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contains two sets of chromsomes, one from each parent

diploid

1

contains one set of chromosomes

haploid

2

specialized reproductive cells; sperm or eggs gerneated through meiosis

gametes

3

haploid gametes fuse to fomr a diploid cell (Zygote)

fertilization

4

divided by mitosis to become a multipcellular organism

zygote

5

gametes and their precursors

gerline cells

6

form the rest of the body and leave no progeny

somatic cells

7

chromosomes common to both sexes; one from each parent in each diploid nucleus

autosomes

8

X and Y

sex chromosomes

9

meiosis creates what two genetic diversity?

Random segregation of homologs during meiosis and crossing over

10

gametes are?

haploid

11

What arise from meiosis?

involves two cell division buy one round of DNA synthesiss to produce half the number of chromsomes

12

When do chromosomes replicate?

S phase

13

How are two chromatids bound?

cohesion complexes

14

What does homologs do in meiosis I

pair ,recombine, and separate

15

seperation of homologs in meiosis?

anaphase I

16

Meiosis II DNA replication?

none

17

divided to produce 4 haploid duahgter cells?

sister chromatids in meiosis II

18

When do homlogs begin to pair?

in prophase I, which can last weeks /day/ years

19

What is a 4 chromatid structure?

bivalent

20

What does a stable piaring require crossing over?

chiasma

21

What are hologs joined by protein strucutre?

synaptonemal complex

22

What small region of homology btw X and Y allows them to piar?

pseudoautosomal region

23

homlogs begin to condesne/pair

leptotene

24

homologs pair and synaptonemal complexes form

zygotene

25

synapsis is complete; crossing over occurs

pachytene

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synaptonemal complex begins to break down; homologs begin to spearte but remain attached at chiasmata

diplotene

27

reach maximum condensation; separation of homologs and transition stage into metaphase

diakinesis

28

What do transvers filaments btw homlogs form?

synaptonemal complex, important for crossing over

29

When do cohesin compelxes assemble on DNA?

during S phase and bind sister chromatids
-major components of axial core of each homolog
- play important role in segregating homlogs in meiosis I

30

What attach to microtubules coming form same pole?

kinetochores on the 2 sister chromatids

31

When do homlogs separate?

anaphase I

32

Arms of sitster chromatids separate at anaphase I,

resolving chiasmata and allowing homlogs to seperate

33

What cleaves the cohesion complexes in sister chromatids in anaphase II?

separase

34

When is human female meiossi arrestes for years after diplotene?

meiosis I is completed only at ovulation

35

memiosis II in females is only completed after?

fertilization

36

homlogs fail to spearate properly

nondisjunction
-erros are very common during egg development and increase with advanceing maternal age
-leading cause of spontaneous abortions and metal retardation in humans

37

cells with abnormal choromsome numbers

aneuploid
-trsomey 21/down syndrom: most common singl cause of metal retardation
-90% of trisomy 21 individsual, the additional chromsomes is materal in orgin

38

cells with normal number of chromsomes

euploid

39

random distirbution of maternal/paternal homlogs can produe?

2^n(2^23=8.4X10^6)

40

What is variation increased by?

crossing over.
-2-3 crossovers per human homolog

41

Female mammals begin meiosis in?

the fetal ovary
-arrest in meiosis I
-meosis 1 completed at ovulation

42

In males meiosis being in the testes at?

puberty
-proceeds without arres
-takes 24 days to complete meiosis

43

20% of eggs are aneuploid vs

only 3 to 4% of sperm
- a cell cycle checkpoint is activated in sperm w metiotic errors, resultiping in apoptosis

44

25% of all human conceptions are aneuploid

-mostly due to nondisjunction in oocytes at Meiosis I

45

What are male gametes more prone to?

new DNA mutations as a result of undergoing more mitotic cell divisions
-acvanced paternal age

46

found in all vertebrate embryos and give rise to gametes

primordial gemr cells(PGCs)

47

PGCs cells migrate to deleveoping gonads

ovaries/testes

48

intially germ cells go through

mitosis

49

in mammals, diving egg is totipotnet fo?

fist few rounds of cell division; then differentiate into PGCs

50

somatic cell fates must be suppressed by?

gene repression

51

Translation of certain RNAs must be?

inhibited

52

p granules

accumulate at pole after fertiliation and?

53

cell signaling lead to ? in gonaldal development

proliferation and migration of PGCs to developing gonad
-genital ridge

54

uncommitted to cell fate

PGCs
-can be removed and cultured w signaling protines to fomr cell lines for any cell type for the body except extraembryonic cells---pluripotent

55

sex chromsomes in genital ridege determine?

if gonad...

56

Female

46, XX

57

Males

46, XY

58

Sperm determines sex of

embryo
-presence of absence of Y determines sex of indvidual
-45, X patients are still female

59

Y directs?

genital ridge to develop into testis
-default pathway is female

60

sex determining region of Y

SRY

61

necessary and sufficient for testis development in mammals

SRY Gene

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can cause sex reverasl
-XX mouse + SRY= develops as a male(sterile)
-XY male w inactivating SRY mutation=develops as female

SRY gene

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differntiate into Sertolie cells

expression of SRY
-testis supprot cells

64

SRY

encodes DNA biding protein that regulates transctiption of genes involved in Sertolie development

65

What is expressed in all vertebreates?

Sox9

66

Sox 9

...

67

What does SRY in somatic cells do?

direct differentitation into sertolie cells instead of follicle cells

68

What doe sertolie cells secrete?

anti mullerian hormone

69

anti-mullerian hormone

-suprresses fmale development
-causees mullerian duct to regress

70

SRY induce

leydig cell differentation in other sperm cells

71

activated egg can give rise to completely new organisms

eggs

72

What is egg activations triggered by?

fertlization- fusion of sperm and egg

73

What occurs in some lizards and frogs?

parthenogentic
-activation in thea bsence of sperm
-mammals cannot due to imprinting

74

What can be used to reprogram

...

75

Eggs contain?

stockpiles of nutrients for intial development of the embryo

76

What is the egg nutritional reserve?

yolk
-rich in lipids; protines and polysaccharides
-yolk grandules; discrete yolk-containing structures

77

What is the egg coat made of?

glycoprotien rich extra cellular matrix

78

what does the extra cellular matrix protect from?

mechanical damage

79

Oogenesis cells migrate into the gonad?

primordial germ cell

80

What undergo mitotic cell divisions before entering into meiosis in oogenesisi?

diploid oogonia

81

When are primary oocytes fomred?

during gestation of the human embryo

82

Primary oocytes arrest at?

prophase I of meiosis I

83

When does primary oocytes resume progression?

at ovulation

84

How does cytoplams divide in oognesis?

asymettrically
-small polar body
-large secondary oocyte

85

When is the sendocary oocyte arrested?

metaphase II

86

How do eggs achieve lg size?

have extra gene copies in the cell
-growth occurs afteer DNA replication

87

How do eggs import yolk proteins?

through recetor mediated endocytosis

88

oocyte surrounded by single layer of follicle cells

primordial follicles

89

multiple layers of follicle cells(granulosa cells) surround grwoing oocyte

developing follicles

90

some developing follicels go on to acquire fluid filled cavity

antrum

91

FSH surge induces 10-12 antral follicels; one becomes dominate

puberty

92

What does the FSH+LH in middle of menstral cycle trigger?

ovulation and primary oocyte...

93

sperm

much smaller
-stripped down
-no cytoplamic organlels

94

sperm have two distinct regions

head-contains nucleus
tail-propulsino

95

What is the midpiece of a sperm packed wiht?

mitochondria to power flagellum for movment

96

What proteins are require in sperm?

Dynein motor proteins requre ATP hydorlysis to slide microtubules

97

What does the acrosomal vescile contain?

hydrolytic enzymes
-released by exocytosis in acrome reaction
-helps penetrate eggs outer coat

98

When does meiosis for sperm begin?

puberty

99

When do piared homologs cross over?

prophase I of metaphase

100

What do primary spermatocytes produce when they complete M I?.

two secondary spermatocytes w 22 duplicated autosomes and X or Y

101

What happens to sendodary spermatocytes

enters M II to porduce 4 haploid spermatids

102

What happen to spermatids?

they differentiate into sperm which escape into lumen of seminiferous tubule

103

Where are sperm stored and undergo further matureation?

epididymis

104

sperm development

primordial germ cell.... spermatogonium.... primary spermatocyte.... secondary spermatocyte... spermatid... mature sperm

105

Where does spermatogenesis occur?

seminiferous tubuels
-maintina close contace with sertoli cells
-spermatogonia undergo limited mitotic dividison before endering meiosis I

106

Progeny of spermatogonium don't complete?

cytokinesis
-they remain connected through cytoplamic bridges---syncytium
-each share common cytoplasm
-produced in synchronous batches
-have access to diploid genome for their development

107

fusion of egg and sperm

fertilization

108

process required to acquire capacity to fertilize an egg

capacitation
-takes 5-6 hrs in humans
-completed in oviduct

109

What does sperm undergo during fertilization?

-greatly increases motility of flagellum
-makes sperm capable of undergoing acrosome reaction

110

What must be present in female genital tract for fertilization to occur?

albumin- helps extract cholestrerol from membran, increasing ability to fuse with acrosome membrane
-Ca2+ and HCO3- activate adenyl cyclase in sperm to produce cAMP---helps to initiate capacitation-associated changes

111

What is released egg surrounded in?

granulosa cells and ECM rich in hyaluronic acid

112

What must capacitated sperm penetrate?

granulosa cells using hyaluronidase

113

WHat does zona pellucida act as?

species barrier
-induces sperm to undergo acrosome reaction
-help sperm to tunnel
-sperm can bind and fuse w plasma membrane of egg
-sperm binds egg plasma first by tip and then side

114

What membrane proteins are neded for sperm binding?

ZP1 cross- links filaments
ZP 2 and 3 form long filaments

115

Fusion with sperm induces?

cortical reaction
-cortical granules release contents
-meiosis to resume

116

What is cortical reation triggered by?

increased Ca2+ in cytosol
-egg activation can be artificailly triggered by injecting CA2+ into egg

117

Cortical reaction prevents?

polyspermy

118

Cortical reaction releases enzymes to change?

zona pellucida so sperm cant penetrate
-inactivation of ZP3 so it no longer binds sperm or induces acrosoem reaction
-ZP2 is cleaved which makes ZP impenetrable

119

What fuse in the zygote?q

2 haploid nuclei (pronuclei)
-forms a single diploid nucleus

120

What do sperm contribute?

centrosomes and centrioles
-not present in eggs

121

Sperm contribut cetersome for duplicates to assesmble mitotic spindle, in polyspermy

extra mitotic spindles are present
-leads to fualty segregation of chromosomes and aneuploidy

122

Reproductive cloning

use foster mother to grow identical clone

123

therapeutic cloning

lab growth of only certain cells