomeres
What is teleomerase an enzyme that catalyses the lengthening of telomeres
What is teleomerase accompanied by a short-strand of RNA that serves as a template for new telomere segments (as opposed to using a chromosomal template)
What is the relationship b/w somatic cells and telomerease Telomerase is turned off so with every division the telomeres get shorter
What is the Telomerase catalytic protein component (2) Activates telomerase activity Extends the length of telomerase and extends the lifespan by more than 5 times
What does the telomerase catalytic protein component suggest that your lifespan is limited by telomere length rather than vice versa
What is Senescence The natural physical decline brought about by aging
What cells human maintain telomerase activity into adulthood, necessary for carrying complete genes on to our progeny Gametes
What is the Hayflick limit • The number of times a human cell is capable of dividing into two new cells • The limit for most human cells is approximately 50 divisions, an indication that the life span is limited by our genetic programme
What is the role of the RNA template It combines with DNA overhang, serving as an anchor site for to telomerase interacts with DNA It directs sequential nucleotide addition, extending the 3' end of the chromosomal DNA
What is the RNA template A template, short than a telomere but with a shift than allows for the RNA template to shift forwards and begin copying the template again
What is direct repair DNA repair in which modified bases are changed back into their original structure via removal of damaged region followed by re-synthesis
What are the forms of direct DNA repair R
What is nucleotide excision repair (NER) Distorted helix results in region around damage removed by nuclease and helicase action > re-synthesis
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