13 Genetic variation

Question 1

What are the three types of mutations?

Answer 1

missense -> diff aa
nonsense -> stop codon
silent -> same aa

Question 2

what are the results of an indel mutation

Answer 2

short ones change sequence
long ones changes genes

may frame shift in some cases

Question 3

what 2 negative effects can muts in non coding site cause?

Answer 3

affect mRNA expression

• promotor
• enhancer/silencer

affect processing
- splice sites

Question 4

what are transposons?

Answer 4

they are mobile genetic elements that jump around randomly -> disruptive in some cases

Question 5

what are three types of Hemoglobin mutations?

Answer 5

sick cell anemia -> structural mut-> glut 6 to val

thalassemia -> expression of globin -> lacking alpha or beta

HPFH -> expression of adult Hb -> fetal Hb persistence

Question 6

what does excess globins form in thalassemias?

Answer 6

in alpha -> excess beta will form tetramers which have reduced ability to carry oxygen

beta thal -> alpha globs will precip -> damages rbc

Question 7

what are two things about ionizing rads

Answer 7

reactive radicals that attack bases are formed

DS DNA breaks

Question 8

what are two things about non ionizing rads

Answer 8

shifts electrons that will cause rxn

pyrimidine dimers form (ie UV)

Question 9

what are two ways chems can damage DNA

Answer 9

base analogues wreak havoc on sequence

deamination can convert C to U

Question 10

what are three considerations that affect mutation rate?

Answer 10

size of gene

age at reproduction

hot pots -> CpG islands methylation (methyl C deams to T)

Question 11

what causes xeroderma pigmentosum and what results?

Answer 11

mut in nucleotide excision repair -> cannot rep pyrimidine dimers

UV causes excessive damage

Question 12

Blood groups are considered what type of variation?

Answer 12

polymorphism

Question 13

what are safety issues with Rh- mothers?

Answer 13

if first child was Rh+ the second child is at risk if also Rh+ due to Rh+ Ab

Question 14

what two conclusions can be made with gene frequency?

Answer 14

chances of two carriers mating

number of affected expected to be seen

Question 15

what assumption needs to be made to apply the hardy weinberg rule and what does it predict?

Answer 15

assumes random mating

esti. freq of gene variants

Question 16

what is the Hardy Weinberg equation?

Answer 16

p2+2pq+q2=1

p = freq norm
q = freq mut
q2 = freq affected

only q or p needed to solve for others

Question 17

what are the four effects of basic population genetics?

Answer 17

natural selection

genetic drift

gene flow

founder effect

Question 18

how are malaria and sickle cell in the subsaharan africa a classic example of selective advantage in gene frequency?

Answer 18

sickle cell will inhibit malaria from infecting affected pts. –> heterozygous for sickle cell pt feel less of the sickle cell symptoms and retain benefits against malaria -> more likely to pass on allele