Exam 1: Lecture 5 Flashcards Preview

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Flashcards in Exam 1: Lecture 5 Deck (27)
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1
Q

what is the gene that encodes protein TDS

A

SRY

2
Q

during which stage we haploid

A

meiosis/gametes

3
Q

during which stage are we diploid

A

fertilization/zygote

4
Q

heterogametic mean

A

sex produces 2 different gamete types with 2 different sex chromosomes

5
Q

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

A

true

6
Q

when is having 1 sexual phenotype advantageous?

A

when the environment is stable and no genetic variation is needed

7
Q

what is the pairing region for in X and Y chromosomes

A

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

8
Q

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

A

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

9
Q

hermaphroditism

A

both sexes in same organism

10
Q

monoecious

A

both m and f reproductive structures in the same organism

11
Q

dioecious

A

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

12
Q

XX-XO system:

A

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

13
Q

ZW-ZZ system:

A

females are heterogametic

14
Q

why is the Y seen as a “flip switcher”

A

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

15
Q

the pseudoautosomal regions are located where on a chromosome

A

at the tips

16
Q

how does the heterogametic sex differ from the homogametic sex

A

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

17
Q

turner syndrome:

A

XO

18
Q

klinefelter syndrom

A

XXY, XXXY, XXXXY, XXYY

single Y will be male no matter number of Xs

19
Q

androgen-insensitivity syndrome

A

caused by defective androgen receptor

20
Q

where is the SRY gene located on a chromosome

A

short arm of Y chromosome

21
Q

y linked characteristics

A
  • only present in males
  • all male offspring will exhibit the trait
  • Y chromosome lost DNA over time
  • sex determination in SRY
22
Q

x linked characteristics

A

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

23
Q

mary lyon

A

cell line will have same x chromosome inactivated throughout

24
Q

mosaicism

A

different tissues have mom or dad x chromosome active

25
Q

Xic

A

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

26
Q

can xic be undone?

A

yes; during meiosis (recurring cycle in female development)

27
Q

what are the 2 important recessive x linked disorders?

A

red-green color blindness and DMD