Question

Much important confirmatory evidence on the genetic code has come from assessing changes in the amino acid sequence of mutant proteins after a single base has been changed in the gene that encodes the protein. Which of the listed amino acid replacements would be consistent with the genetic code if the replacements were caused by a single base change? Which cannot be the result of a single-base mutation? Why?
a. Phen Leu (e) llen Leu
b. Lysn Ala (f) Hisn Glu
c. Alan Thr (g) Pron Ser
d. PhenLys

Answer 1

Answer:

The correct answer is -

A. a, c, g

B. e, b, f & d

Explanation:

Part A- the options a, c, g are the options that show mutation or replacement by a single base change

a) Phenylalanine: UUU UUC

Leucine: UUA UUG

Only one base change

c) Alanine:  GCU  GCC  GCC GCG

   Thr:         ACU ACC ACA ACG

only one base change

g) Prolin:  CCU CCC  CCA  CCG

  Serine: UCU UCC  UCA UCG

Part B:

All other replacements will not be consistent with the Genetic Code if single base substitutions occur in option e, b, f & d