Chromosomal Inheritance I

Question 1

X inactivation

Answer 1

one of 2 X chromosomes in each cell is randomly inactivated during embryonic dev
if heterozygous for a gene on X chromosome—> mosaic

Question 2

Unlinked genes

Answer 2

assort independently

50% recombo freq

Question 3

Perfectly linked genes

Answer 3

no recombos!!

Question 4

what ptypic ratio expected if genes on diff chrom, how abt perfeclty linked?

Answer 4

unlinked: 1:1:1:1

perf linked: 1:1

Question 5

What conclusion did morgan come to after testcross of wildtype and mutants

Answer 5

body color and wing size are usually inherited together in specific combo since genes are on same chrom
recombos were produced so genes were linked, but incomplete linkage
crossing over breaks physical connection btwn genes on same chromosome

Question 6

define genetic map

Answer 6

order of genes on chromosome

Question 7

define recombo freq

Answer 7

measure of distance between genes

the higher the recombo, the more genetically distant

Question 8

what is max freq of recombos btwn 2 genes?

Answer 8

50%

independent assortment
as if on two diff chrom

Question 9

what can explain discrepency bewtn recombo and crossover freq

Answer 9

multiple crossovers are common between far loci, larger genetic distances
recombo freq only ~ genetic distance if loci are close

Question 10

linkage map vs physical map

Answer 10

linkage map depends on recombo freq only

physical map is actual order of genes based on bp distances

Question 11

why is spacing of genes betwen genetic map and physical map not identical?

Answer 11

some loci that are far can have not many crossovers or

loci that are close may have many crossovers

Question 12

T/F: linkage is the mechanistic basis of how we discover genes that cause diseases

Answer 12

T

Question 13

GWAS

Answer 13

two groups, 1 control 1 diseased. compare seq i.e. look for SNPs that account for ptypic diff