Which of the following is not possible in biological systems?

• DNA → RNA → Protein

• Protein → RNA → DNA

• Glucose → Amino acid → Proetin

• RNA → DNA → Protein

Which cyclin is involved in formation of pre-transcriptional enhancer binding protein (PTEB)?

• Cyclin D

• Cyclin K

• Cyclin E

• Cyclin T

Puromycin blocks translation. Mode of action of drug puromycin is

• binds to A site and stop elongation

• Stops peptidyl transferase activity

• Binds EF-Tu-GTP and prevent initiation

• Do not allow termination of translation

Somatic hypermutation in immunoglobulin genes is responsible for

• Class witching

• Affinity maturation

• Clonal selection

• VDJ recombination

Interaction of antibody with antigen is like lock and key. The major force responsible for antigen antibody interaction is

• Hydrogen bond

• Van der wall interaction

• Disulphide bond

• Peptide bond

Which is common cytokine secreted by both TH1 and TH2 cells?

• IL-2

• IL-4

• INF-γ

• IL-5

Major Histocompatibility complex - I (MHC-I) is present at

• All nucleated cells

• Only on antigen presenting cells

• Only on B and T lymphocytes

• Macrophages and dendritic cells

Major reason for evolution for diversity in immune system is

• natural selection

• Neutral mutation

• Directed evolution

• Co-evolution

Which of the cyclins have/ has essential functions in S phase of cell cycle?

• A type

• B type

• D type

• Both B and D type

During generation of an action potential, depolarization is due to

• K+ efflux

• Na+ efflux

• Na+ influx

• K+ influx