Exam 2 part 4

Question 1

Genic sex determination

Answer 1

single allele at a gene locus determines the sex of that individual
ex. yeast a or alpha

Question 2

Genotypic sex determination

Answer 2

combination of sex chromosomes determine the sex of that individual

Question 3

y determining mechanism

Answer 3

presence of y chromosome dictates male vs female

Question 4

pseudoautosomal regions

Answer 4

PARs. aligns with the X chromosome during meiotic synapses

Question 5

Male-specific region of the y

Answer 5

MSY

euchromatin has about 50-60 genes involved in sex determination

Question 6

Sex-determining region of y

Answer 6

SRY
becomings active at about 6-8 weeks during development
encodes testes determining factor (TDF)
control testes development
absence of TDF means gonads will develop into ovaries

Question 7

XY females

Answer 7

has deletions in y chromosomes

Question 8

XX male

Answer 8

small pieces of y chromosome attached to X

same chromosome region is involved in both instances

Question 9

Barr bodies

Answer 9

gene dosage compensation
silencing of 1 X chromosome in females allows for the same level of expression for genes in X chromosome in males and females

Question 10

of Barr bodies in somatic cells

Answer 10

total #X chromosome-1

Question 11

lyonization

Answer 11

one x chromosome is changed from euchromatin to heterochromatin about 16 days after fertilization
occurs randomly between 2 x chromosomes

Question 12

Sex-linked traits in humans

Answer 12

x-linked recessive inheritance

x-linked dominant inheritance

Question 13

sex-linked genes

Answer 13

genes on X or Y chromosome

many linked genes are “innocent passengers”

Question 14

X-linked recessive inheritance

Answer 14

trait occurs more frequently in males
–males are hemizygous for genes on x chromosome
females express the trait when they are homozygous for the allele
–female hets are carriers

Question 15

X-linked dominant alleles

Answer 15

very few traits idenified (faulty teeth enamel)