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Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance1 Mark
MCQ
For question, two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Initiation step of protein synthesis in prokaryotes and eukaryotes has several differences.
Reason: They both form $\text{mRNA - tRNA}$ complex with smaller subunit of ribosome.
  • A
    Both assertion and reason are true, and reason is the correct explanation of assertion.
  • ✓
    Both assertion and reason are true, but reason is not the correct explanation of assertion.
  • C
    Assertion is true, but reason is false.
  • D
    Both assertion and reason are false
✓

Answer

Correct option: B.
Both assertion and reason are true, but reason is not the correct explanation of assertion.
The differences between initiation step of protein synthesis in eukaryotes and prokaryotes are : $(i)$ In prokaryotes initiation factors are three $IF1, IF2$ and $1F3$. Eukaryotes have at least ten initiation factors $- \text{eIF1, eIF2, eIF3, eIF4A, eIF4B eIF4C, eIF4D, eIF4F eIF5}$ and $\text{eIF6}$
$(ii)$ In eukaryotes, fonnylation of methionine does not take place. In prokaryotes $\text{tRNA}$ is charged with formylated methionine. $(iii)$ The larger subunit of ribosome combines with $40 S- \text{mRNA-tRNA}$ Met $($in case of prokaryotes, $30 S)$ complex to form intact ribosome. It requires initiation factor $IF1$ in prokaryotes and factors $eIF1\ eIF4\ (A, B, C)$ in eukaryotes.

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