BIOL 2021 Lecture Notes - Lecture 11: Cell Membrane, Gtpase, Protein Kinase

QUESTION 1

Which of the following is an example of an extracellular signal molecule?

2 points

QUESTION 2

Nuclear hormone receptors _____

2 points

QUESTION 3

Which of the following does not occur when a receptor tyrosine kinase is bound by ligand?

2 points

QUESTION 4

Which of these is a logical signal-transduction pathway?

2 points

QUESTION 5

Which of the following is an example of signal amplification?

2 points

QUESTION 6

Consider a signal transduction pathway that utilizes cAMP as a second messenger to activate PKA (Protein Kinase A). Which of the following situations will result in the cellular response?

2 points

QUESTION 7

Which of the following is found in only some signal transduction pathways? [In other words, which is not found in all signal transduction pathways?]

2 points

QUESTION 8

The enzyme that specifically catalyzes the conversion of ATP to cAMP is:

2 points

QUESTION 9

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

2 points

QUESTION 10

A hormone signal is sent from the brain to other parts of the body via the bloodstream. Why do only certain cells respond to this signal?

Tetraethylammonium (TEA) is a drug that blocks voltage-gated potassium channels. What effect would this have on an action potential?

(a)Prevent the rising phase

(b)Prevent the cell from reaching the threshold to trigger an action potential

(c)Prevent or prolong the falling phase

(d)None of the above

The hyperpolarization phase of the action potential is due to:

(a)The opening of voltage-gated Cl- channels

(b)Prolonged opening of voltage gated K+ channels

(c)The closure of resting Na+ channels

(d)Rapid inactivation of voltage-gated K+ channels

The period when it is difficult to initiate another action potential for several milliseconds due to voltage-gated sodium channel inactivation is referred to as the:

(a)Relative refractory period

(b)Absolute refractory period

(c)Resting period

(d)Hyperpolarization period

In the human central nervous system, Gap junctions are found:

(a)Only between neurons

(b)Only between astrocytes

(c)In both neurons and astrocytes

(d)In all cells

Small molecule transmitters such as acetylcholine are synthesized in:

(a)The nerve terminal

B) The cell body and transported to the nerve terminal

C) Synaptic vesicles

D) Endoplasmic reticulum

Prior to Otto Loewi’s classical experiment, which of the following was not known:

(a)stimulation of the vagus nerve slows the heart

(b)extracts of frog heart, made following vagal nerve stimulation, slow the heart

(c)some acetylcholine effects are similar to those produced by muscarine

(d)vagal nerve stimulation releases a substance which slows the heart

Which of the following is most important in determining if neurotransmission is excitatory or inhibitory?

(a)The structure of the synapse

(b)The neurotransmitter released by the presynaptic neuron

(c)The neurotransmitter receptor

(d)The strength of the stimulus

Benzodiazepines such as Valium allosterically regulate GABA receptors by:

(a)Binding at receptor sites other than the transmitter binding site

(b)Binding at the transmitter (GABA) binding site on the receptor

(c)Blocking the action of the endogenous transmitter

(d)Mimicking the action of the endogenous transmitter

GABA-A receptors are ligand-gated Cl- channels. The equilibrium potential of Cl- is -65 mV. At the neuronal resting membrane potential of -65 mV, GABA binding to the GABA-A receptor would result in the opening the Cl- channel, resulting in:

(a)no net flow of Cl- ions

(b)Cl- inflow and hyperpolarization

(c)Cl- outflow and depolarization

(d)Cl- outflow and hyperpolarization

At the mammalian neuromuscular junction, the released neurotransmitter acts on:

(a)muscarinic receptors

(b)nicotinic receptors

(c)adrenergic receptors

(d)Beta receptors

Neurotransmitters are packaged into synaptic vesicles by:

(a)endocytosis following transmitter release

(b)presynaptic membrane transporters

(c)vesicular transporters

(d)all of the above

. Which of the following are NOT types of ion channels?

Voltage-gated

(a)Ligand-gated

(b)G protein coupled receptor (GPCR)-gated

(c)Leak channels

(d)NONE of the above

NMDA receptors are unique in that their ion channel is:

(a)Ligand-gated

(b)Voltage-gated

(c)Ligand- and voltage-gated ion channels

(d)GPCR-gated

. Which of the following is INCORRECT regarding Catecholamine neurotransmitters

(a)Includes Dopamine, Norepinerphrine, and Epinephrine

(b)Contain a Catechol Ring

(c)Synthesized from Tryptophan

(d)Are produced by neurons whose cell bodies are located in the upper brainstem

The largest and most diverse group of receptors in eukaryotes is:

(a)Ligand gated receptors

(b)Glutamate receptors

(c)G-Protein coupled receptors

(d)Allosteric receptors

The most abundant G-protein coupled receptor in the brain is:

(a)Glutamate receptors

(b)Acetylcholine receptors

(c)Cannabinoid receptors

(d)Dopamine receptors

Which of the following drugs DOES NOT block voltage-gated Na+ channels

(a)Lidocaine

(b)Riluzole

(c)Reserpine

(d)Tetrodotoxin

Sarin, a nerve gas, exerts its toxicity by:

(a)blocking nicotinic receptors

(b)inhibiting choline acetyltransferase

(c)inhibiting acetylcholinesterase

(d)inhibiting voltage-gated Na+ channels

Botulinum Toxin (BoTox) interferes with transmitter release by:

(a)cleaving protein(s) involved in transmitter release

(b)blocking voltage-gated Ca2+ channels

(c)blocking voltage-gated Na+ channels

(d)blocking voltage-gated K+ channels

Atropine is:

(a)An agonist of the acetylcholine ionotropic receptor

(b)An antagonist of the acetylcholine ionotropic receptor

(c)An agonist of the acetylcholine metabotropic receptor

(d)An antagonist of the acetylcholine metabotropic receptor

33 Different glycoproteins can have a diverse array of oligosaccharides. Which of the statements below for making glycoproteins on plasma membrane is true?

(a) Extensive modification of oligosaccharides occurs in the extracellular space.

(b) Initial oligosaccharide chains are made by addition of one sugar at a time onto the protein in the ER lumen.

(c) Each layer of Golgi membrane structures contains identical modification enzymes for modifying sugar chain on proteins.

(d) ER lipids can be modified by sugar chain, which can be used for sugar chain modification of the proteins.

34 In a multicellular organism, when a signal needs to be sent to most cells the signal most suited for this is a ___________.

(a) neurotransmitter.

(b) hormone.

(c) dissolved gas.

(d) plasma membrane anchored ligands.

35 Typically, members of the steroid hormone receptor family __________________.

(a) are cell-surface receptors.

(b) do not undergo conformational changes by binding to their ligands.

(c) are found mainly in the nucleus when ligand is not available.

(d) interact with signal molecules that diffuse through the plasma membrane

36 Which of the following statements about what happens when a G-protein-coupled receptor activates a hetero trimeric G protein is true?

(a) The β subunit exchanges its bound GDP for GTP.

(b) The GDP bound to the α subunit is phosphorylated to form bound GTP.

(c) The α subunit exchanges its bound GDP for GTP.

(d) It activates the α subunit and inactivates the βγ complex

37 Which of the following statements about signal transduction is false

(a) Ca2+ concentration in cytosol will increase when PLC (Phospholipase C) is activated by signal.

(b) Cyclic GMP is made in smooth muscle cells when they received NO signal.

(c) SH2 domain containing proteins can be expected to interact activated RTK.

(d) Ligand binding to RTK activates its enzyme activity then the activated RTK phosphorylates tyrosine residues on itself.