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ANAT 381 Experimental Embryology > Making embryos > Flashcards

Making embryos Flashcards

1
Q

What are the three steps of fertilization?

A

Penetration through the cumulus cell matrix
Penetration through the zona pellucida
Fusion with the egg plasma membrane

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2
Q

How is the cumulus cell matrix tightly bound?

A

Cell adhesion proteins and hyaluronic acid

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3
Q

What triggers the release of EGF receptor ligands by mural granulosa cells?

A

LH

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4
Q

How is hyaluronic acid released?

A

Pro-factors and ligands upregulate the transcription of genes

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5
Q

What is the role of sperm-specific hyaluronidases?

A

They surround the surface of the sperm and digest the hyaluronic acid, allowing the sperm to get through the matrix

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6
Q

How many proteins are found in the zona pellucida in primates?

A

Four

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7
Q

Deletion of which zp proteins prevents assembly of zona?

A

zp2 and zp3

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8
Q

What test can be done to observe the role of zp2 in fertilization?

A

Replace mouse zp gene by human homologue; mix transgenic mouse egg with human sperm -> sperm doesn’t stick to the zona of mouse egg BUT sticks to zp2 of human egg

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9
Q

What sperm membrane protein is required for sperm-egg fusion?

A

Izumo

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10
Q

Izumo gene activation leads to _____________ males and _____________ females

A

Infertile; fertile

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11
Q

True or false: Izumo knockout leads to the inability for sperm to stick to the membrane

A

False, it disables sperm from fusing into the membrane while still being able to stick to the membrane

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12
Q

What egg membrane protein is required for sperm-egg fusion?

A

Juno

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13
Q

Juno binds to ___________

A

Izumo

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14
Q

Fluorescent Izumo no longer binds to __________ because anti-_____________ antibody covers ____________

A

Juno; Juno; Juno

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15
Q

Deleting Juno from males led to no _____________ and deleting Juno from females led to no _______________

A

Effect; fertilization

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16
Q

What is another membrane protein required for sperm-egg fusion?

A

CD9

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17
Q

CD9 is a member of ________________ cell surface protein family

A

Tetraspanin

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18
Q

CD9 gene inactivation leads to ____________ males and severely sub-fertile _______________

A

Fertile; females

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19
Q

What is the role of CD9 in fertilization?

A

CD9 aggregates Juno proteins on the cell surface for easier targeting of Izumo on the sperm

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20
Q

Which of the following is part of the activation of the egg?
a) Initiation of mitotic cell cycles of embryo
b) Completion of the first meiotic division

A

a)

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21
Q

How is the increase of intracellular calcium linked to the mechanism of activation?

A

Sperm penetration induces repetitive release of calcium ions
Parthenogenetic stimuli induce calcium release
Inhibiting release of calcium prevents activation of the egg

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22
Q

How does the sperm trigger calcium release in the egg?

A

Sperm acts as a ligand to activate intracellular signaling pathway
Sperm component enters oocyte cytoplasm, triggers calcium release

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23
Q

How are G-protein coupled receptors and phospholipase C linked to calcium release?

A

G-protein binds to GPCR and triggers phospholipase C to break down PIP3 into IP3 and diacylglycerol
IP3 triggers the calcium release

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24
Q

True or false: Sperm specific phospholipase C is required for release in the egg

A

True

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25
Q

Is sperm release linked to GPCR?

A

No, sperm releases its own phospholipase C

26
Q

Where can polyspermic fertilization be blocked?

A

Zona pellucida and membrane of egg

27
Q

Calcium released at fertilization triggers cortical granule _______________

A

Exocytosis

28
Q

Cortical granules are responsible for modifying _________ so that sperm can no longer bind to the zona

A

zp2

29
Q

What protein cleaves zp2 at the disulfide bonds and modifies the zona pellucida?

A

Ovastacin

30
Q

When does meiosis II occur in the egg?

A

After fertilization

31
Q

How many polar bodies are formed after fertilization?

A

Two

32
Q

At which phases of meiosis is cohesin degraded?

A

Anaphase I and II

33
Q

How is separase activated?

A

CDC20 and APC form a complex that activates separase by separating it from securin

34
Q

What inhibits the CDC20/APC complex in the first meiotic division?

A

Spindle assembly checkpoint

35
Q

What inhibits the CDC20/APC complex in the second meiotic division?

A

EMI2

36
Q

What causes the degradation of EMI2?

A

Calcium

37
Q

During the first period of DNA replication, chromosomes from egg and sperm are _____________ in the oocyte

A

Separate

38
Q

Histones replace ______________ in sperm chromatin __________ fertilization

A

Protamines; after

39
Q

The period of development before implantation into the uterus lasts _______ days

A

Five

40
Q

Cleavage divisions produce an embryo containing ____________ cells

A

50-100

41
Q

What is morula?

A

Cells are flattened against each other to increase surface area

42
Q

When does activation of embryonic transcription occur in humans and in mouse?

A

Major activation occurs at 2-cell stage in mouse, 4-cell stage in humans

43
Q

Which cells form the blastocyst?

A

Epiblast (primitive ectoderm) and primitive endoderm (inner cell mass) + trophectoderm

44
Q

The primitive ectoderm gives rise to which cell types?

A

All tissues of the embryo, amnion, allantois, yolk sac mesoderm

45
Q

The primitive endoderm gives rise to which cell type?

A

Yolk sac endoderm

46
Q

The trophectoderm gives rise to which cell type?

A

Fetal portion of placenta

47
Q

What are the two models that determine the fate of inner and outer cells?

A

Inside-outside model where fate is determined by position
Polarity model where differential inheritance of polarity domains determine cell fate

48
Q

What is the Hippo signaling pathway?

A

Mob1 and LATS1/2 is activated when MST1/2 and SAV1 are phosphorylated and ubiquitinates YAP/TAZ complex for degradation

49
Q

When the hippo signaling pathway is off, the YAP/TAZ complex is ______________

A

Activated

50
Q

If Hippo is off and YAP is stabilized, which cell type is formed?

A

Trophectoderm

51
Q

If Hippo is on and YAP is degraded, which cell type is formed?

A

Inner cell mass

52
Q

AMOT cannot recruit the machinery that phosphorylates YAP in the _____________ domain

A

Apical

53
Q

AMOT can recruit the machinery that phosphorylates YAP in the _________________ domain

A

Basolateral

54
Q

FGF signaling differentiates primitive ectoderm and primitive ______________

A

Endoderm

55
Q

The epiblast expresses ___________ while the primitive endoderm expresses ________________

A

Nanog; Gata6

56
Q

Why is X-chromosome inactivated?

A

To equalize the gene dosage

57
Q

One X-chr becomes inactivated in _________ and a single X-chr remains active in ____________

A

Females; males

58
Q

What is the mechanism of X-chr inactivation?

A

Xist RNA is expressed from one X-chromosome
Xist RNA coats that X-chr
Xist-coated X is transcriptionally inactive

59
Q

When does X-chr inactivation occur?

A

After implantation

60
Q

Some genes are ___________ and escape inactivation

A

Conserved

ANAT 381 Experimental Embryology (24 decks)

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