MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED
GUIDE.
Is the dipeptide soluble in water (base your answer on the properties of the side chains, not the NH3+
and CO2- groups on the ends of the dipeptide)?
No
Which level of protein structure relies exclusively on interactions between peptide groups?
Secondary
Where would you expect to find a dipeptide with R groups (side chains), in the cell?
Cytoplasm
Sickle cell anemia is caused by a mutation in the gene encoding Beta-globin. This mutation causes a
glutamic
acid to be changed to a valine. When this change occurs an amino acid with a
(hydrophilic/hydrophobic) side chain is changed to an amino acid with a (hydrophilic/hydrophobic)
side chain.
hydrophilic, hydrophobic
The hemoglobin proteins in individuals with sickle cell anemia tend to aggregate in the red blood cells
causing
those cells to sickle. This is an example of a single change in the primary structure of a polypeptide
altering
other levels of protein structure. Imagine that another mutation occurs in the B globin gene that
changes that
same glutamic acid to an isoleucine. This mutation interrupts the alpha helix formation in the beta
globin gene.
What other levels of protein structure are altered?
Secondary, Tertiary, Quaternary
Altered structures = ?
Altered Functions
The alpha globin polypeptide is found in what protein?
Hemoglobin
You have a patient who is experiencing anemia and excessive fatigue. You take a blood sample from
the
patient and the lab results indicate that the patient has abnormally shaped red blood cells and that
the alpha
globin protein gene has a mutation in the middle of the gene causing a deletion of 10 amino acids.
This protein is found in the cytoplasm of red blood cells. Which statement(s) below is true of alpha
, globin (select all that apply)?
a) All of the side chains on the amino acids in alpha globin must be either polar or charged.
b) Alpha globin is a protein subunit and when misfolded, impacts the overall function of that protein.
c) The side chains hydrogen bond with the peptide groups causing the formation of the alpha helical
regions.
d) The tertiary structure of alpha globin is dependent on its primary sequence.
e) The quaternary structure of hemoglobin is dependent on the primary structure of the alpha and
beta
subunits.
b, d, e
What part of the energy diagram is altered by the presence of an enzyme?
The peak
Which of the following statements apply to enzyme action?
a) Enzymes speed up reactions by altering the overall ∆G of the reaction.
b) Enzymes can be inactivated by temperature or pH changes.
c) The majority of feedback inhibition is regulated by competitive inhibitors.
d) Allosteric inhibitors bind at the active site of the enzyme and prevent the substrate from binding.
b
What property of an enzyme is changed when bound by an allosteric effector (select 1)?
a) the tertiary structure of the enzyme
b) the shape of the active site
c) the amount of product produced
d) all these choices are correct
e
What property of an enzyme is changed when bound by a competitive inhibitor (select one)?
a) the tertiary structure of the enzyme
b) the shape of the active site
c) the amount of product produced
d) all these choices are correct
c
Change in structure = ?
Change in Function
Below is a short single stranded nucleic acid
5' GGCCATACCA-3'
Which nucleotide in the sequence above has a free phosphate group? (A/T/G/C/U)
G
GUIDE.
Is the dipeptide soluble in water (base your answer on the properties of the side chains, not the NH3+
and CO2- groups on the ends of the dipeptide)?
No
Which level of protein structure relies exclusively on interactions between peptide groups?
Secondary
Where would you expect to find a dipeptide with R groups (side chains), in the cell?
Cytoplasm
Sickle cell anemia is caused by a mutation in the gene encoding Beta-globin. This mutation causes a
glutamic
acid to be changed to a valine. When this change occurs an amino acid with a
(hydrophilic/hydrophobic) side chain is changed to an amino acid with a (hydrophilic/hydrophobic)
side chain.
hydrophilic, hydrophobic
The hemoglobin proteins in individuals with sickle cell anemia tend to aggregate in the red blood cells
causing
those cells to sickle. This is an example of a single change in the primary structure of a polypeptide
altering
other levels of protein structure. Imagine that another mutation occurs in the B globin gene that
changes that
same glutamic acid to an isoleucine. This mutation interrupts the alpha helix formation in the beta
globin gene.
What other levels of protein structure are altered?
Secondary, Tertiary, Quaternary
Altered structures = ?
Altered Functions
The alpha globin polypeptide is found in what protein?
Hemoglobin
You have a patient who is experiencing anemia and excessive fatigue. You take a blood sample from
the
patient and the lab results indicate that the patient has abnormally shaped red blood cells and that
the alpha
globin protein gene has a mutation in the middle of the gene causing a deletion of 10 amino acids.
This protein is found in the cytoplasm of red blood cells. Which statement(s) below is true of alpha
, globin (select all that apply)?
a) All of the side chains on the amino acids in alpha globin must be either polar or charged.
b) Alpha globin is a protein subunit and when misfolded, impacts the overall function of that protein.
c) The side chains hydrogen bond with the peptide groups causing the formation of the alpha helical
regions.
d) The tertiary structure of alpha globin is dependent on its primary sequence.
e) The quaternary structure of hemoglobin is dependent on the primary structure of the alpha and
beta
subunits.
b, d, e
What part of the energy diagram is altered by the presence of an enzyme?
The peak
Which of the following statements apply to enzyme action?
a) Enzymes speed up reactions by altering the overall ∆G of the reaction.
b) Enzymes can be inactivated by temperature or pH changes.
c) The majority of feedback inhibition is regulated by competitive inhibitors.
d) Allosteric inhibitors bind at the active site of the enzyme and prevent the substrate from binding.
b
What property of an enzyme is changed when bound by an allosteric effector (select 1)?
a) the tertiary structure of the enzyme
b) the shape of the active site
c) the amount of product produced
d) all these choices are correct
e
What property of an enzyme is changed when bound by a competitive inhibitor (select one)?
a) the tertiary structure of the enzyme
b) the shape of the active site
c) the amount of product produced
d) all these choices are correct
c
Change in structure = ?
Change in Function
Below is a short single stranded nucleic acid
5' GGCCATACCA-3'
Which nucleotide in the sequence above has a free phosphate group? (A/T/G/C/U)
G
