Download Answer key – PracticeExam1

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1. Which are common characteristics of all cell types
a.
b.
c.
d.
e.
They all have a nucleus
They all use the same genetic information
They are all enclosed by a membrane
A and B
B and C
2. What type of bonds is it possible to find in a fatty acid?
a. Peptide bonds
b. Glycosidic linkages
c. Phosphodiester linkages
d. Ester linkages
e. Ionic bonds
3. If the pH of a solution is 4, what is the [OH-] in the solution?
a. 10-1
b. 10-5
c. 10-8
d. 10-10
e. 10-14
4. If the [H+] in the blood increases, the carbonic acid/bicarbonate buffer equilibrium will
result in
a. Increased formation of H2CO3
b. Increased formation of HCO3c. Increased formation of both H2CO3 and HCO3d. Both H2CO3 and HCO3 will be reduced
e. The equilibrium in the buffer dissociation reaction does not change
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Use the figure below to answer Question 6
A
B
C
D
E
6. Which functional group is a weak acid? (C)
7. Hydrogenated fats are a product of an industrial process that adds hydrogen atoms to
vegetable oils which causes the oil to become solid at room temperature. This partially
hydrogenated oil have a longer shelf life. Given what we have learned about fats, select
the correct statement:
a. Saturated fats tend to be more liquid and can reduce “bad cholesterol” levels in
blood as part of a healthy diet.
b. Saturated fats are mainly of animal origin and tend to be solid at room
temperature
c. During the process of hydrogenation, fats become unsaturated
d. Trans fats are healthy and should be part of a healthy diet
e. Saturated fats have more kinks in their tails and it is recommended to incorporate
them in our diets.
8. The function of a protein depends critically on its conformation. There are multiple
levels of structural organization and all of them contributes to the final 3D shape of a
protein. At what level(s) of organization is it possible to find hydrogen bonds
contributing to stabilizing protein structure?
a. Primary and secondary
b. Secondary
c. Primary, Secondary and Tertiary
d. Tertiary
e. Secondary and tertiary
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9. Protein ubiquination is an important cellular mechanism that is involved in which of the
following:
a. Protein tagging and transport to chaperones
b. Protein tagging and transport to proteasomes
c. Protein tagging for nuclear export and import
d. Protein tagging for membrane transport
e. Protein tagging and transport to lysosomes
10. We studied a mutation that cause sickle cell anemia and affects the 3D conformation of
ß-globin leading to abnormal assembly of hemoglobin molecules and dramatic changes in
red blood cell morphology. The mutation in ß-globin leads to:
a. Abnormal interaction between hydrophobic regions exposed in mutant ß-globin
and α-globin molecules
b. Abnormal assembly of hemoglobin molecules
c. Abnormal folding of the tertiary structure of both ß-globin and α-globin
molecules
d. A and B
e. A, B and C
11. DNA and RNA are both polymers of nucleotides. However there are important structural
and functional differences between the two molecules. Which of the following
statements is/are correct:
a. In both DNA and RNA molecules the nitrogen bases form complementary base
pairs by hydrogen bonding
b. The pentose sugar is different in DNA and RNA nucleotides
c. There is one phosphate group in RNA nucleotides and two phosphate groups in
DNA nucleotides
d. There is a 5’ end in DNA but not in RNA polynucleotides
e. A and B
12. Which of these fundamental processes related with the flow of information in the cell
occur in the nucleus:
a. Synthesis of ribosomal proteins
b. Synthesis of nuclear lamina proteins
c. Transcription
d. mRNA and rRNA synthesis
e. C and D
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13. Maraviroc, a drug approved in 2007 to treat HIV infection blocks the CCR5 receptor.
Which of the following statements is true with respect to HIV infection in human cells:
a. The HIV virus uses both CD4 receptor and CCR5 co-receptor to enter into human
cells
b. Some individuals who are resistant to HIV infection carry mutations in the CCR5
co-receptor that block the localization of the receptor in the cell surface
c. Both CD4 receptor and CCR5 co-receptor are also present in the surface of the
HIV virus
d. A and B
e. A, B and C
14. In co-transport mechanisms, animal cells use the gradient of sodium ions that is generated
by the sodium/potassium pumps to drive the active transport of glucose into the cell.
Which of the following would happen if the function of the sodium/potassium pump is
blocked by a poison?
a. The sodium/potassium pump will operate in the opposite direction
b. The concentration of sodium ions will decrease inside the cell
c. Glucose will still enter the cell using the co-transporter
d. The membrane potential will eventually drop
15. Motor neurons localized in the spinal cord are characterized by very long axonal
processes that make synaptic connections with muscle and control movement. How
might mutations in the motor protein dynein affect the function of motor neurons?
a. Dynein mutations would impair the transport of synaptic vesicles from synaptic
terminals to the cell body.
b. Dynein mutations will impair the transport of synaptic vesicles from the cell body
to the synaptic terminals.
c. Dynein mutations will interfere with the assembly of microtubules in the axons of
motor neurons
d. Dynein mutations will interfere with the assembly of microfilaments in motor
neurons
e. A and B
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Practice short answer questions-
1. Familial hypercholesterolemia (FH) is an inherited disorder that leads to aggressive and
premature cardiovascular disease. This includes problems like heart attacks, strokes and
narrowing of the heart valves. For individuals with FH, although diet and lifestyle are
important, they are not the cause of high LDL. Explain in a sentence how inherited
mutations in LDL receptors lead to hypercholesterolemia.
Lecture 6. Mutations in LDL receptors prevent the LDL-cholesterol complex from being
internalized and as a consequence there is an increase of cholesterol deposits in blood
vessels.
2. Explain in a short sentence what is the property of cohesion of water molecules
Lecture 2. Cohesion is originated by the formation of hydrogen bonds between water
molecules that allow for the high surface tension of water and also, capillary movement
of water in plants.
3. Explain in a short sentence what is the structure and the main functions of the golgi
apparatus
Lecture 8. The Golgi apparatus is composed by a stack of membranes with an internal
space called lumen. It has a cis- face close to the rER and a trans- face from where
vesicles bud off. The main functions of the Golgi include protein posttranslational
modification –phosphorylation, glycosylation, etc-, synthesis of polysaccharides and
modification of phospholipids.
4. Explain in a short sentence the four steps involved in tyrosine kinase receptor signaling
Lecture 9. A signal molecule, usually a growth factor, binds to the receptor causing the
receptor to dimerize. Phosphate groups are added via phosphorylation on each of the 6
tyrosine sites activating the receptor. Once the receptor is activated, relay proteins bind
to the receptor and initiate the signal transduction cascade.