) A fragment of a wild-type polypeptide is sequenced for seven amino acids. The

Question

) A fragment of a wild-type polypeptide is sequenced for seven amino acids. The same polypeptide region is sequenced in four mutants.

Wild-type

N … Thr – His – Ser – Gly – Leu – Lys – Ala …C

Mutant 1

N … Thr – His – Ser – Val – Leu – Lys – Ala …C

Mutant 2

N … Thr – His – Ser …C

Mutant 3

N … Thr – Thr – Leu – Asp …C

Mutant 4

N … Thr – Gln – Leu – Trp – Ile – Glu – Gly …C

a) Use the available information to characterize each mutant in detail. Explain you answer.

b) Determine all possible wild-type mRNA sequences that fit with all the mutants listed above.

c) Identify and describe the mutation that produces each mutant polypeptide. Pick a wild-type sequence and write the corresponding mRNA sequence for each mutant, show the translation of that sequences, and clearly mark the mutation.

Wild-type

N … Thr – His – Ser – Gly – Leu – Lys – Ala …C

Mutant 1

N … Thr – His – Ser – Val – Leu – Lys – Ala …C

Mutant 2

N … Thr – His – Ser …C

Mutant 3

N … Thr – Thr – Leu – Asp …C

Mutant 4

N … Thr – Gln – Leu – Trp – Ile – Glu – Gly …C

Explanation / Answer

A) mutant 1 - here , there is a change in one nucleotide, i.e. The G residues in the glycine amino acid is converted to U residue resulting the conversion of glycine residues to valine residues, i.e. Resulting in a Transition mutation/ misses even mutation coding for a different amino acids

Wild-type N … Thr – His – Ser – Gly – Leu – Lys – Ala …C

Mutant 1 N … Thr – His – Ser – Val – Leu – Lys – Ala …C

Mutant 2 - deletion

Wild-type N … Thr – His – Ser – Gly – Leu – Lys – Ala …C

Mutant 2 - N … Thr – His – Ser …C

Mutant 3 ) Deletion of the end sequences

Mutant 4) insertion of a new sequence between thre and gln, resulting in a complete new sequence.

B and C

Wild type -

Mutant 1

Mutant 2

Mutant 3

Mutant 4

Wild-type N … Thr – His – Ser – Gly – Leu – Lys – Ala …C

Mutant 1 N … Thr – His – Ser – Val – Leu – Lys – Ala …C

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