Question

1)This stretch of DNA includes the beginning of the protein-coding region of a gene. The lower strand is the template strand.

5’...T A A T G A G T G T T G T T A G T ...3’ .   

3’...A T T A C T C A C A A C A A T C A ...5’ ← template strand

What is the corresponding mRNA that would be created from this portion of the gene?

2) This stretch of DNA includes the beginning of the protein-coding region of a gene. The lower strand is the template strand.

5’...T A A T G A G T G T T G T T A G T ...3’ .   

3’...A T T A C T C A C A A C A A T C A ...5’ ← template strand

Write out the amino acid sequence for the gene segment using the codon table. MAKE SURE to locate correct place in the mRNA where polypeptide assembly begins.

3) If there was a substitution at the 14th nucleotide and the DNA sequence is now:        

5’...T A A T G A G T G T T G T G A G T ...3’

3’...A T T A C T C A C A A C A C T C A ...5’

What kind of mutation is this?

4)If there was an insertion mutation at the 12th nucleotide and the DNA sequence is now:

5’...T A A T G A G T G T T G T T T A G T ...3’

3’...A T T A C T C A C A A C A A A T C A ...5’

What kind of mutation is this?

Answer 1

1.The sequence of mRNA is :

5' U A A U G A G U G U U G U U A G U 3'

2. The polypeptide synthesis will start from the AUG codon. Thus, the polypeptide sequence from the above mRNA would be :

Met-Ser-Val-Val-Ser

3. This is an example of point mutation, where a transition is taking place , A to G and T to C.

4. This is an example of insertion mutation, which will cause a frameshift in the coding sequence of the mRNA, thus resulting in a change in the polypeptide sequence.