Download 1 Biology 205 Exam 1 4/21/16 1. Geography quiz

Biology 205
Exam 1
4/21/16
1. Geography quiz - Where in the eukaryotic cell would you find the following (Provide the most specific
location. For example, cytochrome oxidase is found in the inner membrane of the mitochondria. An
answer of mitochondria is too general.): (10 pts)
a. Krebs Cycle
b. gluconeogenesis
c. cytochrome C
d. provirus
e. kinesin
f. chaperones
g. pyrimidine
h. chitin
i. heat shock proteins
j. rRNA
2. The structures of the 4 nitrogenous bases found in DNA are provided below. What type of bond allows the
nitrogenous bases to pair? Use these structures to draw how these nitrogenous bases pair in DNA. You do
not need to draw any other part of DNA except the base pairing of the bases listed below. (8 pts)
3. Draw a single strand of DNA containing two complete nucleotides. Identify the phosphodiester bond and
N-glycosidic bond. You do not need to draw the nitrogenous base structures. Simple indicate where the
bases fits into your diagram. (8 pts).
4. Sickle cell anemia results from a single amino acid substitution of a valine for a glutamic acid in the primary
sequence of hemoglobin. What would you expect the effect might be if the mutation were to have a leucine
at the site? What if an aspartic acid were at the site of the mutation? Be sure to explain your answer in
terms of protein structure (1o, 2o, 3 o 4 o). The R groups of valine and leucine are listed below. Be specific.
(8 pts)
valine
leucine
5. What is a temperate phage (virus)? Explain the life cycle of a temperate phage. E. coli infected with a 
provirus (lambda, a temperate phage) can be induced to form progeny viruses by exposure to temperature
above 42°C. Heat stress induces E. coli to produce a protease protein that destroys a repressor protein made
by the  virus that keeps the provirus genome unexpressed. Destruction of the repressor allows the virus to
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go through its lytic cycle. Why would E. coli produce a protease that allows the virus to go lytic which
results in E. coli’s death? Explain your answer. Be specific. (9 pts)
6. Kinases and phosphatases function as switches that can activate or inactivate enzymes. Explain how they
work and how they differ. Explain the catalytic mechanism of each enzyme. You may use diagrams to help
with your explanation. Be specific. (10 pts)
7. A mutation in a particular enzyme causes the enzyme to form more hydrogen bonds with its substrate.
What effect do you think this might have on the enzyme’s function? Start your answer by defining KM,
Vmax and turnover number and then answer the question in terms of KM, Vmax and turnover number. Be
specific. (9 pts)
8. Using your understanding of thermodynamics, explain why non-polar molecules do not readily dissolve in
water. Be sure to define your terms and be specific. (8 pts)
9. The glycolytic pathway is shown below. Add all reactants and products not listed for each step. Clearly
identify which step(s) are substrate level phosphorylation(s) and which step(s) are irreversible. Identify the
steps that are catalyzed by isomerases and mutases. HINT: There are 15 total responses. (15 pts.)
10. In lab, we worked with cytochrome c oxidase. Write the specific reaction that cytochrome c oxidase
catalyzes. (6 pts)
11. You have isolated two mitochondrial fractions (1 & 2) from a sucrose gradient and you are trying to
determine the purity of each isolated fraction. You run a Lowry assay and determine that fraction 1 has a
concentration of 2.2 mg/mL and fraction 2 is 1.3 mg/mL. The cytochrome oxidase (CO) enzyme assay rate
(slope) for fraction 1 was -0.004 absorbance units/min when 0.5 mL of the fraction was used. The CO
enzyme assay rate for fraction 2 was -0.002 absorbance units/min when 0.2 mL of the fraction was used.
Define specific activity. Calculate the specific activity of each fraction and determine which fraction is
more pure. Use the back of this page if you need more space. (9 pts)
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