A. Complete the following diagram by giving the template sequence, the mRNA sequ

Question

A. Complete the following diagram by giving the template sequence, the mRNA sequence and peptide sequence.(The genetic code is provided below) (4 marks)

Coding:            5’ GCT GAT CAG CTG ACC GAA GAA CAG ATT 3’

Template:     3’ ___ ___ ___   ___ ___ ___ ___   ___ ___ 5’

mRNA:            5’ ___ ___ ___ ___ ___ ___ ___   ___ ___ 3’

Protein:                  N    _      _         _       _       _       _       _         _      _     C

B. Do you think this sequence is of the beginning of the gene, the middle or the end and why? (2 marks)

C. Using your mRNA sequence from above, introduce each of the following mutations:

            Nonsense

            Missense

            Frameshift

            Transition mutation

In your answer please show both the mutated mRNA sequence and the resulting protein sequence. Highlight the change you made by making the mutated nucleotide bold and underlined

Explanation / Answer

A)

Coding :     5' GCT GAT CAG CTG ACC GAA GAA CAG ATT3'

Template : 3' CGA CTA GTC GAC TGG CTT CTT GTC TAA5'

mRNA :      5'GCU GAU CAG CUG ACC GAA GAA CAG AUU 3'

Protein : ala Asp Gln Leu Thr Glu Glu Gln Ile

B) This sequence is middle of the gene because start codon is AUG code for methionine in eukaryotes and f metthionine in prokaryotes so this sequence is not begining of gene.Stop codons are UAA, UAG and UGA so this sequence is not end of the gene.

C) Non sense mutation: Normal mRNA 5'GCU GAU CAG CUG ACC GAA GAA CAG AUU 3'

                                   Mutated mRNA 5' GCU GAU UAG CUG ACC GAA GAA CAG AUU3'

Non sense mutation: Functional codon is replace by stop codon.

Missense mutation: Change in nucleotide results in substitution of one amino acid to another amino acid.

Normal mRNA 5' GCU GAU CAG CUG ACC GAA GAA CAG CAG AUU 3'

Mutated mRNA 5'GCU GAU CAG CUG AAC GAA GAA CAG CAG AUU 3'

Normal protein Ala Asp Gln Leu Thr Glu Glu Gln Ile

Mutated protein Aln Asp Gln Leu Asn Glu Glu Gln Ile

Frmeshift mutation :Mutation caused by addition or deletion of nucleotide results in shift in reading frame of mRNA.

Normal mRNA 5' GCU GAU CAG CUG ACC GAA GAA CAG AUU 3'

Mutated mRNA 5'GCU GAU CAG CUG ACC AGA AGA ACA GAU U3'

Mutated protein Ala Asp Gln Leu Thr Arg Aga Thr Asp

here addition of A leads to shift in reading frame of mRNA.

Transition mutation :Purine replaced by purine and pyrimidine replaced by pyrimidine.

Normal mRNA 5'GCU GAU CAG CUG ACC GAA GAA CAG AUU3'

Mutated mRNA 5'GCU GAU CGG CUG ACC GAA GAA CAG AUU3'

Mtated protein Ala Asp Arg Leu Thr Glu Glu GLn Ile

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