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Undeleted > Lecture 6 > Flashcards

Lecture 6 Flashcards

0
Q

contains one set of chromosomes

A

haploid

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1
Q

contains two sets of chromsomes, one from each parent

A

diploid

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2
Q

specialized reproductive cells; sperm or eggs gerneated through meiosis

A

gametes

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3
Q

haploid gametes fuse to fomr a diploid cell (Zygote)

A

fertilization

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4
Q

divided by mitosis to become a multipcellular organism

A

zygote

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5
Q

gametes and their precursors

A

gerline cells

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6
Q

form the rest of the body and leave no progeny

A

somatic cells

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7
Q

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

A

autosomes

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8
Q

X and Y

A

sex chromosomes

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9
Q

meiosis creates what two genetic diversity?

A

Random segregation of homologs during meiosis and crossing over

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10
Q

gametes are?

A

haploid

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11
Q

What arise from meiosis?

A

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

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12
Q

When do chromosomes replicate?

A

S phase

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13
Q

How are two chromatids bound?

A

cohesion complexes

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14
Q

What does homologs do in meiosis I

A

pair ,recombine, and separate

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15
Q

seperation of homologs in meiosis?

A

anaphase I

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16
Q

Meiosis II DNA replication?

A

none

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17
Q

divided to produce 4 haploid duahgter cells?

A

sister chromatids in meiosis II

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18
Q

When do homlogs begin to pair?

A

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

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19
Q

What is a 4 chromatid structure?

A

bivalent

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20
Q

What does a stable piaring require crossing over?

A

chiasma

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21
Q

What are hologs joined by protein strucutre?

A

synaptonemal complex

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22
Q

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

A

pseudoautosomal region

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23
Q

homlogs begin to condesne/pair

A

leptotene

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24
Q

homologs pair and synaptonemal complexes form

A

zygotene

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25
Q

synapsis is complete; crossing over occurs

A

pachytene

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26
Q

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

A

diplotene

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27
Q

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

A

diakinesis

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28
Q

What do transvers filaments btw homlogs form?

A

synaptonemal complex, important for crossing over

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29
Q

When do cohesin compelxes assemble on DNA?

A

during S phase and bind sister chromatids

  • major components of axial core of each homolog
  • play important role in segregating homlogs in meiosis I
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30
Q

What attach to microtubules coming form same pole?

A

kinetochores on the 2 sister chromatids

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31
Q

When do homlogs separate?

A

anaphase I

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32
Q

Arms of sitster chromatids separate at anaphase I,

A

resolving chiasmata and allowing homlogs to seperate

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33
Q

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

A

separase

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34
Q

When is human female meiossi arrestes for years after diplotene?

A

meiosis I is completed only at ovulation

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35
Q

memiosis II in females is only completed after?

A

fertilization

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36
Q

homlogs fail to spearate properly

A

nondisjunction

  • erros are very common during egg development and increase with advanceing maternal age
  • leading cause of spontaneous abortions and metal retardation in humans
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37
Q

cells with abnormal choromsome numbers

A

aneuploid

  • trsomey 21/down syndrom: most common singl cause of metal retardation
  • 90% of trisomy 21 individsual, the additional chromsomes is materal in orgin
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38
Q

cells with normal number of chromsomes

A

euploid

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39
Q

random distirbution of maternal/paternal homlogs can produe?

A

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

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40
Q

What is variation increased by?

A

crossing over.

-2-3 crossovers per human homolog

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41
Q

Female mammals begin meiosis in?

A

the fetal ovary

  • arrest in meiosis I
  • meosis 1 completed at ovulation
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42
Q

In males meiosis being in the testes at?

A

puberty

  • proceeds without arres
  • takes 24 days to complete meiosis
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43
Q

20% of eggs are aneuploid vs

A

only 3 to 4% of sperm

- a cell cycle checkpoint is activated in sperm w metiotic errors, resultiping in apoptosis

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44
Q

25% of all human conceptions are aneuploid

A

-mostly due to nondisjunction in oocytes at Meiosis I

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45
Q

What are male gametes more prone to?

A

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

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46
Q

found in all vertebrate embryos and give rise to gametes

A

primordial gemr cells(PGCs)

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47
Q

PGCs cells migrate to deleveoping gonads

A

ovaries/testes

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48
Q

intially germ cells go through

A

mitosis

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49
Q

in mammals, diving egg is totipotnet fo?

A

fist few rounds of cell division; then differentiate into PGCs

50
Q

somatic cell fates must be suppressed by?

A

gene repression

51
Q

Translation of certain RNAs must be?

A

inhibited

52
Q

p granules

A

accumulate at pole after fertiliation and?

53
Q

cell signaling lead to ? in gonaldal development

A

proliferation and migration of PGCs to developing gonad

-genital ridge

54
Q

uncommitted to cell fate

A

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
Q

sex chromsomes in genital ridege determine?

A

if gonad…

56
Q

Female

A

46, XX

57
Q

Males

A

46, XY

58
Q

Sperm determines sex of

A

embryo

  • presence of absence of Y determines sex of indvidual
  • 45, X patients are still female
59
Q

Y directs?

A

genital ridge to develop into testis

-default pathway is female

60
Q

sex determining region of Y

A

SRY

61
Q

necessary and sufficient for testis development in mammals

A

SRY Gene

62
Q

can cause sex reverasl

  • XX mouse + SRY= develops as a male(sterile)
  • XY male w inactivating SRY mutation=develops as female
A

SRY gene

63
Q

differntiate into Sertolie cells

A

expression of SRY

-testis supprot cells

64
Q

SRY

A

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

65
Q

What is expressed in all vertebreates?

A

Sox9

66
Q

Sox 9

A

…

67
Q

What does SRY in somatic cells do?

A

direct differentitation into sertolie cells instead of follicle cells

68
Q

What doe sertolie cells secrete?

A

anti mullerian hormone

69
Q

anti-mullerian hormone

A
  • suprresses fmale development

- causees mullerian duct to regress

70
Q

SRY induce

A

leydig cell differentation in other sperm cells

71
Q

activated egg can give rise to completely new organisms

A

eggs

72
Q

What is egg activations triggered by?

A

fertlization- fusion of sperm and egg

73
Q

What occurs in some lizards and frogs?

A

parthenogentic

  • activation in thea bsence of sperm
  • mammals cannot due to imprinting
74
Q

What can be used to reprogram

A

…

75
Q

Eggs contain?

A

stockpiles of nutrients for intial development of the embryo

76
Q

What is the egg nutritional reserve?

A

yolk

  • rich in lipids; protines and polysaccharides
  • yolk grandules; discrete yolk-containing structures
77
Q

What is the egg coat made of?

A

glycoprotien rich extra cellular matrix

78
Q

what does the extra cellular matrix protect from?

A

mechanical damage

79
Q

Oogenesis cells migrate into the gonad?

A

primordial germ cell

80
Q

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

A

diploid oogonia

81
Q

When are primary oocytes fomred?

A

during gestation of the human embryo

82
Q

Primary oocytes arrest at?

A

prophase I of meiosis I

83
Q

When does primary oocytes resume progression?

A

at ovulation

84
Q

How does cytoplams divide in oognesis?

A

asymettrically

  • small polar body
  • large secondary oocyte
85
Q

When is the sendocary oocyte arrested?

A

metaphase II

86
Q

How do eggs achieve lg size?

A

have extra gene copies in the cell

-growth occurs afteer DNA replication

87
Q

How do eggs import yolk proteins?

A

through recetor mediated endocytosis

88
Q

oocyte surrounded by single layer of follicle cells

A

primordial follicles

89
Q

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

A

developing follicles

90
Q

some developing follicels go on to acquire fluid filled cavity

A

antrum

91
Q

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

A

puberty

92
Q

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

A

ovulation and primary oocyte…

93
Q

sperm

A

much smaller

  • stripped down
  • no cytoplamic organlels
94
Q

sperm have two distinct regions

A

head-contains nucleus

tail-propulsino

95
Q

What is the midpiece of a sperm packed wiht?

A

mitochondria to power flagellum for movment

96
Q

What proteins are require in sperm?

A

Dynein motor proteins requre ATP hydorlysis to slide microtubules

97
Q

What does the acrosomal vescile contain?

A

hydrolytic enzymes

  • released by exocytosis in acrome reaction
  • helps penetrate eggs outer coat
98
Q

When does meiosis for sperm begin?

A

puberty

99
Q

When do piared homologs cross over?

A

prophase I of metaphase

100
Q

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

A

two secondary spermatocytes w 22 duplicated autosomes and X or Y

101
Q

What happens to sendodary spermatocytes

A

enters M II to porduce 4 haploid spermatids

102
Q

What happen to spermatids?

A

they differentiate into sperm which escape into lumen of seminiferous tubule

103
Q

Where are sperm stored and undergo further matureation?

A

epididymis

104
Q

sperm development

A

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

105
Q

Where does spermatogenesis occur?

A

seminiferous tubuels

  • maintina close contace with sertoli cells
  • spermatogonia undergo limited mitotic dividison before endering meiosis I
106
Q

Progeny of spermatogonium don’t complete?

A

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
Q

fusion of egg and sperm

A

fertilization

108
Q

process required to acquire capacity to fertilize an egg

A

capacitation

  • takes 5-6 hrs in humans
  • completed in oviduct
109
Q

What does sperm undergo during fertilization?

A
  • greatly increases motility of flagellum

- makes sperm capable of undergoing acrosome reaction

110
Q

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

A

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
Q

What is released egg surrounded in?

A

granulosa cells and ECM rich in hyaluronic acid

112
Q

What must capacitated sperm penetrate?

A

granulosa cells using hyaluronidase

113
Q

WHat does zona pellucida act as?

A

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
Q

What membrane proteins are neded for sperm binding?

A

ZP1 cross- links filaments

ZP 2 and 3 form long filaments

115
Q

Fusion with sperm induces?

A

cortical reaction

  • cortical granules release contents
  • meiosis to resume
116
Q

What is cortical reation triggered by?

A

increased Ca2+ in cytosol

-egg activation can be artificailly triggered by injecting CA2+ into egg

117
Q

Cortical reaction prevents?

A

polyspermy

118
Q

Cortical reaction releases enzymes to change?

A

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
Q

What fuse in the zygote?q

A

2 haploid nuclei (pronuclei)

-forms a single diploid nucleus

120
Q

What do sperm contribute?

A

centrosomes and centrioles

-not present in eggs

121
Q

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

A

extra mitotic spindles are present

-leads to fualty segregation of chromosomes and aneuploidy

122
Q

Reproductive cloning

A

use foster mother to grow identical clone

123
Q

therapeutic cloning

A

lab growth of only certain cells

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