Exam 2 part 4 Flashcards Preview

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Flashcards in Exam 2 part 4 Deck (15)
1

Genic sex determination

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

2

Genotypic sex determination

combination of sex chromosomes determine the sex of that individual

3

y determining mechanism

presence of y chromosome dictates male vs female

4

pseudoautosomal regions

PARs. aligns with the X chromosome during meiotic synapses

5

Male-specific region of the y

MSY
euchromatin has about 50-60 genes involved in sex determination

6

Sex-determining region of y

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

7

XY females

has deletions in y chromosomes

8

XX male

small pieces of y chromosome attached to X
same chromosome region is involved in both instances

9

Barr bodies

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

10

#of Barr bodies in somatic cells

total #X chromosome-1

11

lyonization

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

12

Sex-linked traits in humans

x-linked recessive inheritance
x-linked dominant inheritance

13

sex-linked genes

genes on X or Y chromosome
many linked genes are "innocent passengers"

14

X-linked recessive inheritance

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

15

X-linked dominant alleles

very few traits idenified (faulty teeth enamel)