Fertilization, Implantation and Gastrulation Weeks 1-3

Question 1

The zona contains sperm receptors that recognize what?

Answer 1

integral proteins of sperm plasmalemma

Question 2

What is the function of the Zona (Cortical) Reaction?

Answer 2

prevention of polyspermy

Question 3

3 phases of fertilization are_____

Answer 3

1 penetration of corona radiata
Sperm binding (SED1 Protein) and penetration of zona
Acrosome reaction - lysis by enzymes

Question 4

What happens in the fast component of the cortical reaction?

Answer 4

change in the resting potential of oocyte plasma membrane prevents further sperm binding

Question 5

What happens in the slow component of the cortical reaction?

Answer 5

cortical granules are released that destroy sperm receptors (ZP3)

Question 6

What does Izumo do?

Answer 6

it is required for the fusion of sperm to egg

Question 7

What is mosaicism?

Answer 7

Cells within one individual have a different genetic make up. Some cells have a normal number of chromosomes others do not.

Question 8

Somatic mosaicism

Answer 8

mitotic non-dysjunction eary in cellular division

Question 9

Examples of gonadal or tissue mosaicism

Answer 9

Mosaic Down syndrome
Segmental neurofibromatosis (NF1)
McCune-Albright Syndrome: GNAS1 mutations

Question 10

Difference between Mosaicism and Chimerism

Answer 10

Mosaic= genetically different cells, same zygote.

Chimera - genetically different cells, different zygotes. (Like Fraternal twins becoming one individual).

Question 11

Blaschko’s lines are evidence of

Answer 11

genetic mosaicism

Question 12

Barr bodies are formed through what process

Answer 12

Lyonization

Question 13

What is lyonization?

Answer 13

When one X chromosome is functionally inactivated

Question 14

About how long does nuclear fusion take?

Answer 14

12 hours

Question 15

The fusion of pronuclei begins what process?

Answer 15

embryogenesis

Question 16

Cleavage is

Answer 16

a series of mitotic divisions

Question 17

What is the name of the embryo after it has divided several times, but is still enclosed within the zona pellucida?

Answer 17

Morula

Question 18

What is a defining characteristic of a Blastocyst?

Answer 18

a blastocoele

Question 19

What happens to the Zona Pellucida after the blastocyst forms?

Answer 19

It begins to dissipate, and the blastocyst hatches out of it

Question 20

What are the cells called that form the outer cell mass?

Answer 20

Trophoblast

Question 21

What does the embryoblast become?

Answer 21

the embryo

Question 22

What does the trophoblast help form?

Answer 22

the placenta

Question 23

Define Totipotent

Answer 23

can grow into an entire organism, and even produce extra embryonic tissues

Question 24

Define pluripotent

Answer 24

stem cells that cannot grow into a whole organism, but can differentiate into cells derived from any of the three germ layers