Chemistry 460
First Hour Exam
Name:____________
Please show all work for partial credit
1. (10 points) What do )H, )E, )S, and )G stand for. What are the mathematical and
verbal definitions of these energy functions.
2. )G for the reaction P i + glucose 6 glucose -6-P + H2O = +13.8 kJmol-1
)G for the reaction ATP + H2O 6 ADP + P i = -30.5 kJmol-1
A. (5 points) What is )G for the reaction ATP + Glucose 6 glucose -6-P + ADP?
B. (5 points) Will this reaction be spontaneous?
C. (5 points) What is the K eq for this reaction at 300K? (R= 8.3145 J/mol@K)
3. (5 points) What is the pH of a 4.5x10-3 M solution of NaOH?
2
4A. (5 points) Citric Acid has 3 carboxylic acid functional groups with pKa’s of 3.1, 4.8,
and 6.4 If I wanted to use this to make a buffer solution, at what pH(s) would the solution
make the best buffer?
4B (8 points) If I used 5 g of citric acid, how many grams of NaOH would I need to add to
make a buffer at pH 3.5? (MW citric acid = 192, MW NaOH = 40)
5. (12 points) Fill in the following table
AA Name
Isoleucine
3 letter
Code
1 letter
Code
H
pKa’s
Structure
(pH7)
NH2 +
NH2
CH
NH
CH2
CH2
CH2
NH4+
C
H
COO -
3
4
6. (10 points) Predict the peptides obtained when the following polypeptide is cleaved by
A. Trypsin
B. Elastase
C. CNBr
D. Phenyliosthiocyanate (followed by HCl)
E. Hemoglobin
(Use N.R. for no reaction)
Peptide: nh2 -K-A-A-W-G-K-V-G-A-H-A-G-E-Y-G-A-E-A-L-E-R-M-F-L-S-F-P-T-T-cooh
A.
B.
C.
D.
E.
7. (10 points) Describe, in as much detail as possible, the differences in the helical
structure of collagen and the helical structure of "-keratin
5
8. (10 points) Sodium dodecyl sulfate and urea are common denaturants and their effects
can usually be easily reversed by dialysis. Heat is another way of denaturing proteins, but
its effects are usually not reversible. Please explain why.
9. (10 points) Protein structures can be perturbed by mutations. In some cases these
mutations have little effect and are ‘silent’ in other cases the mutation can completely
change a protein’s structure. How big a change to you think the following mutations will
have in a protein’s structure and why? (Hint, think about the structural difference between
the pairs of amino acids)
Leu6Ile
Lys6Glu
Gly6Ala (in collagen)
Any AA6Pro (in a helix)
Asn6Gln
6