Section 4: Bioprocess Engineering and Process Biotechnology
Mass transfer in bioprocesses (kLa)
Subtopic: Fundamentals of Mass transfer in bioprocesses (kLa)
Question Statement:
An analysis of DNA-protein interactions was carried out using all DNA -protein complexes
in the protein data bank (PDB). The frequency distribution of four amino acid residues ,
represented as P, Q, R and S, occurring in non-covalent interactions between the protein and
DNA backbone is shown below.
Which one of the following is correct?
(A) P-Lys, Q-Arg, R-Gln, S-Glu (B) P-Gln, Q-Glu, R-Lys, S-Arg
(C) P-Asn, Q-Asp, R-Arg, S-Lys (D) P-His, Q-Glu, R-Gln, S-Lys
Options:
(A) P and Q only
(B) P and R only
(C) R and S only
(D) Q and S only
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2018 Q.37)**
**1. Governing Concept & Question Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (2 Marks)
- **Topic**: Immunology (Cytokines & Endogenous Pyrogens / Fever Induction)
**2. Detailed Step-by-Step Analysis**:
- **Endogenous pyrogens** are cytokine molecules produced primarily by activated immune cells (macrophages, monocytes, and dendritic cells) that travel to the anterior hypothalamus/preoptic area to trigger the production of prostaglandin $E_2$ ($PGE_2$), raising the hypothalamic thermoregulatory set-point and causing fever.
- The classical pro-inflammatory cytokines that act as principal endogenous pyrogens are:
- **P. Tumor Necrosis Factor-$lpha$ (TNF-$lpha$)**: Potent pyrogen inducing both direct and IL-1-mediated fever.
- **Q. Interleukin-1 (IL-1$eta$ / IL-1$lpha$)**: The primary and most potent endogenous pyrogen.
- (Interleukin-6, IL-6, is also an endogenous pyrogen).
- In contrast:
- **R. Transforming growth factor-$eta$ (TGF-$eta$)**: An anti-inflammatory and immunosuppressive/tissue repair cytokine, not a pyrogen.
- **S. Interleukin-10 (IL-10)**: A potent anti-inflammatory cytokine that inhibits pyrogen release and suppresses fever.
- Therefore, **P (TNF-$lpha$) and Q (IL-1) only** are endogenous pyrogens.
- **Option-by-Option Evaluation**:
- **Option (A) [CORRECT]**: P (TNF-$lpha$) and Q (IL-1) are classic endogenous pyrogens.
- **Option (B) [INCORRECT]**: TGF-$eta$ is not an endogenous pyrogen.
- **Option (C) [INCORRECT]**: Neither TGF-$eta$ nor IL-10 are pyrogens; both are immunosuppressive/anti-inflammatory.
- **Option (D) [INCORRECT]**: IL-10 downregulates pyrogenic signaling.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **A**
- **Scoring Criteria**: +2.0 Marks (Negative marking: -0.67 marks).
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