Cloning

Question 1

What is a clone?

Answer 1

An individual that is genetically but not necessarily phenotypically identical to another individual

Question 2

What are the different mechanisms of cloning?

Answer 2

Natural

Embryo splitting

Reprogramming somatic cells

Nuclear transfer

Question 3

What are the two types of natural cloning?

Answer 3

Asexual reproduction e.g. hydra bud in spring and summer when conditions are good

Monozygotic twins

Question 4

What is an example of embryo splitting?

Answer 4

Spemann experiment

Question 5

How do we reprogram somatic cells in plants?

Answer 5

Treat cells from original plant and treat with growth factor

Grows into a new plant that is genetically identical

Question 6

What features allow somatic cell nuclear transfer?

Answer 6

Nucleus of every somatic cell contains a complete copy of individual’s genome

Fertilised egg is totipotent

Question 7

How is somatic cell nuclear transfer carried out?

Answer 7

DNA from one cell is combined with an enucleated fertilised egg

Question 8

Why is somatic cell nuclear transfer controversial?

Answer 8

Technique is invasive

There are technical problems

Gives rise to ethical dilemmas

Question 9

How was Megan and Morag created?

Answer 9

Sheep embryo arrested in Go by depriving them of growth factor

Took DNA and transferred into enucleated egg and stimulated to develop

Early embryos placed into uterus of surrogate

Megan and Morag born

Cloned from cultured differentiated embryo cells

Question 10

How was Dolly created?

Answer 10

Cloned from adult cell

Took cells from adult sheep mammary gland

Arrested in their development

Cells then fused with enucleated eggs (also from adult)

Stimulated them and transplanted into surrogate

Dolly was born

Question 11

What was Polly?

Answer 11

First transgenic mammal clone

Question 12

What did Polly’s milk contain?

Answer 12

Human factor IX - treats haemophilia

Question 13

What are the misunderstandings with cloning?

Answer 13

Clones will not bring back a loved one

Clones are only DNA clones (not cytoplasmic)

Have own mutations

Environment is important

Question 14

What are some problems with cloning?

Answer 14

Clone has parent telomere so have shorter ones - die earlier

Large foetus syndrome and prolonged gestation

Low success rate (1/277 transnucleated cells for Dolly)

Lack of genetic variation may lead to disease vulnerability

Human cloning may cause psychological problems

Foetus is 10x more likely to die in utero and 3x more likely to die at birth

Question 15

What are some potential cloning uses?

Answer 15

Developmental research - using clones as controls

Conservation

Cloning elite livestock

Disease resistant farming

Assisted reproductive techniques

Therapeutic cloning

Pharming

Xenotransplantation

Question 16

What happens when you give stem cells vitamin A derivatives?

Answer 16

Form nerve cells

Question 17

How are stem cells used in medicine?

Answer 17

Epidermal nucleus of patient put in enucleated cells

Inner mass divided into clumps to produce colonies

Treat colonies with specific differentiated factors

Can help overcome transplant rejection as cells are from original patient

Question 18

What are the problems with using stem cells in medicine?

Answer 18

Need cells from an embryo then need to discard embryo

Trying to get stem cells from bone marrow

Question 19

What are some examples of conservation cloning?

Answer 19

Cloning rare breeds:
Banteng - did not survive to adulthood
Mouflon - did survive

Cloning extinct species:
Pyrenean ibex - only species to have been brought back but only lived 7 minutes