Principle Of Inheritance And Variation Question 549
Assertion : Initiation step of protein synthesis in prokaryotes and eukaryotes has several differences. Reason : They both form mRNA - ribosome complex with smaller subunit of ribosome.
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
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Answer:
Correct Answer: B
Solution:
The differences between initiation step of protein synthesis in eukaryotes and prokaryotes are : (i) In prokaryotes initiation factors are three - IF1, IF2 and IF3.
Eukaryotes have at least ten initiation factors - eIF1, eIF2, eIF3, eIF4A, eIF4B, eIF4C, eIF4D, eIF4E, eIF4F, eIF5 and eIF6.
(ii) In eukaryotes, formylation of methionine does not take place.
In prokaryotes tRNA is charged with formylated methionine.
(iii) The larger subunit of ribosome combines with $ 30S-mRNA-tRNA^{Met} $ (in case of prokaryotes, 40S) complex to form intact ribosome.
It requires initiation factor IF1 in prokaryotes and factors eIF1, eIF4 (A, B, C) in eukaryotes.
BETA
