TBL MCQs Flashcards
Which molecule is associated with the alpha subunit of an active GPCR?
A) GDP
B) GTP
C) GMP
D) GAP
B) GTP
Which of the following is a rapid cellular response to increased cAMP levels?
A) Alteration of gene expression
B) Activation of transcription factors
C) Glycogen breakdown in skeletal muscle
D) Long-term memory formation
C) Glycogen breakdown in skeletal muscle
What small molecules are generated as a result of some G protein interactions with target enzymes?
A) Adenylyl cyclase
B) ATP
C) GTP
D) cAMP
D) cAMP
Which of the following statements best describes the difference between G proteins interacting with ion channels and enzymes?
A) Interaction with ion channels causes immediate changes to the cell state and function, whereas enzyme interactions are less rapid and often involve second messenger molecules.
B) Interaction with ion channels cause less rapid changes to the cell state adn function, whereas enzyme interactions lead to immediate alterations through second messenger molecules.
C) Interaction with ion channels and enzymes both cause immediate changes to the cell state and function without involving second messenger molecules
D) Interaction with ion channels and enzymes both cause immediate changes to the cell state and function through the involvement of second messenger molecules.
A) Interaction with ion channels causes immediate changes to the cell state and function, whereas enzyme interactions are less rapid and often involve second messenger molecules.
How are GCPRs involved in the slowdown of the heartbeat?
A) By binding to neurotransmitters like acetylcholine, which activate GPCRs on cardiac cells, leading to the openning of potassium channels and the depolarisation of the cell membrane, thus decreasing heart rate.
B) By directly inhibiting the release of adrenaline, which in turn reduces the activation of GPCRs on cardiac cells, leading to decreased heart rate.
C) By blocking the activation of GCPRs on cardiac cells, preventing the release of calcium ions from intracellular stores, thereby decreasing contractility and heart rate.
D) By binding to neurotransmitters like acetylcholine, which activate GPCRs on cardiac cells, leading to the openning of potassium channels and the hyperpolarisation of the cell membrane, thus decreasing heart rate.
D) By binding to neurotransmitters like acetylcholine, which activate GPCRs on cardiac cells, leading to the openning of potassium channels and the hyperpolarisation of the cell membrane, thus decreasing heart rate.
Opening of potassium channels = hyperpolarisation
What is a tyrosine kinase domain?
A) A domain that removes phosphate groups from tyrosine residues
B) A domain that phosphorylates tyrosine amino acid residues by adding a phosphate group.
C) A domain which binds to tyrosine amino acid residues
D) A domain that allows high affinity binding to PIPs
E) A domain which adds tyrosine residues to itself
B) A domain that phosphorylates tyrosine amino acid residues by adding a phosphate group.
Which of the following phrases about activated Akt is true?
A) Through a series of signalling events, the activation of Akt results in the downstream inactivation of mTor.
B) Activated Akt is tyrosine kinase which phosphorylates Bad.
C) The phosphorylation of Bad by Akt activates it to release Bcl2.
D) The Pleckstrin Homology domain of Akt allows it to use PIP2 as a docking site.
E) Akt can act as an integrator of multiple signalling pathways.
E) Akt can act as an integrator of multiple signalling pathways.
Chose the best combination of words to fill the gaps: The first step of the MAP kinase cascade involves Raf (MAP kinase kinase kinase) which phosphorylates and activates ____ through the process of ____ by adding a phosphate group.
A) Mek, GTP hydrolysis
B) Erk, ATP hydrolysis
C) Erk, GTP hydrolysis
D) Mek, ATP hydrolysis
E) Itself, ATP hydrolysis
D) Mek, ATP hydrolysis
Which two of the following are examples of amplification in the Ras/MAPK signalling pathway?
A) Grb2 activating Ras-GEF (Sos)
B) The MAP kinase (Raf) activating other MAP kinases (Mek)
C) A MAP kinase (Erk) phosphorylating target proteins.
D) The docking of Grb2 to a phosphotyrosine on HER2
B) The MAP kinase (Raf) activating other MAP kinases (Mek)
C) A MAP kinase (Erk) phosphorylating target proteins.
Which statement is correct?
A) IP3 binding to calcium channels on the endoplasmic reticulum reduces cytosolic concentrations of calcium.
B) Phospholipase C docks indirectly onto the receptor tyrosine kinase
C) Phospholipase C is activated through dephosphoylation.
D) DAG is release into the cytosol.
E) Phospholipase C uses PIP2 as a substrate to generate DAG and IP3.
E) Phospholipase C uses PIP2 as a substrate to generate DAG and IP3.
How do ligand-gated ion channels convert chemical signals into electrical signals in neuronal signalling?
A) Ligand binding does not play a role in converting chemical signals into electrical signals.
B) Ligandbinding induces conformational changes, opening the ion channel and allowing specific ions to enter or exit, altering membrane potential.
C) Ligand binding initiates a release of neurotransmitters, generating electrical signals across the synapse.
D) Ligand binding inhibits electrical signals by preventing ion movement through the channel.
B) Ligandbinding induces conformational changes, opening the ion channel and allowing specific ions to enter or exit, altering membrane potential.
Which statement is correct?
A) The acetylcholine receptor opens in response to acetylcholine binding, allowing sodium ions to enter and hyperpolarise the membrane.
B) The acetylcholine receptor opens in response to acetylcholine binding, allowing chloride ions to enter and depolarise the membrane.
C) The glycine transmitter-gated ion channel opens in response to acetylcholine binding, allowing chloride ions to exit and hyperpolarise the membrane.
D) The glycine transmitter-gated ion channel opens in response to acetylcholine binding, allowing chloride ions to enter and hyperpolarise the membrane.
D) The glycine transmitter-gated ion channel opens in response to acetylcholine binding, allowing chloride ions to enter and hyperpolarise the membrane.
Entrance of chloride = hyperpolarisation
Which of the following statements accurately describes the intricacies of ligand binding and conformational changes in ligand -gated ion channels?
A) Ligand binding is solely responsible for channel closure.
B) Conformational changes are determined by the membrane potential.
C) Ligand binding induces conformational changes leading to channel opening.
D) Conformational changes occur randomly and are not influenced by ligand presence.
C) Ligand binding induces conformational changes leading to channel opening.
Drug X is a drug that causes complete depletion of extracellular glucose levels. In the presence of drug X, which phase of the cell cycle would the cell be arrested in?
A) G1 phase
B) S phase
C) G2 phase
D) M phase
E) None of the above
A) G1 phase
