Question

Bis 101 help

Question 6 1 pts 6. (1pts) The following DNA sequence 5- AGTCGCCCATGCCG-3'undergoes a mutation in which an A nucleotide is inserted at the 5' end of the molecule. How would you classify this mutation? Frameshift mutation Silent mutation Nonsense Mutation Missense mutation D Question 7 2 pts 7.(2 pts) Below is a DNA sequence encoding an mRNA strand. What are the first four amino acids that this sequence codes for? (Not that the coding strand has been labeled). 5 TACTTCTGGCATATC-3

Answer 1

Question 6 1 pts 6. (1pts) The following DNA sequence 5- AGTCGCCCATGCCG-3' undergoes a mutation in which an A nucleotide is inserted at the 5' end of the molecule. How would you classify this mutation? Frameshift mutation Silent mutation Nonsense Mutation Missense mutation

Ans. The correct option is A). Frameshift mutation.

DNA sequence without mutation 5`-AGT CGC CCA TGC CG-3` specify for 4 codons.

DNA sequence with mutation i.e. A inserted at 5` end 5`-AAG TCG CCC ATG CCG-3` specify for 5 codons.

The original DNA sequence specifies for 4 codons hence 4 amino acids in total and an incomplete codon. Whereas the mutated DNA with A inserted at the 5` end will code for a total of 5 codons hence 5 amino acid sequence.

Due to the mutation there is a change in the frame, thus this is frameshift mutation. Due to this kind of mutation the amino acid sequence are also altered as due to the change in frame the codon sequence is changed.

Other options are incorrect:

Silent mutation alters a codon such that it is changed to a new codon. But the new codon also codes for the same amino acid.

Nonsense mutation is a kind of mutation in which the point mutation lead to the formation of termination codon i.e. early termination of translation so a shorter protein is formed.

Missense mutation is a mutation that alter a codon so it specifies a new amino acid.