MCB 450 Exam 1: Questions and Answers with
Complete Solutions – 2026 Update
1. Describe a peptide bond and its planar interactions - ANSWER -has a partial
double bond between the carbon and Nitrogen
-rigid and planar
-transconfiguration
-uncharged but polar
2. What are the four levels of protein structure? - ANSWER -primary: aa
sequence
- secondary: alpha helix or beta pleated sheets
- tertiary 3-D folding pattern
-quatenary - subunits assemble * not all proteins have
3. Why is proline an alpha helix breaker - ANSWER the side chain is bonded
to both the alpha carbon and the Nitrogen atom which limits the rotation and
reduces flexibility within the polypeptide regions
4. What are the driving forces in protein folding - ANSWER covalent and
noncovalent interactions between side chains
5. What cause protein denaturation? - ANSWER heat - breaks H bonds
low/high pH - disrupts salt bridges and electrostatic repulsion
urea - blocks H bonding and interferes with hydrophobic interactions
6. What is a disulfide bond? - ANSWER a covalent bond between two sulfur
atoms of two amino acids (strong)
7. What is the difference between cysteine and cystine? - ANSWER Cysteine -
high solubility (one molecule) cystine - low solubility (2 molecules)
8. Amyloidosis - ANSWER -general term for diseases in which a protein
becomes misfolded and insoluable due to a mutation or error in post-
translational processing
-results in the formation of protein aggrgates or tangles called amyloid fibrils
or plaques usually adapt a beta pleated sheet structure
1
,9. sickle cell disease - ANSWER beta globin gene mutation that subsitutes
vlaine (hydrophobic) for glutamate (polar)
10.How is pepsinogen activated? What is the role of pepsin in protein
digestion? - ANSWER pepsinogen is activated by the low pH caused by HCl
in the stomach pepsin is a protease and cleaves proteins
11.What is the role of HCl in protein digestion - ANSWER -low pH disrupts
salt bridges and electrostatic repulsion
-activates pepsin
12.Biomolecules can be divided into four different classes. Which of the
following is NOT a major class of biomolecule? - ANSWER Fatty Acids
13.Which of the following molecules are the major components of the
collagen? - ANSWER proteins
14.Water is said to be highly cohesive because water molecules interact with
one another through: - ANSWER hydrogen bonds
15.Which of the following is considered a noncovalent bond? - ANSWER -
electrostatic interactions
-hydrogen bonds
-Van der Waals interactions
-ALL OF THE ABOVE
16.What is the [A-]/[HA] ratio when the weak acid is in a solution two pH units
above its pKa? - ANSWER 100:1
17.Brownian motion is due to: - ANSWER The random fluctuation of the
energy content of the environment and thermal noise
18.Consider a biochemical reaction that is taking place in a 0.1 M buffer. The
initial pH is 7.4, and the pKa of the buffer is 7.2. If, in a final reaction
volume of 1.0 mL, 10 micromol of protons are generated, what would be the
final pH of the solution? - ANSWER 7.22
19.Solution X is at a pH of 3; solution Y is at a pH of 8. Which of the following
statements is TRUE? - ANSWER solution X contains more protons than
solution Y
2
,20.What are the primary chemical components present in a phosphate buffer at
pH 7.4? - ANSWER H₂PO₄⁻ and HPO₄ ⁻²
21.Which of the following characterize α-helix regions of proteins? - ANSWER
They are formed principally by hydrogen bonds between a carbonyl oxygen
atom in one peptide bond and the amide hydrogen from a different peptide
bond.
22.Autopsies of patients with Alzheimer disease show protein aggregates called
neurofibrillary tangles and neuritic plaques in various regions of the brain.
These plaques exhibit the characteristic staining of amyloid. Which of the
following structural features is the most likely characteristic of at least one
protein in these plaques? - ANSWER A high content of beta pleated sheet
structure
23.Which of the following secondary structures is most likely to be found in a
membrane-embedded portion of a protein? - ANSWER an alpha helix
composed entirely of hydrophobic residues
24.Which of the following statements regarding peptide bonds is least accurate?
- ANSWER favored conformation of peptide bonds is with the sequential
alpha carbons in the cis position
25.Which is an appropriate statement of involvement of the hydrophobic effect
in protein folding? - ANSWER Nonpolar portions of the molecule associate
with one another in the interior of the protein.
26.All of the following would disrupt quaternary structure except: - ANSWER
Treat with ascorbic acid (vitamin C).
27.The process of digestion in the stomach is carried out in two main ways.
One way involves the _____environment that exists in the stomach. -
ANSWER low pH
28.The pancreas releases _________ to buffer the pH of the stomach juices. -
ANSWER NaHCO3
29.Pepsin requires _________ to achieve activity. - ANSWER -zymogen
activation
3
, -low pH
-Partial denaturation of protein
30.The result of lipase activity in digestion is: - ANSWER Monoacylgycerol
and two free fatty acids.
31._____ are molecules that aid in lipid adsorption. They are synthesized from
cholesterol in the liver and secreted from the _____. - ANSWER bile salts;
gall bladder
32.What do micelles and chylomicrons have in common? - ANSWER they both
contain fatty acids
33.Many adults are unable to metabolize the milk and experience
gastrointestinal disturbances (diarrhea) if they drink milk. This clinical
symptom is most probably due to a deficiency in: - ANSWER lactase
34.Chylomicrons are: - ANSWER lipoprotein transport particles
35.Which of the following is a complex carbohydrate? - ANSWER both starch
and glycogen
36.What is the concentration of acetic acid in 250 ml of a 100 mM acetate
buffer at pH 4.76? - ANSWER 50 mM
37.Which of the following amino acids has a relatively uncharged side chain
under physiological conditions?
a. Arginine
b. Aspartate
c. Glutamate
d. Lysine
e. Histidine - ANSWER Histidine
38.Which of the following best describes the arrangement of amino acid side
chains in an alpha helix?
a.The side chains point outward away from the helical axis.
b. The side chains point inward toward the center of the helix.
c. The side chains point toward the N-terminal end of the helix.
d. The side chains point toward the C-terminal end of the helix.
4
Complete Solutions – 2026 Update
1. Describe a peptide bond and its planar interactions - ANSWER -has a partial
double bond between the carbon and Nitrogen
-rigid and planar
-transconfiguration
-uncharged but polar
2. What are the four levels of protein structure? - ANSWER -primary: aa
sequence
- secondary: alpha helix or beta pleated sheets
- tertiary 3-D folding pattern
-quatenary - subunits assemble * not all proteins have
3. Why is proline an alpha helix breaker - ANSWER the side chain is bonded
to both the alpha carbon and the Nitrogen atom which limits the rotation and
reduces flexibility within the polypeptide regions
4. What are the driving forces in protein folding - ANSWER covalent and
noncovalent interactions between side chains
5. What cause protein denaturation? - ANSWER heat - breaks H bonds
low/high pH - disrupts salt bridges and electrostatic repulsion
urea - blocks H bonding and interferes with hydrophobic interactions
6. What is a disulfide bond? - ANSWER a covalent bond between two sulfur
atoms of two amino acids (strong)
7. What is the difference between cysteine and cystine? - ANSWER Cysteine -
high solubility (one molecule) cystine - low solubility (2 molecules)
8. Amyloidosis - ANSWER -general term for diseases in which a protein
becomes misfolded and insoluable due to a mutation or error in post-
translational processing
-results in the formation of protein aggrgates or tangles called amyloid fibrils
or plaques usually adapt a beta pleated sheet structure
1
,9. sickle cell disease - ANSWER beta globin gene mutation that subsitutes
vlaine (hydrophobic) for glutamate (polar)
10.How is pepsinogen activated? What is the role of pepsin in protein
digestion? - ANSWER pepsinogen is activated by the low pH caused by HCl
in the stomach pepsin is a protease and cleaves proteins
11.What is the role of HCl in protein digestion - ANSWER -low pH disrupts
salt bridges and electrostatic repulsion
-activates pepsin
12.Biomolecules can be divided into four different classes. Which of the
following is NOT a major class of biomolecule? - ANSWER Fatty Acids
13.Which of the following molecules are the major components of the
collagen? - ANSWER proteins
14.Water is said to be highly cohesive because water molecules interact with
one another through: - ANSWER hydrogen bonds
15.Which of the following is considered a noncovalent bond? - ANSWER -
electrostatic interactions
-hydrogen bonds
-Van der Waals interactions
-ALL OF THE ABOVE
16.What is the [A-]/[HA] ratio when the weak acid is in a solution two pH units
above its pKa? - ANSWER 100:1
17.Brownian motion is due to: - ANSWER The random fluctuation of the
energy content of the environment and thermal noise
18.Consider a biochemical reaction that is taking place in a 0.1 M buffer. The
initial pH is 7.4, and the pKa of the buffer is 7.2. If, in a final reaction
volume of 1.0 mL, 10 micromol of protons are generated, what would be the
final pH of the solution? - ANSWER 7.22
19.Solution X is at a pH of 3; solution Y is at a pH of 8. Which of the following
statements is TRUE? - ANSWER solution X contains more protons than
solution Y
2
,20.What are the primary chemical components present in a phosphate buffer at
pH 7.4? - ANSWER H₂PO₄⁻ and HPO₄ ⁻²
21.Which of the following characterize α-helix regions of proteins? - ANSWER
They are formed principally by hydrogen bonds between a carbonyl oxygen
atom in one peptide bond and the amide hydrogen from a different peptide
bond.
22.Autopsies of patients with Alzheimer disease show protein aggregates called
neurofibrillary tangles and neuritic plaques in various regions of the brain.
These plaques exhibit the characteristic staining of amyloid. Which of the
following structural features is the most likely characteristic of at least one
protein in these plaques? - ANSWER A high content of beta pleated sheet
structure
23.Which of the following secondary structures is most likely to be found in a
membrane-embedded portion of a protein? - ANSWER an alpha helix
composed entirely of hydrophobic residues
24.Which of the following statements regarding peptide bonds is least accurate?
- ANSWER favored conformation of peptide bonds is with the sequential
alpha carbons in the cis position
25.Which is an appropriate statement of involvement of the hydrophobic effect
in protein folding? - ANSWER Nonpolar portions of the molecule associate
with one another in the interior of the protein.
26.All of the following would disrupt quaternary structure except: - ANSWER
Treat with ascorbic acid (vitamin C).
27.The process of digestion in the stomach is carried out in two main ways.
One way involves the _____environment that exists in the stomach. -
ANSWER low pH
28.The pancreas releases _________ to buffer the pH of the stomach juices. -
ANSWER NaHCO3
29.Pepsin requires _________ to achieve activity. - ANSWER -zymogen
activation
3
, -low pH
-Partial denaturation of protein
30.The result of lipase activity in digestion is: - ANSWER Monoacylgycerol
and two free fatty acids.
31._____ are molecules that aid in lipid adsorption. They are synthesized from
cholesterol in the liver and secreted from the _____. - ANSWER bile salts;
gall bladder
32.What do micelles and chylomicrons have in common? - ANSWER they both
contain fatty acids
33.Many adults are unable to metabolize the milk and experience
gastrointestinal disturbances (diarrhea) if they drink milk. This clinical
symptom is most probably due to a deficiency in: - ANSWER lactase
34.Chylomicrons are: - ANSWER lipoprotein transport particles
35.Which of the following is a complex carbohydrate? - ANSWER both starch
and glycogen
36.What is the concentration of acetic acid in 250 ml of a 100 mM acetate
buffer at pH 4.76? - ANSWER 50 mM
37.Which of the following amino acids has a relatively uncharged side chain
under physiological conditions?
a. Arginine
b. Aspartate
c. Glutamate
d. Lysine
e. Histidine - ANSWER Histidine
38.Which of the following best describes the arrangement of amino acid side
chains in an alpha helix?
a.The side chains point outward away from the helical axis.
b. The side chains point inward toward the center of the helix.
c. The side chains point toward the N-terminal end of the helix.
d. The side chains point toward the C-terminal end of the helix.
4
