Gene Technology

Question 1

Artificial selection

Answer 1

Humans choose which characteristics (and alleles) will be passed onto the offspring

Question 2

Selective breeding

Answer 2

• The desired characteristics are identified
• Individuals with them are bred together
• Only the offspring exhibiting the desired characteristics are chosen and bread together again
• This is repeated over several generations until the desired trait is fully developed

Question 3

Advantages of selective breeding in animals

Answer 3

• Undesirable characteristics can be removed from the genotype of a breed
• Desirable characteristics can be chosen
• Higher yields mean more profit

Question 4

Disadvantages of selective breeding in animals

Answer 4

• Animal welfare issues
• Takes a long time (many generations)
• Not always reliable
• If a population is genetically similar, they are vulnerable to pathogens

Question 5

Selectively bread plants advantages

Answer 5

• grow quicker
• higher yield
• more resistant to disease

Question 6

Natural selection vs selective breeding

Answer 6

• Selective breeding is artificially done by humans choosing who breeds, rather than it being those with beneficial alleles
• Natural selection is slower (millions of years)

Question 7

Transgenic

Answer 7

The transfer of genetic material from one species to another

Question 8

Genetic engineering

Answer 8

• The artificial multiplication of the genetic material in a living organism
• Produces an organism with a unique set of genes
  (Not the same as cloning)

Question 9

Transgenic organism

Answer 9

An organism that has been engineered with genes inserted from a different species

Question 10

Benefits of genetic modification of plants

Answer 10

• Food crops can be grown in countries where they normally wouldn’t
• Food is cheaper/ more economically viable
• Faster than selective breeding

Question 11

Recombinant DNA

Answer 11

Making a new combination of DNA bases, by combining DNA from two species

Question 12

Plasmid

Answer 12

Small, circular pieces of DNA

Question 13

Restriction enzymes

Answer 13

Enzymes that cut DNA molecules at specific places

Question 14

DNA ligase

Answer 14

Enzymes that join the cut ends of DNA molecules

Question 15

Vector

Answer 15

Used to transfer genes

Question 16

Making a GMO

Answer 16

• extract DNA from cell
• restriction enzymes cut the specific gene out of the DNA, and plasmid from bacteria DNA
• ligase enzymes stick the gene into the bacteria plasmid
• the plasmid with the gene is put into the bacteria
• the bacteria reproduce

Question 17

Plasmids and viruses as vectors

Answer 17

Insert recombinant DNA into other cells

Question 18

GM plants eg

Answer 18

To increase food production:
- insect resistant
- herbicide resistant

Question 19

In vitro

Answer 19

Outside a living organism

Question 20

How to micropropgate plants

Answer 20

• a plant with desirable characteristics is selected
• An explant is taken from this parent plant
• explants are sterilised (with disinfectant) to remove pathogens and bacteria that could compete for resources, eg. minerals
• These are transferred to a sterile petri dish, containing sterile nutrient agar
• explants grow and divide into a small plant/callus (masses of cells)
• each plant is transferred to a fresh growth medium, containing plant hormones
• a plantlet that is genetically identical to the original plant is formed

Question 21

Advantages of micropropagation

Answer 21

• large numbers of genetically identical plants can be produced rapidly
• can be used for species that are hard to grow from seeds
• plants can be produced at any time of year
• large numbers of plants can be stored easily
• genetic modifications can be introduced into many plants quickly, after modifying only a few

Question 22

Disadvantages of micropropogation

Answer 22

• susceptible to diseases
• costly

Question 23

Cloning a mammal

Answer 23

• nucleus of an egg cell from sheep 1 is removed, creating an enucleated cell
• A diploid nucleus, from a cell of sheep 2, is inserted in its place
• cell is stimulated with an electric shock
• nucleus fuses with empty egg and divides by mitosis to form an embryo
• the cloned embryo is implanted into the uterus of sheep 3
• the lamb born is a cline of sheep 2

Question 24

How can cloned transgenic animals produce human proteins

Answer 24

By transferring human genes into animal cells, eg. Cows/sheep can produces useful human proteins in their milk

Question 25

Stem cell

Answer 25

The cell that has the ability to divide many times by mitosis, without changing. They can later differentiate into specialised cells.

Question 26

Two main types of stem cells in humans

Answer 26

- In the early stage of development of the embryo - In adult tissues, eg. Bone marrow, skin, intestine lining

Question 27

Importance of specialised cells

Answer 27

- Can carry out particular functions - Especially important in the formation of tissue (groups of similar specialised cells, carrying out a particular function

Question 28

Why are stem cells important in embryos

Answer 28

They are the source of all specialised cells in the development of an individual

Question 29

Disadvantages of stem cells in medicine

Answer 29

- ethical issues - Some people feel that using embrace in this way undermines our respect for human life