Exam 1: Lecture 5

Question 1

what is the gene that encodes protein TDS

Answer 1

SRY

Question 2

during which stage we haploid

Answer 2

meiosis/gametes

Question 3

during which stage are we diploid

Answer 3

fertilization/zygote

Question 4

heterogametic mean

Answer 4

sex produces 2 different gamete types with 2 different sex chromosomes

Question 5

T/F: most mammals have 2 sexual phenotypes: m and F

Answer 5

true

Question 6

when is having 1 sexual phenotype advantageous?

Answer 6

when the environment is stable and no genetic variation is needed

Question 7

what is the pairing region for in X and Y chromosomes

Answer 7

the X and Y chromosomes pair during meiosis bc small region of shared homology

Question 8

A male with a recessive mutation on his X chromosome means what

Answer 8

No counterpart on the Y so not able to make working gene so any defective genes on his X they become pseudo dominant and will express (phenotypically)

Y carries no balancing genes so susceptible to defects

Question 9

hermaphroditism

Answer 9

both sexes in same organism

Question 10

monoecious

Answer 10

both m and f reproductive structures in the same organism

Question 11

dioecious

Answer 11

either m or female reproductive structures but not both in 1 organism

Question 12

XX-XO system:

Answer 12

dosage system. 1 X is the threshold to be a male

Question 13

ZW-ZZ system:

Answer 13

females are heterogametic

Question 14

why is the Y seen as a “flip switcher”

Answer 14

default is female but if get an Y, switch is made to male

Question 15

the pseudoautosomal regions are located where on a chromosome

Answer 15

at the tips

Question 16

how does the heterogametic sex differ from the homogametic sex

Answer 16

gametes of teh heterogametic sex have different sex chromosomes; gametes of homogametic sex have the same sex chromosome

Question 17

turner syndrome:

Answer 17

XO

Question 18

klinefelter syndrom

Answer 18

XXY, XXXY, XXXXY, XXYY

single Y will be male no matter number of Xs

Question 19

androgen-insensitivity syndrome

Answer 19

caused by defective androgen receptor

Question 20

where is the SRY gene located on a chromosome

Answer 20

short arm of Y chromosome

Question 21

y linked characteristics

Answer 21

• only present in males
• all male offspring will exhibit the trait
• Y chromosome lost DNA over time
• sex determination in SRY

Question 22

x linked characteristics

Answer 22

mutation in a gene of the x chromosome causes phenotype to be expressed in males (hemizygous for the gene mutation)

Question 23

mary lyon

Answer 23

cell line will have same x chromosome inactivated throughout

Question 24

mosaicism

Answer 24

different tissues have mom or dad x chromosome active

Question 25

Xic

Answer 25

x inactivation centers are counted; xist is turned on and its RNA product coats one of X chromosomes

Question 26

can xic be undone?

Answer 26

yes; during meiosis (recurring cycle in female development)

Question 27

what are the 2 important recessive x linked disorders?

Answer 27

red-green color blindness and DMD