MCQ on Cell signaling with answers- Set 1

MCQ on Cell signaling with answers – Set 1

Q) When a hormone binds to a specific receptor on the cell membrane, all of the following might occur EXCEPT

  1. The initiation of a covalent bond between the receptor and the hormone
  2. The initiation of a specific signal transduction pathway
  3. The inhibition of control enzymes controlling certain pathways
  4. The activation of control enzymes controlling certain pathways
  5. The activation or repression of transcription factors

Answer: Option 1

Q) The endogenous GTPase activity of G-proteins serves to:

  1. Stimulate the activity of enzymes by producing energy.
  2. Synthesize cGMP as a second messenger
  3. Synthesize GTP as an energy source.
  4. Hydrolyze GTP returning the G protein to a pre-stimulated level of activity

Answer: Option 4

Q) The major difference between hormones that have intracellular receptors and those that have cell membrane receptors is that the former tend to be

  1. Larger
  2. Charged
  3. Amino acid derivatives
  4. Proteins
  5. Hydrophobic

Answer: Option 5

Q) Some receptors for growth factors activate a protein kinase cascade, with the participation of multiple enzymes to effect a change in gene expression. Which of the following statements about a protein kinase cascade are true?

  1. Multiple steps allow the amplification of the signal.
  2. Multiple steps in an activation mean that abnormal stimulation of a cell response such as growth can occur with mutations in more than one gene
  3. External signals can lead to changes in gene expression
  4. Multiple steps leading to kinase activations can result in cells having different responses, depending on the presence or absence of target proteins.
  5. All of the above

Answer: Option 5

Q) The reaction catalyzed by Phospholipase C can use all of the following EXCEPT

  1. Phosphitidylinositol bisphosphate as a substrate
  2. Diacylglycerol as a product
  3. Diacylglycerol phosphate as a product
  4. Inositol trisphosphate as a product
  5. Water as a substrate

Answer: Option 3

Q) When epinephrin or glucagon bind to their receptor on the membrane and activate the cAMP cascade, all of the following happen EXCEPT

  1. GDP dissociates from G-protein and GTP associates with G-protein
  2. The alpha-subunit of G-protein activates adenylate cyclase and cAMP is produced
  3. G-protein is freed from its tether and diffuses away from the cell membrane
  4. The alpha-subunit of G-protein hydrolyzes GTP and becomes inactive (will no longer bind adenylate cyclase)
  5. The alpha-subunit of G-protein bound to GDP must reassociate with the beta and gamma-subunits before binding to the occupied receptor

Answer: Option 3

Q) Which of the following is a nuclear receptor protein?

1. Steroid receptor
2. Adhesion receptor
3. Serpentine receptor
4. Receptor with no intrinsic enzyme activity

Answer: Option 1

Q) Receptor proteins that indirectly activate enzymes that generate intracellular second messengers are
1. Steroid receptors
2. Serpentine receptors
3. Adhesion receptors
4. Receptor enzymes

Answer: Option 2

Q) Number of affected molecules increases geometrically in an enzyme cascade in
1. Specificity
2. Amplification
3. Adaptation
4. Integration

Answer: Option 2

Q) Signal molecule fits the binding site on its complementary receptor called as
1. Specificity
2. Amplification
3. Integration
4. Cooperativity

Answer: Option 1





Leave a Reply

Your email address will not be published. Required fields are marked *