Nuclear Transfer & Cloning

Question 1

What are the 2 ways nuclear transfer can occur ?

Answer 1

1. Removal of nucleus & injection into new cell
2. Fusion of 2 cells with an electric current

Question 2

What is cloning limited by ?

Answer 2

• number of nuclei that can be harvested
• number of oocytes available to receive nuclear transfer

Question 3

Briefly describe reproductive cloning

Answer 3

• Oocyte nucleus removed
• replaced by nucleus from adult cell
• cells grow & multiply like an embryo
• animal produced is a genetic copy of animal nucleus came from

Question 4

What’s a famous example of reproductive cloning ?

Answer 4

Dolly the sheep

Question 5

Describe therapeutic cloning

Answer 5

-nucleus of somatic cell is transferred to oocyte but embryo is never implanted & no animal is produced

Question 6

What are some pros of therapeutic cloning ?

Answer 6

• production of interesting cell lines & stem cells
• drug testing

Question 7

What is SCNT ?

Answer 7

Somatic cell nuclear transfer

Question 8

What does nuclear transfer involve ?

Answer 8

• oocyte maturation,
•cell cycle synchronization of donor cells,
•enucleation,
•cell fusion,
•oocyte activation and
•embryo culture.

Question 9

What 2 things determine the proportion of oocytes developing into blastocytes ?

Answer 9

1. Recipient cytoplasm
2. Nuclear donor

Question 10

What happens to the eggs nucleus during oocyte maturation ?

Answer 10

• Eggs nucleus = germinal vesicle
• GV has broken down prior to ovulation
• so egg is enucleated

Question 11

When & How are chromosomes removed ?

Answer 11

• metaphase chromosomes
• removed by aspiration

Question 12

How in enucleatipn enhanced ?

Answer 12

By labelling the oocyte DNA with nuclear fluorescent dyes, such as Hoechst 33342.

Question 13

Oocyte activation can be instigated by exogenous stimulation such as?

Answer 13

Electrical,
•Chemical,
•Mechanical,
•and very rarely spontaneous activation can happen