gene technology

Question 1

the desired gene in the diagram was from an insect

In stage 6, the plant containing this gene was able to use it to synthesise an insect protein

Answer 1

• the genetic code is universal
• therefore it can be transcribed and translated to produce the protein
• the machinery for this is the same in all organisms

Question 2

explain why some of the plants contained the desired gene and some of their cells and others did not

Answer 2

• the plants that had the plasmid DNA in their nucleus meant that they could replicate the DNA within the nucleus
• when the cell undergoes mitosis, all their cells would contain the desired gene
• this produces genetically identical DNA

Question 3

explain why the scientists used the same restrictive endonuclease on each DNA sample

Answer 3

so to cut the fragments at the same piece in order to get the same gene

Question 4

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

Answer 4

each has specific base sequences

that is complementary to allele r or R

Question 5

explain why they used cells that were in mitosis

Answer 5

the chromosomes only become visible during mitosis

so we can see which chromosome the DNA probe is attached to

Question 6

explain the curve for person H (look at the exam booklet)

Answer 6

• more probes binding
• DNA with A doubles each PCR cycle
• so light approximately doubles in intensity

Question 7

suggests and explains how delayed insertion of the GH gene could produce offspring of transgenic fish without desired characteristic

Answer 7

the GH gene is inserted into the nucleus once it had already been replicated

therefore cells producing the gametes do not receive the gene

Question 8

name two techniques the scientists may have used when analysing viral DNA to determine that the viruses were closely related

Answer 8

1. genetic fingerprinting

2. genome sequencing

Question 9

determining the genome of the viruses could allow scientists to develop a vaccine

Explain how

Answer 9

the scientists could identify the proteome

therefore the scientists can identify antigens that can be used to develop vaccines

Question 10

what is a DNA probe

Answer 10

it is a short single strand of DNA

its bases are complementary with a section of DNA/an allele/ gene

Question 11

describe how restriction endonuclease work

Answer 11

restriction endonuclease cuts DNA at specific base sequences

Question 12

explain why only using the gene machine and reverse transcriptase was used to produce DNA that E.coli could use to make HGH

Answer 12

human DNA contains introns/ method 2 and 3 produces DNA without introns

E.coli can not remove introns

Question 13

describe how the geneticist would attempt to insert copies of the HGH gene into these plasmids

Answer 13

1. Cut the plasmid with a restriction endonuclease;

Allow ‘add base sequences to blunt ends of plasmid and HGH gene’

2. (So that) both have complementary / sticky ends;
3. (Mix together) and add ligase to join the complementary / sticky ends;

Question 14

describe the role of reverse transcriptase

Answer 14

produces DNA using mRNA

Question 15

explain the role of DNA polymerase

Answer 15

joins nucleotides to produce complementary strands of DNA

Question 16

describe genetic fingerprinting

Answer 16

1.DNA is cut;
2.using restriction enzyme;
3.electrophoresis;
4.separates according to length / mass / size
;5.DNA made single-stranded;6.transfer to membrane / Southern blotting;
7.apply probe;
8.radioactive / single stranded / detected on film / fluorescent;
9.reference to tandem repeats / VNTRs / minisatellites;
10.pattern unique toevery individual;

Question 17

suggest why a DNA probe for the mutated triplet was not considered a suitable method for detection of the E280A

Answer 17

GCA is found in other places

so would not know if it was the mutation