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Repro Class Notes > Week 1 > Flashcards

Week 1 Flashcards

1
Q

what pairs together in meiosis 1

A

Homologous chromosomes

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2
Q

what is a key event that happens during meisis

A

recombination

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3
Q

t/f at the end of meosis homologous chromosomes recombine

A

true

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4
Q

how many possiibilities for a gamete

A

64 million

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5
Q

when does sex determination occur

A

it occurs at fertilization

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6
Q

what are the 3 aspects of sex determination

A
  1. establishment of chromosomal sex- xy or xx
  2. initiation of alternate pathways to differentiaton of one or the other gonadal sex . this is determined by the y chromosome ( happens after 7 weeks)
  3. sex differentiation into internal and external organs after puberty
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7
Q

what is sexual determination

A

related to the genetic make up at fertilization

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8
Q

the events after the gonadal sex is also known as

A

sexual differentiation

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9
Q

what chromosomes specify the gonadal and chromosomal sex

A

sex chromosomes

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10
Q

t/f the genes for sex determination are located on the sex chromosome and autosomes

A

true

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11
Q

gonads differentiate into testis or ovaries depending on what

A

the presense or absence of the y chromosome

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12
Q

if the y gene is present bu the sry gene is mutated what will happen

A

ovaries will develop

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13
Q

which chromosome is shorter x or y

A

the y is shorter , it has less than 100 genes

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14
Q

most of the y chromosome is made up of what

A

MSY aka male specific region

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15
Q

gonads differentiate into testis or ovaries depending on the presence or absence of what

A

y chromosome

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16
Q

what is most of the y chromosome called

A

MSY or male specific region

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17
Q

what region of the y chromosome has homology to the x chromosome

A

the pseudoautosomal regions at the ends of the p and q arms

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18
Q

does the msy region of the y chromosome recombine with x chromosome

A

no

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19
Q

when do we see gross morphological differences between sexes

A

the 7th week of gestation

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20
Q

the early period from 0-7 weeks is called what

A

the indifferent stage

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21
Q

what is the only factor that determines if testies will develop or ovaries

A

the y chromosome with a functional SRY gene

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22
Q

what happens to the x chromosomes in females

A

one of the x chromosomes gets inactivated . it is random

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23
Q

how can an inactivated x chromosome be identified

A

barr body in interphase cells

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24
Q

a female is 48 xxxx how many barr bodies will she have

A

3

25
Q

what inactivates the x chromosome

A

x inactivation transcript

26
Q

what kind of histones are on the inactive x

A

enriched with macro H2A

27
Q

what is an aneuploidy

A

any variation in the normal chromosome number

28
Q

what is the most common aneuploidy in males

A

klinefelter syndrome

29
Q

what does klinefelter syndrome mean

A

the wrong number of x chromosomes

30
Q

what are key features of klinefelter syndrome

A

tall, learning difficulties, hypogonadism. infertile

31
Q

how do most adults get diagnosed with klinefelters

A

low sperm count makes them infertile

32
Q

what are 3 key features of adults with klinefelters

A

loss of libido
loss of muscle tone
infertile

33
Q

what is a way to tell klinefelters from xyy

A

xyy are not infertile

klinefelters are infertile

34
Q

what kind of syndrome is 45 x

A

turner syndrome

35
Q

what kind of syndrome is 46x, xq

A

turner

36
Q

what is gonadal dysgenesis

A

46 xy. they are raised female because the sry. portion of the y chromosome is functional

37
Q

what does a person with turners syndrome look like

A

short webbed neck, infantile lymphedema, coarctation of the aorta

38
Q

what are key features of someone with 47 xxx

A

low iq . the more x chromosomes the worse the outcome

39
Q

what is the main cause of 47 xxx

A

an error in meiosis 1

40
Q

whats the first step to do if someone has ambigous genetalia

A

karyotype

41
Q

when is the sry gene expressed

A

it is expressed only briefly in the germinal ridges just before testies differentiation

42
Q

what kind of gene is the SRY gene

A

transcription factor responsible for the initiation of the male sex determination

43
Q

what does the SRY gene regulate

A

it regulates SOX 9 it is an autosomal gene leading to testies development

44
Q

if there is a mutation is the SRY gene which pathway will always occur

A

ovaries

45
Q

what does daz 1 do

A

anti-testies gene

46
Q

for a person with DAX1 duplication what will they look like what will thier karyotype be

A

they will look like a female because lots of anti testies factor. but they are xy

47
Q

what is the exact pathway for testies development

A

sry gene is present, it works on the sox9 gene and develops testies

48
Q

what is the exact pathway for ovary development

A

no sry present , sox 9 is not turned on so ovaries develop

49
Q

in females what makes sure that sox 9 does not get expressed

A

beta catanin

50
Q

when are human primordial germ cells recognizable

A

4th week

51
Q

what happens to human primordial germ cells by the 6th week

A

they migrate to the genital ridges

52
Q

spermatogeneis and oorgeneis both require what

A

meisosis

53
Q

spermatogeneis and oorgeneis both require what

A

meisosis

54
Q

spermatogeneis and oorgeneis both require what

A

meisosis

55
Q

when is meiosis initiated in females

A

once in females during fetal life.

continuously in males throuoghout the adult life

56
Q

what is the ploidy # of secondary spermatocyte

A

haploid

57
Q

where are primary oocytes formed in females

A

follicles

58
Q

what makes something a polar body

A

no cytoplasm

59
Q

what phase is finished during ovulation

A

meiosis 1

Repro Class Notes (9 decks)

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