BCHM EXM 2 2026 UPDATE QUESTIONS AND
CORRECT VERIFIED ANSWERS ALREADY GRADED
A+
hydrophobic effect - ANS-the exclusion of nonpolar substances from
an aqueous solution
How does the hydrophobic effect impact entropy? - ANS-it increases it
by lowering the number of constrained water molecules
micelle - ANS-lipid molecules that arrange themselves in a
spherical form in aqueous solutions
Why is pH important in living organisms? - ANS-it must be maintained
to maintain the structure and function of other molecules in the
cell
What are protonation states dependent on and why does that matter? -
ANS-protonation states are dependent on pH, which impacts the
functionality of a protein
hydronium ions - ANS-H3O+, formed by the ionization of water
dissociation constant - ANS-K, describes the ionization of water
where H+ and OH- are inversely proportional
What is Kw at 25 degrees C? - ANS-10-14
At equilibrium, what is true about the concentration of OH- and H+ ions? -
ANS-they are equal
,What happens when a strong acid is added to a solution? - ANS-it
completely dissociates and decreases pH
What happens when a weak acid is added to a solution? - ANS-it does
not completely dissociate and will have less of an impact on pH
What does a high Ka indicate? - ANS-a strong acid
What does pKa describe? - ANS-an acids tendency to ionize
What does a lower pK indicate? - ANS-a stronger acid and higher
tendency to ionize
Henderson-Hasselbalch equation - ANS-indicates that when the pH of
a solution of acid is equal to the pK of that acid there are equal
concentrations of acid and base
What happens when pH is less than pK? - ANS-functional groups will
stay protonated
What happens when pH is greater than pK? - ANS-functional groups
will deprotonate
buffer - ANS-weak acid or conjugate base that prevents dramatic
changes in pH
In what pH range are buffers most effective? - ANS-1 above or below
the pKa
How can proteins be distinguished? - ANS-number, composition, and
sequence of amino acid residues
, zwitterion - ANS-a molecule that carries both positive and negative
charge but is overall neutral
What are the charges of an amino acid at neutral pH? - ANS--1 on the
carboxylate and +1 on the amino group
What does is mean that the alpha carbon of amino acids are asymmetric?
- ANS-19/20 alpha carbons are chiral
What is the most common enantiomer of alanine? - ANS-L-alanine
(amino group on the left)
enantiomers - ANS-non-superimposable mirror image
How are amino acids linked? - ANS-by peptide bonds formed on
ribosomes via a dehydration reaction between the carboxylate
and amino group
N-terminus - ANS-has a free ionizable amino group
C-terminus - ANS-has a free ionizable carboxylate group
amino acid residues - ANS-amino acids within a peptide because
only residual atoms remain
oligopeptides (or just peptides) - ANS-~10-30 AA
polypeptides - ANS-~ 100-1000 amino acid residues
What do the electrostatic properties of a polypeptide depend on? - ANS-
the presence of charged side chains (R groups)
CORRECT VERIFIED ANSWERS ALREADY GRADED
A+
hydrophobic effect - ANS-the exclusion of nonpolar substances from
an aqueous solution
How does the hydrophobic effect impact entropy? - ANS-it increases it
by lowering the number of constrained water molecules
micelle - ANS-lipid molecules that arrange themselves in a
spherical form in aqueous solutions
Why is pH important in living organisms? - ANS-it must be maintained
to maintain the structure and function of other molecules in the
cell
What are protonation states dependent on and why does that matter? -
ANS-protonation states are dependent on pH, which impacts the
functionality of a protein
hydronium ions - ANS-H3O+, formed by the ionization of water
dissociation constant - ANS-K, describes the ionization of water
where H+ and OH- are inversely proportional
What is Kw at 25 degrees C? - ANS-10-14
At equilibrium, what is true about the concentration of OH- and H+ ions? -
ANS-they are equal
,What happens when a strong acid is added to a solution? - ANS-it
completely dissociates and decreases pH
What happens when a weak acid is added to a solution? - ANS-it does
not completely dissociate and will have less of an impact on pH
What does a high Ka indicate? - ANS-a strong acid
What does pKa describe? - ANS-an acids tendency to ionize
What does a lower pK indicate? - ANS-a stronger acid and higher
tendency to ionize
Henderson-Hasselbalch equation - ANS-indicates that when the pH of
a solution of acid is equal to the pK of that acid there are equal
concentrations of acid and base
What happens when pH is less than pK? - ANS-functional groups will
stay protonated
What happens when pH is greater than pK? - ANS-functional groups
will deprotonate
buffer - ANS-weak acid or conjugate base that prevents dramatic
changes in pH
In what pH range are buffers most effective? - ANS-1 above or below
the pKa
How can proteins be distinguished? - ANS-number, composition, and
sequence of amino acid residues
, zwitterion - ANS-a molecule that carries both positive and negative
charge but is overall neutral
What are the charges of an amino acid at neutral pH? - ANS--1 on the
carboxylate and +1 on the amino group
What does is mean that the alpha carbon of amino acids are asymmetric?
- ANS-19/20 alpha carbons are chiral
What is the most common enantiomer of alanine? - ANS-L-alanine
(amino group on the left)
enantiomers - ANS-non-superimposable mirror image
How are amino acids linked? - ANS-by peptide bonds formed on
ribosomes via a dehydration reaction between the carboxylate
and amino group
N-terminus - ANS-has a free ionizable amino group
C-terminus - ANS-has a free ionizable carboxylate group
amino acid residues - ANS-amino acids within a peptide because
only residual atoms remain
oligopeptides (or just peptides) - ANS-~10-30 AA
polypeptides - ANS-~ 100-1000 amino acid residues
What do the electrostatic properties of a polypeptide depend on? - ANS-
the presence of charged side chains (R groups)
