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Question 1

Which of the following statements is not true about receptors?

a) Most receptors are proteins situated in the cell membrane.

b) Receptors contain a hollow or cleft on their surface which is known as a binding site.

c) Receptors bind chemical messengers such as neurotransmitters or hormones.

d) Receptors catalyse reactions on chemical messengers.

Question 2

Which of the following statements is not true about neurotransmitters?

a) Neurotransmitters are released by nerves.

b) Neurotransmitters are required to carry a 'message' from a nerve to a target cell.

c) Neurotransmitters have significant distances to cover to reach their target cells.

d) Neurotransmitters bind to receptors on target cells.

Question 3

Which of the following is not a neurotransmitter?

a) acetylcholine

b) cyclic AMP

c) noradrenaline

d) dopamine

Question 4

Which of the following statements is not true regarding the binding site of a receptor?

a) The binding site is normally a hollow or cleft in the surface of a receptor.

b) The binding site is normally hydrophobic in nature.

c) Chemical messengers fit into binding sites and bind to functional groups within the binding site.

d) The binding site contains amino acids which are important to the binding process and a catalytic mechanism.

Question 5

Which of the following statements is not true about a ligand-gated ion channel receptor?

a) Ligand-gated ion channel receptors are present in the cell membrane.

b) Neurotransmitters can act as the chemical messengers for ligand-gated ion channels.

c) Ligand-gated ion channels consist of five glycoproteins.

d) Differences in membrane potential affect whether ligand-gated ion channel receptors open or close.

Question 6

Which of the following statements is true about a G-protein coupled receptor?

a) It contains five transmembrane hydrophobic sections.

b) There are more extracellular loops than intracellular loops.

c) The binding region for the G-protein involves two extracellular loops.

d) The N-terminal chain is extracellular and the C-terminal chain is intracellular.

Question 7

Which of the following is not a G-protein coupled receptor?

a) The muscarinic receptor.

b) The glycine receptor.

c) The adrenergic receptor.

d) The glutamate receptor.

Question 8

Which of the following statements is not true about G-protein coupled receptors?

a) They generally mediate the action of fast acting neurotransmitters.

b) They mediate the action of some hormones.

c) They activate signal proteins called G-proteins.

d) Histamine can act as a ligand for some G-protein coupled receptors.

Question 9

Which of the following pairs of receptors are likely to show the greatest structural similarity?

a) The dopamine receptor subtypes D₃ and D₅.

b) The M₂muscarinic receptor and the β₂-adrenergic receptor .

c) The H₂ histamine receptor and the α₁-adrenoceptor.

d) The H₁histamine receptor and the β₂ adrenoceptor.

Question 10

Which of the following pairs of receptors illustrates convergent evolution?

a) The D₂ and D₃-dopaminergic receptor subtypes.

b) The D₄ and D₅-dopaminergic receptor subtypes.

c) The β₁ and β₂-adrenoceptor subtypes.

d) The M₃ and M₅-muscarinic receptor subtypes.

Question 11

Which of the following reactions is catalysed by a protein kinase?

a) The phosphorylation of alcohol groups in protein substrates.

b) The hydrolysis of phosphate groups in protein substrates.

c) The phosphorylation of alcohol groups in carbohydrates.

d) The hydrolysis of phosphate groups in ATP and GTP.

Question 12

Which of the following statements is true about a tyrosine kinase linked receptor?

a) It is situated in the cytoplasm.

b) The N-terminal chain is intracellular.

c) The ligand binding site is in the N-terminal chain.

d) It has two hydrophobic transmembrane regions.

Question 13

Which of the following is not a typical messenger for a tyrosine kinase linked receptor?

a) insulin

b) acetylcholine

c) growth factors

d) cytokines

Question 14

Which of the following statements is true regarding intracellular receptors?

a) They consist of three protein subunits.

b) They contain a ligand binding site near the C-terminal end.

c) They contain a binding region for DNA near the N-terminal end.

d) They are activated by hydrophobic molecules which are synthesised within the cell.

Question 15

Which of the following statements is true regarding the DNA binding region of intracellular receptors?

a) It contains five cysteine residues.

b) Four cysteine residues are involved in binding two zinc ions.

c) It identifies particular nucleotide sequences in DNA.

d) The DNA binding region is known as having 'thiol fingers'.

Oxford University Press, Online Resource Centre, Chapter 04.

Chapter 04

Instructions