UNE Biochemistry Unit 1 TEST UPDATED
ACTUAL Exam Questions and CORRECT
Answers
What is pKa? - CORRECT ANSWER - -logKa (-log saturation limit)
When is a functional group ionized? (with respect to pKa and pH?) - CORRECT
ANSWER - Ionized if pKa is lower than the pH. Protonated if higher than pH.
What is an allosteric activator? - CORRECT ANSWER - Binds to enzyme's active site and
helps to activate
What is an allosteric inhibitor? - CORRECT ANSWER - Binds to enzymes active and
inhibits activation.
Competitive inhibitors? - CORRECT ANSWER - Compete with substrate for binding at
enzyme's substrate recognition site. This increases Km because it increases the concentration of
substrate needed to saturate the enzyme, but no change to Vmax.
Noncompetitive inhibitor - CORRECT ANSWER - Does not compete with substrate for
binding at the enzyme's substrate recognition site. Lowers concentration of active enzyme so
Vmax decreases, but no change to Km.
Ion product of water - CORRECT ANSWER - Kw = [H+][OH-] = 1x10^-14 mol/L
Amino Acid composition (bonds) - CORRECT ANSWER - Central carbon atom
connected to a hydrogen, amino (NH3) group, carboxyl group (COOH), and R group.
In a polypeptide at physiologic pH, hydrogen bonding may occur at: - CORRECT
ANSWER - The amide group in the peptide bond an an aspartyl side chain.
, The following shows the linear sequence of atoms joined by covalent bonds in the peptide
backbone: - CORRECT ANSWER - N-C-C-N-C-C-N-C-C
Different preparations of insulin contain some insulin complexed with protamine that is absorbed
slowly after injection. Protamin is a protein preparation form rainbow trout sperm containing
arginine rich peptides that bond to insulin. What is the best explanation? - CORRECT
ANSWER - Arginine is basic amino acid that binds to negatively charged amino acid side
chains in insulin.
Protein kinases phosphorylate proteins only at a certain hydroxyl groups on amino acid side
chains. All contain side chain hydroxyl groups: - CORRECT ANSWER - Serine,
Threonine, Tyrosine
A protein's activity is altered when a particular serine side chain is phosphorylated (Adds
negative charges to side chain). Which of the following amino acid substitutions at this position
could lead to permanent altercation in normal enzyme activity? - CORRECT ANSWER -
S->E Glutamate = negative charge - acidic
Decrease of blood pH from 7.5 to 6.5 would be accompanied by the following changes in ion
concentration: - CORRECT ANSWER - A 10 fold increase in concentration of H+
If ammonia NH3 is absorbed and enters circulation, what is the consequence? - CORRECT
ANSWER - Ammonia will be converted to NH4+ ammonium ion in the blood. (pka of
ammonia is 9.5 so at physiological ph of 7.4, the ammonia will be present as ammonium ion,
makes blood basic)
Which of the following physiologic/pathological conditions is the most likely to result in
alkalosis, provided that the body could not fully compensate? - CORRECT ANSWER -
Repeated vomiting with loss of HCl
Methylmalonate -OOC-CH(CH3)-COO- - CORRECT ANSWER - Conjugate base of
weak acid
ACTUAL Exam Questions and CORRECT
Answers
What is pKa? - CORRECT ANSWER - -logKa (-log saturation limit)
When is a functional group ionized? (with respect to pKa and pH?) - CORRECT
ANSWER - Ionized if pKa is lower than the pH. Protonated if higher than pH.
What is an allosteric activator? - CORRECT ANSWER - Binds to enzyme's active site and
helps to activate
What is an allosteric inhibitor? - CORRECT ANSWER - Binds to enzymes active and
inhibits activation.
Competitive inhibitors? - CORRECT ANSWER - Compete with substrate for binding at
enzyme's substrate recognition site. This increases Km because it increases the concentration of
substrate needed to saturate the enzyme, but no change to Vmax.
Noncompetitive inhibitor - CORRECT ANSWER - Does not compete with substrate for
binding at the enzyme's substrate recognition site. Lowers concentration of active enzyme so
Vmax decreases, but no change to Km.
Ion product of water - CORRECT ANSWER - Kw = [H+][OH-] = 1x10^-14 mol/L
Amino Acid composition (bonds) - CORRECT ANSWER - Central carbon atom
connected to a hydrogen, amino (NH3) group, carboxyl group (COOH), and R group.
In a polypeptide at physiologic pH, hydrogen bonding may occur at: - CORRECT
ANSWER - The amide group in the peptide bond an an aspartyl side chain.
, The following shows the linear sequence of atoms joined by covalent bonds in the peptide
backbone: - CORRECT ANSWER - N-C-C-N-C-C-N-C-C
Different preparations of insulin contain some insulin complexed with protamine that is absorbed
slowly after injection. Protamin is a protein preparation form rainbow trout sperm containing
arginine rich peptides that bond to insulin. What is the best explanation? - CORRECT
ANSWER - Arginine is basic amino acid that binds to negatively charged amino acid side
chains in insulin.
Protein kinases phosphorylate proteins only at a certain hydroxyl groups on amino acid side
chains. All contain side chain hydroxyl groups: - CORRECT ANSWER - Serine,
Threonine, Tyrosine
A protein's activity is altered when a particular serine side chain is phosphorylated (Adds
negative charges to side chain). Which of the following amino acid substitutions at this position
could lead to permanent altercation in normal enzyme activity? - CORRECT ANSWER -
S->E Glutamate = negative charge - acidic
Decrease of blood pH from 7.5 to 6.5 would be accompanied by the following changes in ion
concentration: - CORRECT ANSWER - A 10 fold increase in concentration of H+
If ammonia NH3 is absorbed and enters circulation, what is the consequence? - CORRECT
ANSWER - Ammonia will be converted to NH4+ ammonium ion in the blood. (pka of
ammonia is 9.5 so at physiological ph of 7.4, the ammonia will be present as ammonium ion,
makes blood basic)
Which of the following physiologic/pathological conditions is the most likely to result in
alkalosis, provided that the body could not fully compensate? - CORRECT ANSWER -
Repeated vomiting with loss of HCl
Methylmalonate -OOC-CH(CH3)-COO- - CORRECT ANSWER - Conjugate base of
weak acid
