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GATE 2023 BT – Question 13

Genetics, Cellular and Molecular Biology · Molecular Biology: Replication, transcription, splicing, translation, non-coding and micro RNA, RNA interference, DNA damage and repair · 1 mark · Multiple choice

Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion [a]: In multicellular organisms, cells of different lineages have different gene expression profiles. Reason [r]: Alternative splicing is the only mechanism to generate protein diversity.

  1. Both [a] and [r] are false
  2. Both [a] and [r] are true and [r] is the correct reason for [a]
  3. Both [a] and [r] are true but [r] is not the correct reason for [a]
  4. [a] is true but [r] is false

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Correct answer: (D) [a] is true but [r] is false

Explanation

**Assertion [a]:** Cells of different lineages in one organism have the same genome but express different genes, which is what makes them different cell types (a liver cell versus a neuron). **True.**

**Reason [r]:** "Alternative splicing is the **only** mechanism to generate protein diversity." This is false. Protein diversity also comes from multiple genes and gene families, alternative promoters, RNA editing, and post-translational modifications (phosphorylation, glycosylation, proteolytic cleavage). The word "only" makes it incorrect. **False.**

So [a] is true and [r] is false: option **D**.