Fertilization

Question 1

What are layers in an invertebrate egg?

Answer 1

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

Question 2

What are layers in a vertebrate egg?

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

Define chemotaxis

Answer 5

Movement along a chemical gradient signal

Question 6

How does chemotaxis work in sperm (sea urchin)?

Answer 6

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

Question 7

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

Answer 7

Chemotaxis and thermotaxis

Question 8

What has a longer range, thermotaxis or chemotaxis?

Answer 8

thermotaxis

Question 9

What is the name of the thermotactic receptor?

Answer 9

TRPM8

Question 10

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

Answer 10

Peristolsis

Question 11

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

Answer 11

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

Question 12

What is the role of acrosome enzymes in invertebrates?

Answer 12

To dissolve the jelly layer?

Question 13

What is the role of the acrosome reaction?

Answer 13

1. To dissolve the jelly layer

2. To extend an actin microfilament covered in bindin

Question 14

What is the role of bindin in fertilization?

Answer 14

Species-specific recognition factor required for binding to viteline envelope

Question 15

What is ZP3 in mammals?

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

A covering filled with receptors for ZP1 and ZP2

Question 18

Is ZP3 always required to get acrosome reaction?

Answer 18

No. It has been demonstrated.

Question 19

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

Answer 19

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

Question 20

Define fast block

Answer 20

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

Question 21

Define slow block

Answer 21

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

Question 22

In mammals, what factor is required for slow block?

Answer 22

ZP2

Question 23

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

Answer 23

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

Question 24

The cortical granule reaction creates what layer?

Answer 24

The hyaline layer

Question 25

What is a role of Ca2+ in mammals exclusively?

Answer 25

Signals budding off of polar body