Principle Of Inheritance And Variation Question 175
Question: Assertion : UAA, UAG and UGA terminate protein synthesis. Reason : They are not recognised by tRNA.
Options:
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
Show Answer
Answer:
Correct Answer: A
Solution:
Synthesis of polypeptide terminates when a nonsense codon of mRNA reaches the A - site.
There are three nonsense codons - UAA, UAG and UGA.
These codons are not recognised by any of the tRNAs.
Therefore, no more aminoacyl tRNA reaches the A- site.
The P-site tRNA is hydrolysed and the completed polypeptide is released in the presence of release factor.
Thus termination occurs.
BETA
