37. Attenuation is a mechanism involved in the regulation of tryptophan operon in E. coli. When tryptophan levels are high in the cell, region 2 of the trpL is blocked […]
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CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Tryptophan Synthase Activity in E. coli: Regulation When Glucose and Tryptophan Are Present
36. E.coli are growing in a medium with glucose as the sole carbon source. Tryptophan suddenly added. The cells continue to grow, and divide every 30 minutes. What will be […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Deletion of the Leader Sequence in the trp Operon: Effects on Tryptophan Biosynthesis in E. coli
35. Deletion of the leader sequence of trp operon of E. coli would result in (1) decreased transcription of trp operon. (2) increased transcription of trp operon. (3) no effect […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
The trp Operon in E. coli: A Model of Repressible Gene Regulation with Double Controls
34. The tryptophan operon in E. coli is an example of (1) inducible operon, controlled by a repressor protein and attenuation. (2) repressible operon, controlled by a repressor protein and […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Attenuation in the Trp Operon: How Bacteria Fine-Tune Tryptophan Synthesis
33. During regulation of trp operon by attenuation there is (1) Pre-mature termination of translation (2) pre-mature termination of transcription (3) Termination of replication (4) Ribosome fails to read transcript […]
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How Do Peptides with D-Amino Acids Arise in Cells? Mechanism and Biological Significance
32. Some cells possess peptides which contain D-form of amino acids. How do they arise? (1) These peptides are produced by ribosomes by incorporating D- amino acids at specific positions. […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Attenuation in the trp Operon: The Molecular Mechanism Behind Early Transcription Termination in E. coli
32. When tryptophan in excess most of times RNA polymerase dismount after transcription of first 150 nt in trp operon. This is termed as (1) Anti-termination (2) Attenuation (3) Catabolite […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
When Is Tryptophan Synthase Induced in a trp-lac Chimeric Operon? Understanding the Role of Lactose and Glucose
You have created a fusion between the trp operon, which encodes the enzymes for trptophan biosynthesis, under the regulatory control of the lac operator. Under which of the following conditions […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Prokaryotic Stress Response: PerR, RecA, Heat Shock Proteins, and Chaperonins in Oxidative, Acidic, and Thermal Stress
31.Following statements were made about stress response in prokaryotes: A. PerR functions as a major peroxide sensor in many Gram- positive bacteria. B. Extreme acidic pH induces RecA-mediated DNA damage, […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
How Operator and Structural Gene Mutations Affect Tryptophan Synthesis in E. coli: The trpR+ trpO- trpE+ / trpR+ trpO+ trpE- Case
30. A heterozygote of E.coli was produced with the following combination of mutations: trpR+ trpO– trpE+ / trpR+ trpO+ trpE– Where R is the repressor, O is the operator and […]
