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Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance1 Mark
Question
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.
  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
  2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
  3. Assertion is true, but reason is false.
  4. Both assertion and reason are false
Assertion: Initiation step of protein synthesis in prokaryotes and eukaryotes has several differences.
Reason: They both form mRNA - tRNA complex with smaller subunit of ribosome.
✓

Answer

  1. Both assertion and reason are true, but reason is not the correct explanation of assertion

Explanation:

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 - eIF1, eIF2, eIF3, eIF4A, eIF4B eIF4C, eIF4D, eIF4F eIF5 and eIF6

(ii) In eukaryotes, fonnylation of methionine does not take place. In prokaryotes tRNA is charged with formylated methionine. (iii) The larger subunit of ribosome combines with 40 S- 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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