2. You are working on in a molecular genetics lab on a new mutagen found in terr

Question

2. You are working on in a molecular genetics lab on a new mutagen found in terrapin skin. You use it
to induce mutations in test bacteria and sequence the mutant proteins produced by the mutant genes.
Several of these are clustered near the amino terminal region of the protein and these are shown below.
For this question assume all of the mutations are due to single base pair changes.
wild type gene ...AUG AAA GGG GGC GGT CAT TTT GGA TTT TTT GCA GGT CCT TGG....
protein                Met   lys gly gly gly his phe gly p he phe ala gly pro trp..
residue               1         2     3    4     5   6    7    8   9   10   11 12   13   14

You find the following changes in different mutants:
lys 2 to thr
his 6 to pro
phe 9 to cys
trp 14 to gly
The data provides evidence that the mutagen can cause which
of the following base changes:
A. A to T
B. G to C
C. A to C
D. T to A
E. all of the above are possible
3. Compared to a typical human gene.
A. A typical Drosophila gene will be the same size.
B. A typical yeast gene will have the same number of introns.
C. A typical E. coli gene will be the same size.
D. A typical Drosophila gene will be larger.
E. none of the above are correct.
4. Which of the following are true about DNA transposable elements
A. They contain long terminal repeats (LTR).
B. To transpose they must also replicate.
C. The insertion of a DNA transposon results in a small duplication (e.g. 8 bp) of host chromosome
sequences.
D. They encode a GAG protein.
E. The Ty element of yeast is a member of this class of transposable elements.

Explanation / Answer

The data provides evidence that the mutagen can cause A to C change.

lysine2 to threonine means, AAG TO ACG

Histidine6 to proline means CAC to CCC

This clearly indicates change of A to C.

3.A typical Drosophila gene will be larger.

4. They contain long terminal repeats (LTR).

The insertion of a DNA transposon results in a small duplication (e.g. 8 bp) of host chromosome
sequences.

both are true

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