recombinant DNA technology exam questions

Question 1

suggest why the polasmids were injected into the eggs of silkworms rather than the silk worms (2)

Answer 1

-gene gets into all cells of silkworms
-so gets into cells that make silk

Question 2

suggest why the scientist used a market gene and why they used the EGFP gene (2)

Answer 2

-not all cells will take up gene
-silkworms that have taken up gene will glow

Question 3

suggest 2 reasons why it was important that the sipider gene was expressed only in the silk glands of the silkworm (2)

Answer 3

so protein can be harvested
fibres in other cells might cause harm.

Question 4

explain why primer A3 and primer A4 only bind to specific DNA fragments

Answer 4

-specific base sequence
-which is complimentary

Question 5

the scientist wanted to kjnow on which chromosome the gene will alleles r and r was located. From the flies with genotype RR, they obtaianed cells that were in mitosis and added a labelled DNA probe specific for allele R. They then looked at the cells under an optical microscope.
Explain why they usesd cells that were in mitosis (2)

Answer 5

-chromosomes visible

-can see which chromosomes DNA probe attached to.

Question 6

the scientists concluded that the resistance of the flies the insectide is partly due to incerased activity of PM but other factors are also involved.
Explain how these data support this conclusion (4)

Question 7

the desired gene in the diagram was from an insect., In stage 6 the plant containing the gene was able to use it to synthesise an insect protein.
the plaant is able to synthesise the insect protein

explain why this is possible

Answer 7

genetic code is universal
DNA of insect is transcribed
can be translated.

Question 8

explain why this DNA probe will only detect allele A

Answer 8

probe is complimentary to allele A and binds by forming hydrogen bonds
gives out green light.

Question 9

explain the curve for person H

Answer 9

more probe binds
DNA doubles each cycle
so light doubles.

Question 10

the rats were not fed for ta least 6 hours before their blood gluc0ose concentration was measured. Explain why (1)

Answer 10

glucose would affect the results

Question 11

research workers have suggested that treating diabetes in humans by this ethod of gene therapy would be better than injecting insulin. Evaluate this suggestion (4)

Answer 11

avoids injections
longer term treatment
less restricted diet
rats are different to humans
long term side effects not know

Question 12

the jellyfish gene attach3ed to teh humanf actor IX gene codes for a proteint aht gllows green under flurescent light. Explain the purpose of attaching this gene. (2)

Answer 12

-acts as a marker gene- shows that jellfish gene has been taken up by cells.
-only embryos which show fluorescence have taken up gene.

Question 13

the promoter DNA from sheep causes transcript0n of genes coding for proteins fouond in sheep milk,
Suggest the advantage of using this promoter DNA.
(2)

Answer 13

-gene only expressed in mammory glands
-do not need to kill sheep

Question 14

use your knowledge of enzymes to explain why restriction enzymes only cut the DNA at specific sites (2)

Answer 14

-different lengths of DNA have differnet base sequences
-results in different shape

Question 15

what is the role of a vector?

Answer 15

carries genes into a cell

Question 16

describe the role of restirciton endonucleases in the formation of plasmids that contain donor dna (3)

Answer 16

cut open plasmid
cut donor DNA and plasmid with same enzyme
that cut at same DNA base sequence

Question 17

the gene was injected into isoalted cells of the crop plant.
these cells were then cloned and new plants grown from the cloned cells
explain the advantage of inserting the gene into isolated plant cells rather than direclty into cells within a whole plant (3)

Answer 17

-isolated cells divide by mitosis
-to produce many plants
-all cells in plant produce toxin

Question 18

explain how the use of a gene probe could enable the presence of a mutant allele of the cystic fibrosis gene to be detected (4)

Answer 18

DNA probe will attach
to one DNA strand
due to complimentary base pairing
-radioactivity detected on film

Question 19

Sheep have been genetically engineered to produce alpha-1-antitrypsin which is used to treat cystic fibrosis. Use your knowledge of this process to explain one argument for and one against using sheep in this way (2)

Answer 19

can produce large quantities
against- long term effects not known

Question 20

what is meant by gene therapy?

Answer 20

introducing a healthy gene

Question 21

) The ADA gene is inserted into a virus. Give two advantages of using a virus in gene therapy (2)

Answer 21

-can carry gene into cell
-can be replicated

Question 22

ndividuals who have been treated by this method of gene therapy do not pass on the ADA gene to their children. Explain why. (1)

Answer 22

gene is not in gametes

Question 23

Explain why treatment of ADA deficiency by gene therapy must be repeated at regular intervals, whereas a single bone marrow transplant can provide a permanent cure.

Answer 23

t lymphcytes don’t reproduce
bone marrow provide continuous supply

Question 24

what is the role of a primer?

Answer 24

enables replication to start

Question 25

Give two ways in which the polymerase chain reaction differs from the process of transcription.

Answer 25

-uses RNA polymerase
-uses RNA nucleotides- uracil

Question 26

Whole potato plants can be produced from genetically identical potato cells grown in a tissue culture. Use your knowledge of genes to suggest how different cells, such as leaf and root cells, can develop from genetically identical cells. (2)

Answer 26

differnet genes expressed
producing different proteins