Exam 2

Question 1

Hemizygous

Answer 1

In a diploid organism, the presence of only one copy of a gene.

Question 2

Heterogametic chromosomes

Answer 2

XY chromosomes

Question 3

What drives Maleness and Femaleness ?

Answer 3

there are genes on the X chromosome that drive “femaleness”, and ALSO genes that can drive “maleness” – but the male genes are only activated if genes on the Y chromosome are expressed.

Question 4

cortex tissue

Answer 4

outer tissue, may develop into an ovary

Question 5

medulla tissue

Answer 5

inner tissue, may develop into testis

Question 6

bipontetial gonads

Answer 6

gonadal ridges that can either form testis or ovaries

Question 7

pseudoautosomal regions (PAR’s)

Answer 7

-present on both ends of the y chromosomes
-share homology with regions on the X chromosome
(synapse and recombine with it during meiosis)

Question 8

TDF

Answer 8

• Testis determining factor
• transcription factor that activates expression of many other genes even on X chromosomes

“located on the Y chromosome but influences expression of genes on the X chromosome”

Question 9

What leads to male differentiation?

Answer 9

Expression of genes on Y chromosome leads to male differentiation

SRY expression leads to testes development

Question 10

SRY genes code for ?

Answer 10

TDF