Manipulating genomes

Question 1

Electrophoresis

Answer 1

the DNA is placed at the cathode and due to its negative charge it will travel through the agrose gel to the anode. The smaller fragments of DNA will travel faster and the DNA will be seperated in size order - make sure it is timed. A dye is then added to the buffer solution and the complimentary sequence of DNA can be read

Resolution on gel sufficient to one nucleotide base

Question 2

How does the diameter of the bronchioles become reduced

Answer 2

Extra mucous production
Inflammation
Restricts air flow

Question 3

PCR

Answer 3

Amplifies a short piece of DNA which produces a range of DNA at different lengths

Question 4

DNA restriction enzymes

Answer 4

To cut plasmids / vectors
To cut (genome DNA) into smaller fragments

Question 5

Why does the genome need to be fragmented before sequencing

Answer 5

Genome to large

Accuracy better with smaller fragments

Divide job over time

Question 6

How would a plant with polyploidy appear

Answer 6

Larger in size

Question 7

How does the phylogenetic approach to classifying species differ from the biological species concept

Answer 7

No need to test for interbreeding
Can apply to organisms that reproduce asexually
Can apply to extinct organisms
Common ancestor

Question 8

Enzyme that cuts DNA

Answer 8

Restriction endonuclease

Question 9

A vector to introduce foreign DNA into bacteria

Answer 9

Plasmid
BAC
Bacteriophage

Question 10

A vector to introduce foreign DNA into plant cells

Answer 10

Plasmid
Virus
Agrobacterium tumefaciens

Question 11

A vector to introduce foreign DNA into animal cells

Answer 11

Plasmid

Question 12

Recombinant DNA

Answer 12

DNA molecule treated in vitro by joining DNA with a vector molecule of DNA

Question 13

DNA Polymerase

Answer 13

catalyses formation of double stranded DNA from a single stranded DNA template

Question 14

DNA Ligase

Answer 14

catalayses formation of phosphodiester bonds between sugar and phosphate groups of DNA backbone strands

Question 15

Assess the potential danger to natural habitats of cultivating transgenic crops

Answer 15

For example, the study/trial shows that these are not likely to survive if they escape into the wild; most extinct within four years; all population sizes shrunk within first year; some people fear that genes for herbicide resistance could transfer to weeds; probably unlikely as genes do not normally transfer from crop plants to wild weed plants; they are different species so cross pollination not likely/pollen not compatible; even if hybrids were produced, they are likely to be infertile (contrast this with garden escapes, such as rhododendron or Japanese knotweed that are invasive and destructive)

Question 16

Ethical implications of growing GM crops

Answer 16

For example, need to produce more food to meet demands of growing population; cannot just keep using more fertiliser and pesticides; need to make crops resistant to drought/flood/higher temperatures; as well as to diseases/pests; also need nutritionally enhanced crops; suitable examples, such as Golden RiceTM, bananas with more zinc; pesticide resistance could eliminate need for pesticides and exposure of sprayers to the pesticides; concerns about effects of GM crops on biodiversity; but they have been grown in US for 20 years and no apparent loss of biodiversity; no obvious ill health consequences to humans from eating them have been seen so far; suggestions GM causes reduction in honey bee populations; but this unlikely to be the case as bee populations are dwindling in UK and no commercially grown GM here; more likely to be (nicotinoid) pesticides; accept all valid points in balanced argument.

Question 17

How are viruses used as vectors in gene therapy

Answer 17

Virus genes/genome knocked out or altered; so not virulent/cannot cause infection; insert gene to be delivered within the protein coat of virus; can be injected or breathed in in vivo; can be injected into extracted cells in vitro and then altered cells placed back into patient; viruses dock with receptors on host cell plasma membranes and enter the cell, so can carry in the gene; many viruses insert their genes into host genome.

Question 18

Why does treatment for cystic fibrosis need to be repeated

Answer 18

Treatment for cystic fibrosis needs to be repeated as epithelial cells lining the airways are replaced every 10-14 days; therefore new cells will need to the genes to be inserted