ACS BIOCHEMISTRY EXAM | QUESTIONS AND VERIFIED
ANSWERS | LATEST EXAM
Metabolism (catabolism and anabolism) - CORRECT 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 - CORRECT 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.
What accounts for water's unique properties? - CORRECT ANSWER -
Hydrogen bonding
The unique properties of water (specific heat, heat of vaporization, solubility) -
CORRECT 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 - CORRECT 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 - CORRECT ANSWER - pH= -log[H3O+]
pKa= -log(Ka)
Normal blood pH range - CORRECT ANSWER - 7.35-7.45
The Hydrophobic Effect - CORRECT 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.
The aggregation is responsible for the formation of a variety of lipid structures
in the body, including cell membranes.
Buffers - CORRECT 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? - CORRECT
ANSWER - When [HA]= [A-], occurring when pH=pKa
Henderson- Hasselbalch allows use to calculate pH at given pKa, and vice
versa:
Blood Buffering - CORRECT 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 - CORRECT 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!
A long peptide is called a polypeptide!
Proteins are composed of one or more polypeptide chain.
Peptide bonds - CORRECT 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? - CORRECT
ANSWER - 280 nm, with tryptophan absorbing more, tyrosine absorbing a bit
less, and phenylalanine absorbing a lot less.
ANSWERS | LATEST EXAM
Metabolism (catabolism and anabolism) - CORRECT 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 - CORRECT 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.
What accounts for water's unique properties? - CORRECT ANSWER -
Hydrogen bonding
The unique properties of water (specific heat, heat of vaporization, solubility) -
CORRECT 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 - CORRECT 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 - CORRECT ANSWER - pH= -log[H3O+]
pKa= -log(Ka)
Normal blood pH range - CORRECT ANSWER - 7.35-7.45
The Hydrophobic Effect - CORRECT 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.
The aggregation is responsible for the formation of a variety of lipid structures
in the body, including cell membranes.
Buffers - CORRECT 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? - CORRECT
ANSWER - When [HA]= [A-], occurring when pH=pKa
Henderson- Hasselbalch allows use to calculate pH at given pKa, and vice
versa:
Blood Buffering - CORRECT 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 - CORRECT 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!
A long peptide is called a polypeptide!
Proteins are composed of one or more polypeptide chain.
Peptide bonds - CORRECT 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? - CORRECT
ANSWER - 280 nm, with tryptophan absorbing more, tyrosine absorbing a bit
less, and phenylalanine absorbing a lot less.
