Question

A) In how many cases in the genetic code would you fail to know the amino acid specified by a codon if you knew only the first two nucleotides of the codon?
b) In how many cases would you fail to know the first two nucleotides of the codon if you knew which amino acid is specified by it?

Answer 1

Answer:

a) 28 cases

b)  3 cases

Explanation:

a) From the table of genetic codes, there are 28 codons that specify more than one amino acid assuming only the first two nucleotides are considered. In these cases, one cannot outrightly specify the amino acid the genetic codes are coding for without knowing the last nucleotide of the codes. For example, UU can be for Phenylalanine or Leucine, CA can be for Histidine or Glutamine, etc.

b) From the table of genetic codes, the first two nucleotides of Arginine can be either of CG or AG, that of Serine can be either of UC or AG while that Leucine can be either of CU or UU. Only in these 3 cases would one fail to know which are the first two nucleotides assuming the name of the amino acids are given.

See the attached image for the genetic code.