Development 1

Question 1

What is the first step of fertilization?

Answer 1

Capacitating: acidic environment of female reproductive tract open pores in enzyme-filled acrosome

*sperm receptors can detect chemicals released by egg: directional swimming

Question 2

What is the second step of fertilization?

Answer 2

Acrosomal Reaction: acrosome enzymes digest the outer membrane of the egg

Question 3

What is the third step of fertilization?

Answer 3

Fertilization: 1 sperm fuse with the plasma membrane of ovum, sperm head pass into cytoplasm

electrochemical rxn prevents egg permeability to other sperm

Question 4

What is the window of opportunity?

Answer 4

egg is fertile for 10-15 hours, sperm is fertile 48 hours

sex (copulation) must occur 48 hours before or 15 hours after ovulation

Question 5

How many egg(s)/sperm cell(s) are needed for identical/fraternal twins?

Answer 5

iden: 1 egg 1 sperm

frat twins: 2 egg 2 sperm

Question 6

IB: What is the cortical reaction?

Answer 6

during fertilization, vesicles near the egg membrane are activated

enzymes of the cortical granules digest binding proteins to prevent polyspermy