©FYNDLAY EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
ACS Biochemistry Exam Questions And
Answers (Guaranteed A+)
Metabolism (catabolism and anabolism) - answer✔Metabolism: sum of total chemical reactions
in an organism, also the method by which cells extract and use energy from their environment.
Catabolism: The process by which stored nutrients and ingested foods are converted to a
usable form of energy. It produces simple products CO2, H2O, NH3, and building blocks such as
sugars and fats that are used in anabolism.
Anabolism: the process by which simple products and building blocks of catabolism are used to
create complex biological products that contribute to organismal growth and development. It
also uses the energy produced in catabolism to do biological work.
Properties of cells - answer✔Metabolism: undergoing catabolic and anabolic processes.
Reproduction: cell populations grow via asexual reproduction.
Mutation: during growth and reproduction, cells sometimes make mistakes, leading to
mutations and evolution.
Respond to environment: metabolic pathways respond to signals, including light, touch,
hormones, and nutrients, that can turn the pathways on or off.
Speed and efficiency: cell operations are highly specific to maximize targeting and efficiency.
Similar building blocks: most species are very similar at the cellular level.
1|Page
, ©FYNDLAY EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
What accounts for water's unique properties? - answer✔Hydrogen bonding
The unique properties of water (specific heat, heat of vaporization, solubility) - answer✔1) high
specific heat, or heat required to raise the temperature of the unit mass of a given substance by
one degree.
For water to increase in temperature, water molecules must be made to move faster, or get
higher KE, and doing this requires breaking hydrogen bonds, which absorbs heat. So, as heat is
applied, most of it goes to breaking the bonds not upregulating KE, thus making water harder to
heat than substances where no bonds need to be broken.
2) High heat of vaporization, or the amount of heat needed to turn one g of a liquid into vapor,
without a temperature rise in the liquid. Important for sweat because it ensures that when the
liquid evaporates from our skin, the heat required for the transition is kept in the gas, causing a
net cooling effect on the skin.
3) Unique solubility properties: "like dissolves like". Water dissolves polar molecules and ions,
and can act as an H-bond donor or receptor
4) Amphoteric, it can act as an acid (donating electrons) or a base (accepting electrons). The
conjugate acid of water is the hydronium ion, H3O+, and the conjugate base of water is the
hydroxide ion, OH-.
Keq for water at 25 degrees C and in pure water - answer✔At 25 degrees C:
Keq= Kw= [OH-][H3O+]= 1*10^-14
In pure water:
[OH-]=[H3O+]= 1*10^-7
Calculation for pH and pKa - answer✔pH= -log[H3O+]
pKa= -log(Ka)
Normal blood pH range - answer✔7.35-7.45
The Hydrophobic Effect - answer✔When non-polar molecules aggregate in the presence of
water, minimizing the entropy decrease water must go through to order themselves around the
border of the non-polar molecule. Reducing the surface area water must organize around
increases entropy, which is favorable.
2|Page
, ©FYNDLAY EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
The aggregation is responsible for the formation of a variety of lipid structures in the body,
including cell membranes.
Buffers - answer✔Composed of a weak acid (HA) and its conjugate base (A-). Added acid reacts
with A-, and added base reacts with HA, giving a limited overall pH change.
Two main reactions:
1) When excess base is added:
OH-+HA-->H2O+A-
2) When excess acid is added:
H+ + A- -->HA
**So, the net result is more of the weak acid and its conjugate base**
When are buffers optimal? What equation can we use for this? - answer✔When [HA]= [A-],
occurring when pH=pKa
Henderson- Hasselbalch allows use to calculate pH at given pKa, and vice versa:
Blood Buffering - answer✔Components:
1) carbonic acid (H2CO3) (weak acid). pKa= 6.1.
2) Bicarbonate Ion (HCO3-), conjugate base of carbonic acid
3) H+ (hydrogen ion)
If OH- (base) is added, Carbonic acid buffers it into bicarbonate ion and water.
If H+ (acid) is added, bicarbonate ions and H+ buffer it to carbonic acid.
Amino Acids, peptides, and polypeptides - answer✔the building blocks of proteins, a chain of
which is called a peptide. There are 20 standard amino acids that act as the monomers to make
protein polymers!
3|Page
, ©FYNDLAY EXAM SOLUTIONS 2024/2025
ALL RIGHTS RESERVED.
A long peptide is called a polypeptide!
Proteins are composed of one or more polypeptide chain.
Peptide bonds - answer✔Between the C and N of C=O and N-H of two adjacent amino acids.
What wavelength is indicative of aromatic amino acids? - answer✔280 nm, with tryptophan
absorbing more, tyrosine absorbing a bit less, and phenylalanine absorbing a lot less.
Stereochemistry of amino acids - answer✔Every carbon except for glycine is a chiral center,
giving two possible structures for each: L and D (except for glycine).
L is the only one found in nature.
Acid-Base properties of amino acids - answer✔Each has at least two ionizable protons (from the
COOH and NH3 groups), but most have others.
COOH pKa: 2.34
NH3 pKa: 29.60
PI - answer✔the isoelectric point, or the pH at which an amino acid or peptide has no net
charge.
- At pH= PI, the predominant species is the zwitterion
- At pH<PI, the predominant species is net positive
- At pH>PI, the predominant species is net negative
**At PI, amino acid or peptide cannot migrate through an electric field, so this is a way we can
separate amino acids (by PI via electric field!)**
How to calculate PI, or isoelectric pint - answer✔Average pKa values involving the neutral
species
4|Page
