Cell Chemistry 1. (10 pts.) Matching

a. charged amino acid b. polysaccharide c. glucose

d. DNA e. phospholipid f. uncharged amino acid

g. steroid h. nucleotide i. water

Choose all answers that apply. Each letter may be used more than once or not at all.

__________________________ a polar molecule

___________________________ may be linked together by a phosphodiester bond

___________________________ an amphipathic molecule

___________________________ a hydrophobic molecule

___________________________ can be a monomer for a macromolecule

2. (8 pts.) Below are diagrammed 4 pairs of amino acids. For each pair write whether their interaction will be ATTRACTION, REPULSION or NEITHER.

NO PICTURE but you can look up the amino acids yourself

Pair 1 was: glutamic acid and aspartic acid

Pair 2 was: arginine and valine

Pair 3 was: aspartic acid and lysine

Pair 4 was: valine and proline

DG°' = - RT ln K'eq---------------- The "D" here stands for delta

Thermodynamics 3. (15 pts.) The hydrolysis of succinyl-S-CoA is catalyzed by the enzyme succinyl-CoA synthetase. The DG°' at 25° C for this reaction is -0.7 kcal/mole at 25° C.

succinyl-S-CoA + Pi + GDP -------------------------> succinate + GTP + CoA-SH

a. Is this reaction spontaneous under standard conditions? ____________________________

b. What is the DG' at 25°C for this reaction if: [succinyl-S-CoA] = 1 mM, [succinate] = 5 mM, [CoA-SH] = 3 mM, [Pi] = 2 mM and the ratio of GTP/GDP = 10?

Is the reaction spontaneous under these conditions? _____________________________

c. What ratio of [GTP]/[GDP} would ensure that the reaction is thermodynamically spontaneous using the above concentrations of all other reagents?

d. Hydrolysis of GTP has a DG' at 25° C of -7 kcal/mol. GTP + H2O ------------> GDP + Pi Write an overall reaction for coupling the hydrolysis of GTP with the hydrolysis of succinyl-S-CoA and calculate the overall DG' at 25° C assuming the concentrations given in part (b).

Enzymes

4. a. (4 pts.) Below is a Lineweaver-Burk double reciprocal plot generated from data on the enzyme studyase (it helps you stay awake while studying). From this plot, determine the Km and the Vmax (remember the correct units!).

Km = _____________________ Vmax = _________________________

b. (2 pts.) Sleepase is another enzyme which uses the same substrate as studyase but has a Km of 20 mM and a Vmax of 15 mmole/min. On the plot above, graph the line for sleepase.

c. (3 pts.) A competitive inhibitor of studyase is added to the reaction. Will the Km for studyase become (LOWER, HIGHER or stay the SAME)?

______________________________________________

d. (3 pts.) Caffeine acts as an allosteric activator of studyase but not sleepase. Will the Vmax for studyase become HIGHER, LOWER or STAY the SAME when caffeine is added to the reaction?

________________________________________________

Metabolism 5. (4 pts.) When the phosphate bonds of ATP are broken a large amount of free energy is liberated. Two properties of ATP that make this possible are

______________________________________________ and

__________________________________________________.

6. (14 points) Use the diagram below to answer the following questions.

The diagram here was the TCA cycle from your book - you can look this up yourself.

a. For each Acetyl-CoA, how many reduced coenzyme molecules are generated? ____________________

b. For each Acetyl-CoA, how many oxidized coenzyme molecules are generated? _____________________

c. Starting with Acetyl-CoA, fill in the NET equation below giving the name and number of all of the starting materials and the products for one complete turn of the cycle. (Do not include coenzymes!)

________________________ + 1 Acetyl-CoA + ____________________________ +

______________________________

______________________________ + ______________________________

THE DIAGRAM HERE WAS THE TCA CYCLE FROM YOUR TEXTBOOK p. 335

7. (8 pts.) Using the diagram of the mitochondria below, choose the letter that corresponds to the location of each of the following:

a. High concentration of H+ ions __________ b. Electron transport proteins are here ________________

c. TCA cycle takes place here ___________ d. ATP generating protein complex is here _____________

HERE WAS A DIAGRAM OF A MITOCHONDRION

A - DESIGNATED INNER MEMBRANE

B - DESIGNATED OUTER MEMBRANE

C - DESIGNATED INNER MEMBRANE SPACE

D - DESIGNATED MATRIX

a. The "powerhouse" of the cell, generates ATP _______________________________________________

b. Converts solar energy into bond energy ___________________________________________________

c. Can be the site of protein synthesis _______________________________________________________

d. Provides cell structure _________________________________________________________________

e. DNA is located here ___________________________________________________________________

8 pts.) In each part, of the two choices, place a check mark next to the one with the higher transition temperature, (assuming a constant temperature).

a. ____________ 40% of the fatty acid chains are unsaturated, all are 18 carbons long

____________ 85% of the fatty acid chains are saturated, all are 18 carbons long

b. ____________ 25% of the fatty acid chains have 16 carbons and 75% have 22 carbons

____________ 45% of the fatty acid chains have 16 carbons and 55% have 22 carbons

c. ____________ there is a protein:lipid ratio of 3.3, all lipids are fully saturated 18 carbons

____________ there is a protein:lipid ratio of 1.6, all lipids are fully saturated 18 carbons

d. ____________ all of the fatty acid chains have 18 carbons plus 2 % cholesterol

____________ all of the fatty acid chains have 18 carbons plus 7% cholesterol