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- Which one of the following statements is correct?
A) Drugs and drug targets generally have similar molecular masses. B) Drugs are generally smaller than drug targets. C) Drugs are generally larger than drug targets. D) There is no general rule regarding the relative size of drugs and their targets.
- The hormone adrenaline interacts with proteins located on the surface of cells and does not cross the cell membrane. However, larger steroid molecules, such as estrone, cross cell membranes and interact with proteins located in the cell nucleus. Why is estrone able to cross the cell membrane when a smaller molecule such as adrenaline cannot?
HO
OH
NH
HO
adrenaline
HO
O
estrone
A) Adrenaline is repelled by the hydrophilic cell membrane. B) Adrenaline has a higher melting point than does estrone. C) Adrenaline is a synthetic drug, and synthetic drugs never cross membranes. D) Estrone is less polar than adrenaline.
- The strongest intermolecular interactions are generally considered to be…
A) hydrophobic interactions. B) covalent bonding. C) hydrogen bonding. D) dipole-dipole interactions. E) electrostatic interactions.
- Which interaction shown below is most likely to be driven by entropy?
N
O
drug
NH 3
OOC
drug
H
H
drug
drug
A B
C D
O
drug
O
- Consider answer A to the question above. The ammonium group in the form shown in the binding site is best described as a…
A) weak base. B) binding group. C) hydrogen bonding acceptor. D) binding region. E) hydrophobic group.
- Shown below is a portion of a polymer made exclusively from the amino acid glycine. The left and right sides of the polymer have been covered up by black boxes. The boxes are not drawn to scale. On which side of the polymer is the N-terminus located?
H
N
N
H
H
N
O
O
left O right
A) Left B) Right C) Cannot be determined from the information given
- Which one of the following statements about a peptide bond is correct?
A) It is not planar. B) It is capable of forming a hydrogen bond. C) The cis configuration is favoured over a trans configuration. D) Single-bond rotation is permitted between nitrogen and the carbonyl group.
- The tertiary structure of a protein is maintained by…
A) intermolecular interactions and intermolecular disulfide linkages. B) intramolecular interactions and intermolecular disulfide linkages. C) intermolecular interactions and intramolecular disulfide linkages. D) intramolecular interactions and intramolecular disulfide linkages.
H 2 N COOH
glycine
- From an energetic standpoint, enzymes can catalyze reactions by…
A) decreasing the energy of the substrate and increasing the energy of the transition state. B) decreasing the energy of the substrate and decreasing the energy of the transition state. C) increasing the energy of the substrate and increasing the energy of the transition state. D) increasing the energy of the substrate and decreasing the energy of the transition state.
- Which one of the following statements best describes an induced fit?
A) The process by which an active site alters shape such that it is ready to accept a substrate. B) The process by which a substrate adopts the correct binding conformation before entering an active site. C) The process by which a substrate binds to an active site and alters the shape of the active site. D) The process by which an active site alters the shape of the substrate such that it can adopt the necessary active conformation for binding.
- Which one of the following is least likely to act as a source of an acid in the active site of an enzyme?
Side chains: (^) Glu COOH
Asp COOH
Lys
NH 2
His N
NH
A) The side chain of glutamic acid in its neutrally charged form B) The side chain of histidine in its positively charged form C) The side chain of aspartic acid in its neutrally charged form D) The side chain of lysine in its neutrally charged form
- Which statement about receptors is incorrect?
A) Agonists are drugs that have the same effect on a receptor as the endogenous chemical messenger. B) Desensitization occurs when an agonist is bound for a long period of time. C) In the absence of anything bound to a receptor, a small amount of the receptor is in the active conformation. D) Receptors are chiral. E) Any conformational change of the receptor will cause a message to be sent.
- Which term best applies to the amount of drug required to produce a defined biological effect?
A) Potency B) IC 50 C) Affinity D) Efficacy E) Stability
- An agonist contains an alcohol, an amine, and an aromatic ring, all of which bind to the receptor. Which of the following modifications is most likely to result in an antagonist?
A) Converting the alcohol to a methyl ether B) Adding an extra aromatic ring to the structure C) Synthesizing an analogue which lacks the aromatic ring D) Converting the amine to an amide
- AZT was one of the first drugs approved for the treatment of HIV infections. Based on its chemical structure, it is most likely to be…
A) a chain terminator. B) an alkylating agent. C) an intercalating agent. D) a topoisomerase poison.
- Drugs that are DNA alkylating agents typically…
A) cause themselves to stack between the base pairs. B) stabilize the nicked DNA-topoisomerase complex. C) lead to interstrand or intrastrand crosslinking. D) directly inhibit DNA polymerase.
- SSRI antidepressants work by…
A) binding to, and activating, the serotonin receptor. B) binding to, and inhibiting, the serotonin pump. C) binding to, and deactivating, the serotonin receptor. D) binding to, and inhibiting, the enzyme that makes serotonin.
- Ion-carrier drugs have characteristic structures. They have…
A) a hydrophobic interior and a hydrophobic exterior. B) a hydrophobic interior and a hydrophilic exterior. C) a hydrophilic interior and a hydrophilic exterior. D) a hydrophilic interior and a hydrophobic exterior.
End of multiple-choice section
O
N 3
HO
N
NH
O
O
AZT
- Shown below is the structure of adenosine. Is nitrogen #1 or #2 a better HBA? Explain your reasoning. Your explanation should involve the discussion of electrons and orbitals. (2 marks)
N
N N
N
NH 2
O
OH
HO
- Lactate dehydrogenase as a 1000-fold selectivity for lactate as a substrate over malate. However, if a mutation occurs that alters an active site glutamine residue to an arginine residue, the enzyme shows 10,000-fold selectivity for malate over lactate. Explain this transformation. (1 mark)
NH 2
O
H 2 N
O
OH
glutamine
NH 2
H
N
NH
H 2 N
O
OH
arginine
lactate
COO
OH
malate
COO
OH
OOC
- Why should a transition state be bound more strongly to an enzyme than a substrate or a product? (1 mark)
- The quinazoline structure shown is an inhibitor of the enzyme scytalone dehydratase. One of the binding interactions between the inhibitor and the active site is a hydrogen bond to a water molecule, which acts as a hydrogen-bonding bridge to two tyrosine residues. Explain why analogue 1 is three times less active, whereas analogue 2 is 20 times more active. (1 mark)
N
N
quinazoline
NHR
H
O
H
HO Tyr
HO Tyr
N
analogue 1
NHR
H
N
analogue 2
NHR
CN
- Which one of the following statements is correct? (Question is from the textbook’s website)
A) Drugs and drug targets generally have similar molecular masses. B) Drugs are generally smaller than drug targets. C) Drugs are generally larger than drug targets. D) There is no general rule regarding the relative size of drugs and their targets.
- The hormone adrenaline interacts with proteins located on the surface of cells and does not cross the cell membrane. However, larger steroid molecules, such as estrone, cross cell membranes and interact with proteins located in the cell nucleus. Why is estrone able to cross the cell membrane when a smaller molecule such as adrenaline cannot? (Question is from the textbook)
HO
OH
NH
HO
adrenaline
HO
O
estrone
A) Adrenaline is repelled by the hydrophilic cell membrane. B) Adrenaline has a higher melting point than does estrone. C) Adrenaline is a synthetic drug, and synthetic drugs never cross membranes. D) Estrone is less polar than adrenaline.
- The strongest intermolecular interactions are generally considered to be…
A) hydrophobic interactions. B) covalent bonding. (covalent bonding is not an intermolecular interaction) C) hydrogen bonding. D) dipole-dipole interactions. E) electrostatic interactions.
- Which interaction shown below is most likely to be driven by entropy?
N
O
drug
NH 3
OOC
drug
H
H
drug
drug
A B
C D
O
drug
O
D (hydrophobic “forces” are due to the displacement of water)
- Consider answer A to the question above. The ammonium group in the form shown in the binding site is best described as a…
A) weak base. B) binding group. C) hydrogen bonding acceptor. D) binding region. E) hydrophobic group.
- Shown below is a portion of a polymer made exclusively from the amino acid glycine. The left and right sides of the polymer have been covered up by black boxes. The boxes are not drawn to scale. On which side of the polymer is the N-terminus located?
H
N
N
H
H
N
O
O
left O right
A) Left B) Right (look for an α-carbon and see which side the N is on) C) Cannot be determined from the information given
- Which one of the following statements about a peptide bond is correct?
A) It is not planar. B) It is capable of forming a hydrogen bond. C) The cis configuration is favoured over a trans configuration. D) Single-bond rotation is permitted between nitrogen and the carbonyl group.
- The tertiary structure of a protein is maintained by…
A) intermolecular interactions and intermolecular disulfide linkages. B) intramolecular interactions and intermolecular disulfide linkages. C) intermolecular interactions and intramolecular disulfide linkages. D) intramolecular interactions and intramolecular disulfide linkages.
H 2 N COOH
glycine
- From an energetic standpoint, enzymes can catalyze reactions by…
A) decreasing the energy of the substrate and increasing the energy of the transition state. B) decreasing the energy of the substrate and decreasing the energy of the transition state. C) increasing the energy of the substrate and increasing the energy of the transition state. D) increasing the energy of the substrate and decreasing the energy of the transition state.
- Which one of the following statements best describes an induced fit? (Question is from the textbook’s website)
A) The process by which an active site alters shape such that it is ready to accept a substrate. B) The process by which a substrate adopts the correct binding conformation before entering an active site. C) The process by which a substrate binds to an active site and alters the shape of the active site. D) The process by which an active site alters the shape of the substrate such that it can adopt the necessary active conformation for binding.
- Which one of the following is least likely to act as a source of an acid in the active site of an enzyme?
Side chains: (^) Glu COOH
Asp COOH
Lys
NH 2
His N
NH
A) The side chain of glutamic acid in its neutrally charged form B) The side chain of histidine in its positively charged form C) The side chain of aspartic acid in its neutrally charged form D) The side chain of lysine in its neutrally charged form
- Which statement about receptors is incorrect?
A) Agonists are drugs that have the same effect on a receptor as the endogenous chemical messenger. B) Desensitization occurs when an agonist is bound for a long period of time. C) In the absence of anything bound to a receptor, a small amount of the receptor is in the active conformation. D) Receptors are chiral. E) Any conformational change of the receptor will cause a message to be sent. (must be a correct conformational change)
- Which term best applies to the amount of drug required to produce a defined biological effect? (Question is from the textbook’s website)
A) Potency B) IC 50 C) Affinity D) Efficacy E) Stability
- An agonist contains an alcohol, an amine, and an aromatic ring, all of which bind to the receptor. Which of the following modifications is most likely to result in an antagonist? (Question is from the textbook’s website)
A) Converting the alcohol to a methyl ether B) Adding an extra aromatic ring to the structure C) Synthesizing an analogue which lacks the aromatic ring D) Converting the amine to an amide
- AZT was one of the first drugs approved for the treatment of HIV infections. Based on its chemical structure, it is most likely to be…
A) a chain terminator. (no 3’-OH) B) an alkylating agent. C) an intercalating agent. D) a topoisomerase poison.
- Drugs that are DNA alkylating agents typically…
A) cause themselves to stack between the base pairs. B) stabilize the nicked DNA-topoisomerase complex. C) lead to interstrand or intrastrand crosslinking. D) directly inhibit DNA polymerase.
- SSRI antidepressants work by…
A) binding to, and activating, the serotonin receptor. B) binding to, and inhibiting, the serotonin pump. C) binding to, and deactivating, the serotonin receptor. D) binding to, and inhibiting, the enzyme that makes serotonin.
- Ion-carrier drugs have characteristic structures. They have…
A) a hydrophobic interior and a hydrophobic exterior. B) a hydrophobic interior and a hydrophilic exterior. C) a hydrophilic interior and a hydrophilic exterior. D) a hydrophilic interior and a hydrophobic exterior.
End of multiple-choice section
O
N 3
HO
N
NH
O
O
AZT
