4.The basic difference between direct repair and base excision repair is (1) Direct repair restores original structure of altered nucleotide without replacement, while in base excision repair the section of […]
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CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Photoreactivation: Direct Repair of UV-Induced Pyrimidine Dimers Without Nucleotide Removal
Pyrimidine dimers formed due exposure to UV rays can be directly repaired without removing any nucleotide by the repair mechanism known as (1) Mismatch repair mechanism (2) Photo-activation (3) Base […]
CSIR NET Life Science Previous Year Questions and Solution on DNA REPLICATION
Predicting DNA Banding Patterns in CsCl Gradient if DNA Replication Were Conservative: A Meselson-Stahl Perspective
The semi-conservative nature of DNA replication was established by Meselson and Stahl in their classic experiment with bacteria. They grew bacteria in N15-NH4Cl containing medium, washed and then incubated in […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Photolyase Repairs UV-B Induced Pyrimidine Dimers Using Blue Light: The Science Behind DNA Repair
UV-Binduced damage of DNA by formation ofpyrimidine dimmers are repaired by photolyase on absorbing (1) UV -C light (2) Green light (3) Blue light (4) IR light How Photolyase Repairs […]
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Photolyase: The Key Enzyme in Direct Repair of Ultraviolet-Induced DNA Damage
Which enzyme is involved in direct repair mechanismagainst ultraviolet-induced DNA damage? (1) RNA polymerase (2) Uvr ABC (3) Restriction endonuclease (4) Photolyase Correct Answer: Photolyase (Option 4) […]
CSIR NET Life Science Previous Year Questions and Solution on DNA REPLICATION
DNA Banding Patterns in CsCl Density Gradient After E. coli Shift from N15 to N14 Medium
E. coli cells were grown in N15 medium for several generations and then shifted to normal medium for one generation. If the DNA isolated from the culture would be centrifuged […]
CSIR NET Life Science Previous Year Questions and Solution on DNA REPLICATION
How 15N/14N Density Gradient Experiment Demonstrates Semi-Conservative DNA Replication
You have labelled DNA in a bacterium by flowing cells in medium containing either 14N nitrogen or the heavier isotope, 15N. Furthermore, you have isolated pure DNA from these organisms, […]
CSIR NET Life Science Previous Year Questions and Solution on DNA REPLICATION
How DNA Polymerases Correct Replication Errors Using 3′→5′ Exonuclease Proofreading Activity
11. Copying errors occurring during replication are corrected by the proof reading activity of DNA polymerases that recognize incorrect bases (1) at the 5′ end of the growing chain and […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
Comparing Lysogenic and Lytic Cycles of Bacteriophage Lambda and P1 in E. coli
22. Bacteriophage λ and Pl are both temperate phages. Which one of the following statements made about these phages and their lytic and lysogeny cycles in E. coli is INCORRECT? […]
CSIR NET Life Science Previous Year Questions and Solution on Molecular Biology
How CI and Cro Proteins Regulate Gene Expression via OR1, OR2, and OR3 in Bacteriophage Lambda
21. Bacteriophage λ proteins, Cl and Cro are crucial regulators of the lysogeny and lytic cycles of the bacteriophage. These proteins bind to the rightward operator region consisting of OR1, […]
