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Flashcards in lecture 3 Deck (15):
1

define 'gene'

a region of DNA that can be expressed to produce a final functional product that is either a polypeptide or RNA molecule

2

what is meant by: copy number variation?

sections of the genome are repeated, the number of repeats in the genome varies between individuals

3

what type of trait does achondroplasia result from? what is the impact of this on a cellular level?

autosomal dominant trait
mutation in the fibroblast growth factor receptor 3 gene

4

what is an anonymous SNP?

a single nucleotide polymorphism which has no known effect on gene function

5

what is a synonymous coding SNP?

encodes the same amino acid as the original

6

where are CNVs found and what causes them?

repetitive sequences caused by replication slippage

7

what is the genetic basis for Huntington's disease?

triplet expansion of CAG caused by replication slippage

8

how many CAG repeats are found in the normal gene and huntington's diseased gene?

normal: 6-39
diseased: 35-121

9

what is the molecular basis for DNA fingerprinting?

-very high mutation rate per locus per generation
-very high levels of polymorphism in a population
-very low probability of finding the same length variant in unrelated individuals
-by analysis of a sufficient number of loci, we can make a 'unique' DNA profile

10

what is the ames test? how does it work?

a screening for potential mutagens
assays the ability of chemicals to revert mutant strains of salmonella typhimurium

11

outline the procedure for the ames test

1) 10^8 cells of bacteria auxotrophic for histidine (His-) are spread with liver enzymes on a plate lacking histidine
2) to grow, the His- must revert to His+

12

which mutations are most and least likely to cause His- to revert to His+?

most likely: base substitutions
less likely: frameshift mutations
least likely: deletions

13

how is reversion frequency calculated?

number of revertant colonies/total number of cells plated

14

outline the DNA damage response

sensor proteins -> signalling cascade -> transducer proteins -> mediator proteins/effector proteins -> apoptosis or senescence

15

how do the cell cycle checkpoints prevent error?

G1, G2 and M cause senescence until DNA damage is repaired