Fertilization Flashcards Preview

Developmental Biology > Fertilization > Flashcards

Flashcards in Fertilization Deck (25)
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1
Q

What are layers in an invertebrate egg?

A

Jelly layer, viteline envelope, cell membrane, cortical granule layer, nucleus

2
Q

What are layers in a vertebrate egg?

A

ECM with cumulus cells, zona pelucida, periviteline space, nucleus

3
Q

What are the five steps of recognition between sperm and egg in invertebrates (sea urchins)?

A
  1. Sperm contacts jelly layer
  2. Acrosome reaction
  3. Digestion of the jelly layer
  4. Binding to viteline envelope
  5. fusion of acrosomal membrane to egg membrane
4
Q

What are the five steps of recognition between sperm and egg in vertebrates (mouse)?

A
  1. Sperm activated by female reproduction tract
  2. Sperm binds to zona pelucida
  3. Acrosome reaction
  4. Sperm lyses hole in zona pelucida
  5. Sperm and egg membranes fuse
5
Q

Define chemotaxis

A

Movement along a chemical gradient signal

6
Q

How does chemotaxis work in sperm (sea urchin)?

A

The chemical sent from source binds to a receptor, turns on calcium influx, causes swimming in that direction

7
Q

What two types of taxis are utilized to guide sperm to egg in vertebrates?

A

Chemotaxis and thermotaxis

8
Q

What has a longer range, thermotaxis or chemotaxis?

A

thermotaxis

9
Q

What is the name of the thermotactic receptor?

A

TRPM8

10
Q

What are the muscular contractions of the female reproductive tract that push sperm closer to the egg?

A

Peristolsis

11
Q

What is the role of lectin in the acrosome reaction in invertebrates?

A

Lectin receptors cover the outside of the sperm head. Molecules in the jelly layer fill the receptors, activating the acrosomal reaction

12
Q

What is the role of acrosome enzymes in invertebrates?

A

To dissolve the jelly layer?

13
Q

What is the role of the acrosome reaction?

A
  1. To dissolve the jelly layer

2. To extend an actin microfilament covered in bindin

14
Q

What is the role of bindin in fertilization?

A

Species-specific recognition factor required for binding to viteline envelope

15
Q

What is ZP3 in mammals?

A

A factor found in the zona pelucida of the egg that triggers the acrosomal reaction in the sperm

16
Q

Is ZP3 the only factor that triggers acrosomal reaction and fertilization?

A

No. other interactions with sugars on the ZP3 have also been found to be of importance

17
Q

After the acrosomal reaction has occurred in mammals, what is left of the sperm?

A

A covering filled with receptors for ZP1 and ZP2

18
Q

Is ZP3 always required to get acrosome reaction?

A

No. It has been demonstrated.

19
Q

What is the difference between fusion in vertebrates and fusion in invertebrates?

A

Invertebrates is like a missile hitting the ground: vertebrates is like a plane landing

20
Q

Define fast block

A

OCCURS ONLY IN INVERTEBRATES!
Upon fertilization by first sperm, action potential goes over the entire egg, changing charge of surface and repelling sperm

21
Q

Define slow block

A
  1. Also called cortical granule reaction
  2. Upon fertilization, cortical granules are released that form a barrier in the viteline layer.
  3. Dependent on Ca2+
  4. Occurs in both vertebrates and invertebrates
22
Q

In mammals, what factor is required for slow block?

A

ZP2

23
Q

What are roles of calcium influx in sea urchin egg fertilization? (4)

A
  1. slow block,
  2. Reinitiation of the cell cycle
  3. Formation of the hyaline layer
  4. Stimulation of protein synthesis, DNA rep, etc.
24
Q

The cortical granule reaction creates what layer?

A

The hyaline layer

25
Q

What is a role of Ca2+ in mammals exclusively?

A

Signals budding off of polar body