Section 4: Bioprocess Engineering and Process Biotechnology
Bioreactor types, scale-up
Subtopic: Fundamentals of Bioreactor types, scale-up
Question Statement:
Let y(t) be a bacterial population whose growth is given by
dy
dt = 𝜆(y + 2)
where 𝜆 is the growth rate constant. If y(0) = 1 and y(1) = 4, then the value of
𝜆 is
Options:
(A) ln 2
(B) ln 3
(C) ln 4
(D) ln 6
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2025 Q.13)**
**1. Governing Concept**:
- **Topic**: Molecular Biology & Post-Transcriptional Processing of Eukaryotic mRNA
- Pre-mRNA synthesized by RNA Polymerase II undergoes three major co-transcriptional/post-transcriptional processing events:
1. **$5'$ Capping**: Addition of 7-methylguanosine via an unusual $5'-5'$ triphosphate linkage.
2. **$3'$ Polyadenylation**: Cleavage at poly(A) signal (AAUAAA) followed by addition of ~200–250 adenine residues by poly(A) polymerase.
3. **Splicing**: Excision of non-coding introns and ligation of coding exons by the **spliceosome** (U1, U2, U4/U6, U5 snRNPs).
**2. Option Analysis**:
- **Option (A) is INCORRECT**: Ribosomes catalyze translation, not splicing.
- **Option (B) is INCORRECT**: Topoisomerases relieve topological torsional strain in DNA.
- **Option (C) is CORRECT**: The spliceosome specifically catalyzes pre-mRNA intron removal.
- **Option (D) is INCORRECT**: Chaperones fold polypeptides.
**3. Final Answer**:
- **Correct Choice**: **C**
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