B6.2 - selective breeding/ generic engineering

Question 1

what is selective breeding

Answer 1

the breeding of species for favourable characteristics

Question 2

process of selective breeding

Answer 2

• decide which characteristic is desirable
• select parents with high levels of this characteristic
• breed from these individuals
• select the best offspring and breed again
• repeat for many generations

Question 3

risks of selective breeding

Answer 3

• inbreeding may reduce gene pool - lead to accumulation of harmful recessive characteristics- reduction in variation
• may be animal welfare issues eg breathing problems
• ## any useful alleles not found in desired organisms may be lost - smaller gene pool won’t contain variation to deal with environmental changes

Question 4

advantages of selective breeding

Answer 4

• sustainable food production is possible
• safe method of working as relies on natural processes and natural mutations
• selling produce that produces more meat/crops is profitable
• new varieties might be resistant to disease
• farmers and consumers can have desirable qualities

Question 5

plant selective breeding

Answer 5

• the male parts are removed to prevent self pollination
• once pollen has been transferred to flower an exclusion bag is placed over to avoid pollen reaching flower

Question 6

breeding plants to become disease resistant

Answer 6

• expose a population to a disease
• select those with resistance
• breed the resistant with each other and re expose to disease
• select those with resistance and repeat

Question 7

genetic modification

Answer 7

the movement of genes from one organism to another

Question 8

genetic engineering

Answer 8

when people selectively breed plants it’s slow
- altering an organisms genome to produce desired characteristics (faster and precise)

Question 9

genetic engineering involves

Answer 9

• taking genes from one species and introducing them into another
• these are foreign genes
• can be transferred as all organisms contain same basic genetic material

Question 10

genetic engineering process

Answer 10

• identifying gene that codes for a desired characteristic
• remove gene from donor organism
• insert the gene into the host organism (often bacterium)

Question 11

how to modify bacteria to produce insulin

Answer 11

• restriction enzyme cuts insulin gene from the human DNA
• a plasmid is removed from bacteria
• plasmid is cut open using same restriction enzyme
• human insulin gene and plasmid are mixed
• insulin is joined into the plasmid using DNA ligase enzymes
• plasmid carrying human gene is inserted into the new bacteria
• plasmid is called a vector (carries human gene)
• the bacteria is grown in large no. to produce insulin

Question 12

restriction enzymes

Answer 12

cut the donor dna at specific base sequences either side of the desired gene

Question 13

sticky ends

Answer 13

a staggered cut leaves exposed unpaired bases

Question 14

ligase enzyme

Answer 14

join donor DNA to host DNA at sticky ends

Question 15

plasmid

Answer 15

small circular dna found in prokaryotes

Question 16

vector

Answer 16

in genetic engineering a plasmid acts as a vector - used to transfer gene into an organism

Question 17

why use bacteria to produce insulin

Answer 17

to treat illnesses
- can make lots of insulin quick

Question 18

how scientists know foreign gene had been successfully transferred

Answer 18

• plasmid being used contains gene that codes for antibiotic resistance
• bacteria are transferred to an agar plate containing antibiotic and allowed to grow
• any bacterial colonies present must contain resistance marker gene - these also contain desired gene
• bacteria without plasmid die
• each bacterium with a plasmid makes a colony

Question 19

type of antibiotic used

Answer 19

kanamycin resistance
- rarely used in medicine so resistance to it won’t be a problem

Question 20

transgenic bacteria

Answer 20

have DNA from another organism

Question 21

why bacteria that don’t take up insulin gene die

Answer 21

the insulin gene contains resistance genes do without insulin gene it would die from antibiotic as doesn’t have resistance

Question 22

plant genetic modification

Answer 22

• plasmid removed and dna placed in it by restriction enzyme and ligase
• plasmid is a vector for the gene
• plant cells are infected with bacteria
• plant cells are screened with an antibiotic - any not taken up gene are killed
• cells grown into plantlets
• plants grown into a culture

Question 23

gmos

Answer 23

name for genetic engineering in plants

Question 24

golden rice modification

Answer 24

• produce beta carotene
• gene from daffodil
• body uses this to make vitamin A (deficiency leads to night blindness)

Question 25

herbicide resistant crops modification

Answer 25

• resistant to herbicide
• gene from plants with natural herbicide resistance
• increases crop yield as crop doesn’t die - can get rid of weeds easily

Question 26

Bt corn modification

Answer 26

• codes for protein that kills pest
• from soil bacterium
• don’t die as pests are killed
• crop yield increases

Question 27

safety concerns of genetic engineering

Answer 27

• religious teachings think it’s wrong to change natural organisms
• think it can cause cancer
• think herbicide still present in crop cells cause harm

Question 28

farmers cannot collect and sow seeds from gm crops why

Answer 28

will not breed true ( won’t have exact same characteristics) have to buy new seeds each season - seed companies exploit poor farmers

Question 29

why people might want to know if plants are genetically modified

Answer 29

• so seeds will breed true
• concerns of safety / ethics
• not want to eat/ buy

Question 30

embryo transplants - cloning

Answer 30

• cow is artificially inseminated with sorts from a bull with high dairy yield
• a developing embryo is removed from a pregnant female early so cells not yet specialised
• cells are separated and grown in culture and transplanted into host mothers (identical)
• in future it may be possible embryos may be genetically modified prior to implantation
• cows are clones