BB 350 Exam 1
Name _____________ ID #__________
General Instructions: This exam is worth 100 points total. Read the instructions for
each question carefully. If you do not understand the instructions for a question or what
is being asked in a question, raise your hand. Be careful how you mark your exam. If
graders are uncertain about how any question is answered, it will automatically be
marked incorrect. Do not spend too much time on any one question.
There are 5 pages in this exam, including the cover page.
Scores
Section I (13 points)
________________
Section II (45 points) ________________
Section III (42 points) ________________
Total
________________
Important items
A. The logarithm of a number greater than one is a positive number.
B. The logarithm of a number less than one is a negative number
C. For any number X (except X=0), ln (X) = -ln(1/X)
[or log(x) = -log(1/x)]
D. pH = pKa + log {[Salt]/[Acid]}
E. pH = -log[H+] , pOH = -log[OH-], pKa = -Log[Ka], pH + pOH = 14
BB 350, Spring, 2012. Exam #1, Page 1
Section I: The statements in this section can be completed by any of the lettered
responses following it. Each statement may have more than one answer that is
correct, one answer that is correct, or no answers that are correct. Students should
clearly circle only those responses that complete the sentence to make a correct
statement. Points will be awarded for each circled response that makes a correct
statement and for each uncircled response that makes an incorrect statement. For
example, the practice question below has three correct answers (b,c,d). You would
receive eight points if you circled ‘b’,’c’, and ‘d’. You would receive two points if
you circled ‘a’ and ‘b’. You would receive no points if you circled only ‘a’. If we
have uncertainty about whether or not an answer is marked, it will automatically be
counted as a wrongly answered question. Be clear in your markings.
Practice question #A: Oregon State University
A. is a factory in Portland
B. is located in Corvallis, Oregon
C. has a mascot named Benny Beaver
D. has students from all over the world.
1. With respect to water,
A. hydrogen bonds arise from uneven sharing of electrons
B. it has a lower boiling point than something with no hydrogen bonds
C. molecules that dissolve in it are hydrophilic
D. it facilitates ionization
2. Amino acids
A. all have nitrogen except glycine
B. differ in their composition of R groups
C. are the building blocks of nucleic acids
D. have more than one pI if they have three ionizable groups
3. In protein structure,
A. disulfide bonds hold primary structure together
B. tertiary structure involves alpha helices or beta strands
C. hydrophobic bonds are usually on the inside of proteins
D. ionization can affect protein structure
Section II: 1. Each sentence below in this section is missing a
word or short phrase to complete it. Fill in the blank as
appropriate to complete the sentence with a correct statement.
Each correctly filled in blank below will be awarded three
points. You MUST be precise in your definitions.
1. Describe the structure of the bonds in collagen that stabilize its structure?
________________
BB 350, Spring, 2012. Exam #1, Page 2
2. The blood pH of Oregon Governor John Kitzhaber suddenly rises. What happens to
oxygen release from his hemoglobin? ________________
3. What is the name of the amino acid that makes disulfide bonds? ________________
4. A buffer solution has a fixed amount of salt and acid. A magician waves a wand to
make half of the salt magically disappear. Describe what happens to the pH.
________________
5. At most concentrations of oxygen, which protein described in class holds oxygen most
tightly? ________________
6. How is the term allosterism defined? ________________
7. Describe the beads used in molecular (gel) exclusion chromatography
________________
8. Two enzymes (X & Z) isolated from Russian President, Vladimir Putin catalyze the
same reaction. X has a higher Km. Which enzyme requires less substrate to get to
Vmax/2? ________________
9. You have 600 ml of a 1M buffer in which there is twice as much acid as salt. Is the pH
higher than or lower than the pKa? ________________
10. You have a buffer in your laboratory, but you do not know its pKa. You do know,
however, that you have a solution of it with equal amounts of salt and acid. What one
thing would you do to determine its pKa? ________________
11. Describe how the pKa of a weak acid changes with pH ________________
BB 350, Spring, 2012. Exam #1, Page 3
12. A polypeptide from the forehead of the major puffball, Donald Trump, is discovered
with the following sequence
Leucine-Proline-Lysine-Glycine-Serine-Aspartic acid
pKa values for the various groups in the molecule are as follows:
Alpha carboxyl = 2 / Alpha amino = 9 / R-group amino = 11.3 / R-group carboxyl = 4.8
What is the overall charge of this molecule at pH 7.9? ________________
13. Precisely what does it mean when an enzyme has a Kcat of 500/second?
________________
14. A genetic disease was described in class that may provide protection against another
disease. What is the name of the disease that the genetic disease provides some
protection against? ________________
15. What vitamin is necessary to strengthen collagen? ________________
BB 350, Spring, 2012. Exam #1, Page 4
Section 3 – Problems/Long Answer
In this section, you should ORGANIZE and LABEL any work you do. No partial
credit will be given to unlabeled answers.
1. Hemoglobin carries both oxygen and carbon dioxide in the body of everyone,
including Republican Presidential candidate, Mitt Romney. Explain where in Romney’s
body each molecule is picked up and where it is released. Name all of the items
described in class that affect oxygen’s binding to hemoglobin and where you would find
them (12 points)
2. Three people have the same mixture of proteins that differ in size and charge and they
want to purify them. Person ‘A’ (also known as Vice President Joe Biden) wants to use a
method that separates the molecules on the basis of size where the smallest proteins on
the apparatus move the fastest. Person ‘B’ (also known as OSU President Ed Ray) wants
to use a method that separates on the basis of size where the largest proteins on the
apparatus move the fastest. Person ‘C’ (also known as Spiderman) wants to use a method
where the most positively charged proteins move slower than the most negatively
charged proteins. Name (precisely) the method described in class that each person needs
to use. (12 points total)
Biden
Ray
Spiderman
3. One liter of a buffer from the blood of famous TV dog Lassie (pKa = 4.76) is found to
have 0.4 moles of acid and 0.1 moles of salt.
a. Is the pH of the buffer greater than, equal to, or less than 4.76? Show your reasoning
mathematically. (6 points)
BB 350, Spring, 2012. Exam #1, Page 5
b. You wish to get the buffer to maximum buffering capacity. You have HCl and NaOH
available. Which would you add and how much? Show your reasoning. (8 points)
c. Is the pH of the buffer after step b greater than, equal to, or less than 4.76? (4 points)
BB 350, Spring, 2012. Exam #1, Page 6