Topic 8: exam qs

Question 1

Recombinant DNA technology can involve the transfer of fragments of human DNA
into bacteria. The bacteria are then used to produce human proteins.

Give two reasons why bacteria are able to use human DNA to produce human
proteins.
[2 marks]

Answer 1

1. (The) genetic/DNA code is universal
   OR
   The same triplets/codons code for the same
   amino acids (in all species);
2. (The mechanism of) transcription is
   universal;
3. (The mechanism of) translation is universal;

Question 2

Suggest and explain one reason why bacteria might not be able to produce every
human protein.
[1 mark]

Answer 2

Cannot splice (pre-mRNA), so cannot remove
introns
OR
Do not have Golgi (apparatus), so cannot
process/modify (proteins)
OR
Do not have transcriptional factors (required), so
cannot carry out transcription/produce mRNA;

Question 3

Explain the purpose of the marker gene.
[1 mark]

Answer 3

Shows that the (antithrombin) gene has been
taken up (by cells/embryos/goats)
OR
Shows transgenic/transformed goat cells/goat
embryos/goats
OR
Allows detection of genetically modified cells/
organisms/mammals/goats;

Question 4

The enhancer only stimulates region M in the milk-producing glands of a goat.
Suggest two explanations for the importance of the enhancer being included in the
DNA fragment transferred.
[2 marks]

Answer 4

1. Milk/protein/antithrombin is easy to extract
   from a goat
   OR
   Extracting milk/protein/antithrombin from a
   goat does it no harm;
2. If (antithrombin was produced) in their blood,
   could prevent/affect clotting
   OR
   (Antithrombin) could damage other cells;