Fertilization: Sea Urchins & Mammals

Acrosomal process

What structure in the sperm head contains surface molecules for species-specific recognition between sperm and egg?

Digesting the jelly layer

What is the function of the enzymes secreted by the acrosomal process?

Bindin

In sea urchins, ______ is used to bind to the vitelline envelope.

It prompts the acrosome reaction

What does the Ca2+ and pH change triggered by contact with the jelly coat do to the sperm?

Fertilization cone

Name the term for the point of entry of a sperm cell into the egg.

Fertilization envelope

This structure is formed from the vitelline envelope of the sea urchin egg following cortical granule release.

Ca2+

What ion is released from the egg’s internal stores when sperm bonds to it?

By absorbing water

How do the cortical granules expand the space between the cell membrane and vitelline envelope?

Increasing the electric potential of the egg.

Since the fertilization envelope is slow, what’s the sea urchin egg’s fast block to polyspermy?

Sperm cannot fuse to an egg with a positive electric potential.

Why does increasing the egg’s electric potential prevent polyspermy?

IP3

Which signaling molecule controls the release of Ca2+?

Stimulation of protein synthesis

What’s a function of Ca2+ beyond activating the release of cortical granules?

Capacitation

What is the term for the maturation of mammalian sperm?

Epithelial

Contact with __________ cells of the oviduct is required for sperm capacitation.

The change in electric potential

Which block to polyspermy occurs first-the change in the egg’s electric potential or the cortical granule reaction?

ZP2

What is the “mammalian version” of bindin?

Functional redundancy

ZP3 causes the acrosome reaction to occur in mammalian sperm, even though ZP2 allows the sperm to bind. Why do both of these chemicals exist in the same system?

No

Do mammalian eggs have a fast block to polyspermy, as seen in urchins?

It cleaves ZP2 and ZP3.

How does the cortical granule reaction differ in mammals from sea urchins?

Form a hardened shield

After the mammalian egg has been penetrated, it releases zinc ions. What do these do?

They undergo mitosis next to each other.

How do the pronuclei fuse together?