Within the space provided in each box below label each of th

Within the space provided in each box below, label each of the 4 mutated DNA segment shown according to the type of mutation each represents (use the word bank). Use the codon table above to determine how each mutation would affect the amino acid coding for each segment. Only one mutation can be used for each box, each mutation can be used more than once or not at all. Word Bank Silent mutation Frame shift mutation Messene mutation Nonsense mutation

Solution

1.C instead of A;

Silent mutation.

Silent mutations are mutations in DNA that do not significantly alter the genetic message thereby do not alter phenotype of the organism in which they occur.

Here C replaces A so codon CGU is changed into CGG. But both the codons code for same amino acid, Arginine.

2. T instead of G;

Non sense Mutation.

A mutation in which a codon that corresponds to one of the twenty amino acids specified by the genetic code is changed to a chain-terminating codon.

Here T is inserted instead of G. This replacement of G with T changes the base sequence in DNA as a result of which base sequence ACG which transcribes codon UGC is changed into ACT that transcribes for stop codon UGA. So protien synthesis is terminated prematurely by codon UGA.

3. A instead of G;

Missense mutation.

A missense mutation is a mutation in which a single nucleotide change results in a codon that codes for a different amino acid.

When A is inserted instead of G, it changes the sequence of nucleotides in DNA as a result of which base sequence GGT is changed into AGT. GGT is transcribed into codon CCA, which codes for amino acid proline. But due to base substitution,GGT changes into AGT which is transcribd into codon UCA, that codes for Serine. So a diferent amino acid is inserted in a polypeptide chain. This kind of mutation is called missense mutation.

4. Extra C;

Frameshift mutation.

A mutation caused by the addition or deletion of a base pair or base pairs in the DNA of a gene

Insertion of extra C changes the entire frame of nuleotides in DNA. So different codons are transcribed that codes for different amino acids.