Question

1. The codon CAA codes for amino acid glutamine. Write the codon(s) obtained after a point mutation that resulted in
   1. Silent mutation          

2. Nonsense mutation    

3. Missense mutation     

4. Define a mutagen and give one example (other than radiation).

5. Describe why UV is particularly damaging to nucleic acids. Is UV a form of ionizing or non-ionizing radiation?

Answer 1

Answer =

Biology

1. The codon CAA codes for amino acid glutamine. Write the codon(s) obtained after a point mutation that resulted in
   1. Silent mutation -

The codon CAA codes for amino acid glutamine

the codon(s) obtained after a point mutation that resulted in silent mutation are CAG

Explanation = Mutation without any apparent change are called as silent mutation.

If a mutation inwhich the new codon specifying the same amino acid as the unmutated codon then it is silent mutation.

If there is change in codon from CAA to CAG there is no change in amino acid .therefore this is silent mutation.

Nonsense mutation =the codon obtained after Nonsense mutation are UAA, UAG,UGA.

Explanation = mutation that changes a codon in a gene to one of the three termination codons UAA,UGA OR UAG is called as nonsense mutation.

Missense mutation = the codon obtained after missense mutation CAT

Explanation - The mutation that alters the codon so that it specifies a different amino acid is known as missense mutation.

=======================================================================================Define a mutagen = Mutagens are chemical or physical agent that increases the occurrence of mutations.

example (other than radiation)are - Biological agents, for example certain virusesor transposable genetic elements.

====================================================================================== UV is particularly damaging to nucleic acids because : it is potent physical agent & generates a number of photoproducts in DNA. UV radiation spectrum has been divided into three wavelength bands UV-A , UV-B & UV-C

UV radiation of 260 nm induces a dimerization of adjacent pyrimidine bases, if these are both thymines resulting in cyclobutyl dimer.

UV a form ofnon-ionizing radiation.