cloning

Question 1

what is micropropagation

Answer 1

a method of cloning plants by growing small pieces of plant tissue (called explants) in sterile conditions on a nutrient medium to produce genetically identical plants.

Question 2

steps of micropropagation

Answer 2

1- explants (small pieces of a plant) are taken from parent plant

2- they are sterilised to kill any microorganisms

3- explants are placed in sterile nutrient agar in a petri dish ( in vito= out of the body)

4- cells divide and form s callus (mass of identical cells)

5- callus is transferred to a new growth medium with plant growth hormones

6- plantlets planted in soil to grow into fully developed plants

Question 3

why use micropropagation (2)

Answer 3

produces many clones quickly

useful for rare, endangered species or genetically modified plants

Question 4

advantages of micropropagation (commercial) (5)

Answer 4

• can be grown all year round
• produces clones with desirable traits
• large numbers of plants produced cheaply
• useful in producing disease resitant plants
• helps conserve areas and endangered plants

Question 5

disadvantages of micropropagation (commercial) (3)

Answer 5

• requires sterile lad conditions and expert staff
• all clones genetically equal so vulnerable to same diseases and pests
• no genetic variation so no adaptation to changes

Question 6

embryo cloning

Answer 6

A fertilised egg (zygote) is created using sperm and egg from desired animals.

The embryo is allowed to divide a few times by mitosis (usually at the 8-cell stage).

The cells are separated and grown in a lab — each cell can become a full embryo.

These embryos are implanted into different surrogate mothers.

All offspring are genetically identical

Question 7

adult cell cloning

Answer 7

• nucleus is removed from an unfertilised egg cell
• nucleus from adult body cells is inserted into the egg
• a tiny electric shock stimulates the egg to divide by mitosis to form an embryo
• these embryo cells contain the same genetic information as adult cell
• when the embryo has developed into a ball of cells, it’s inserted into a host mother to continue the development until birth

Question 8

benefits of cloning (3)

Answer 8

• can be used to preserve endangered species and resurect extinct animals
• quick and cheap for commercial production and high quality products all year (plants)
• allows farmers to increase yields by using high quality livestock and plants

Question 9

risks of cloning (3)

Answer 9

• lack of genetic diversity
• some evidence that cloned animals may be less healthy than normal ones
• ethical concerns

Question 10

cloning to produce human proteins

Answer 10

The gene for the desired human protein (e.g. insulin) is identified.

A restriction enzyme cuts the gene out of human DNA.

The same enzyme is used to cut open a bacterial plasmid (loop of DNA).

The human gene is inserted into the plasmid using DNA ligase → this forms recombinant DNA.

The recombinant plasmid is inserted into a bacterial cell.

The bacterium divides by binary fission, copying the human gene each time.

The bacteria produce the human protein as they grow.

The protein is collected and purified for use in medicine.

• PROCESS CALLED PHARMING

Question 11

example of cloning to produce human proteins

Answer 11

antibodies for cancer treatment