1-17 Genetic Variations

Question 1

isozymes

Answer 1

distinguishable proteins with the same or similar enzymatic activity

Question 2

polymorphisms

Answer 2

ocurrence of two or more allelic traits in a popluation with frequences of at least 1-2%

cant simply be accounted for by random mutations in a gene, they are inherited and stable

Question 3

single nucleotide polymorphisms (SNP)

Answer 3

substitution of one base for another, may be conservative/synonyouse (no change in AA), occurs every 100-200 base pairs, heterozygosity occurs every 250-500 base pairs

individuals may be heterozygous at 6-12 million sites

Question 4

cholinesterase

Answer 4

normal variations in humans, but one form has very reduced ability to break down dibucaine (anaesthetic) and leads to paralysis of body while becoming consious

Question 5

apolipoprotein B-100

Answer 5

sole lipoprotien in LDL, ligand which delivers cholesterol to all tissues by the LDL-receptor pathway

common SNPs seen in population, but having homozygous SNPs of one sort is associated with higher cholesterol (pathologically so)

Question 6

How to detect polymorphisms?

Answer 6

at level of protein: 1. elecrophoretic mobility, Km, thermostability, other biophysical protpertias

at level of gene: sequence change in an exon

at level of genome: SNPs, short tandem repeats (microsatellites)

Question 7

Possible consequences of polymorphisms

Answer 7

1. no phenotypic effect
2. normal variations (haptoglobin, peptidase)
3. disease susceptibility (cholinesterase, apoB100)
4. Disease (monogenic)