Cellular Development and Differentiation

Question 1

What is the male gamete?

Answer 1

Sperm cell (spermatozoan)

Question 2

What is the female gamete?

Answer 2

Egg cell (ovum)

Question 3

Where does fertilisation in humans occur?

Answer 3

In the ampulla of the uterine tube

Question 4

What is the term that refers to the fusion of sperm and egg?

Answer 4

Syngomy

Question 5

State the steps of blastocyst formation

Answer 5

1) One cell is fertilised
2) Cell undergoes cleavage to form 2 blastomeres
3) Division forms a morula (ball of cells) which enters the uterine cavity
4) Cavity in the morula (blastocoel) forms to give a blastocyst

Question 6

What is the trophoblast of the blastocyst?

Answer 6

The layer of cells on the outside containing the blastocoel

Question 7

What is the embryoblast/inner cell mass of the blastocyst?

Answer 7

Bundle of cells inside

Question 8

What are the 3 parts of the blastocyst and what do they all produce?

Answer 8

Trophoblast - produces the placenta
Embryoblast - produces the offspring
Blastocoel - cavity in embryo

Question 9

The inner cell mass is opposite what?

Answer 9

The sperm entry

Question 10

What does the blastocyst undergo?

Answer 10

Gastrulation

Question 11

What are the 3 germ layers?

Answer 11

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 12

What are the four basic tissues?

Answer 12

• Muscle
• Connective
• Nervous
• Epithelial

Question 13

Which germ layers produce which basic tissue?

Answer 13

• Ectoderm; epithelial
• Mesoderm; muscle, connective, epithelial
• Endoderm; nervous, epithelial

Question 14

What 2 types of growth increase tissue volume in the developing embryo? What do each of them involve?

Answer 14

Hyperplasia - increase in cell number

Hypertrophy - increase in cell volume

Question 15

Define differentiation

Answer 15

Unequal but controlled change in structure resulting in a functionally different area

Question 16

What is meant if a cell is totipotent?

Answer 16

It can differentiate to form any type of cell in the body

Question 17

What is the basis of differentiation in a developing embryo?

Answer 17

All cells contain ALL genes but will only express specific genes resulting in differentiation

Question 18

Is differentiation reversible?

Answer 18

No, each ‘choice’ is unidirectional and irreversible

Question 19

Stem cells in adults are determined, what does this mean?

Answer 19

They are committed to a particular developmental pathway

Question 20

What is meant if a cell is unipotent?

Answer 20

It can only differentiate into 1 type of cell

Question 21

What is meant if a cell is pluripotent?

Answer 21

It can differentiate into several types of cells

Question 22

Other than selective gene activation, what other factors can influence gene activity?

Answer 22

Epigenetic influences

- Morphogens can result in gene activation in cells

Question 23

What is terminal differentiation?

Answer 23

When a cell fully differentiates into one of the highly specialised cell types in the body
(following one path cuts out others until only one endpoint is left)

Question 24

What can abnormalities in growth and differentiation cause in individuals?

Answer 24

• Cancer

- Deformities