6085713
Description
Flashcards by Emma Allde, updated more than 1 year ago
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Created by Emma Allde
over 7 years ago
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| 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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