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A.   Test #2 Key – Multiple Choice

1.               B

2.               C

3.               B

4.               B

5.               C

6.               B

7.               D

8.               B

9.               B

10.           C

11.           C

12.           B

13.           A

14.           E

15.           B

16.           C

17.           B

18.           C

19.           A

20.           A

Part II: (40 points; 4 sections. 10 points for each section)

 

1. Glycolysis consists of the following 10 reactions:

 

In the margin above, draw the structures of:

1.     fructose-1,6-bisphosphate      See text pg. 148 [2 pts]     

2.     pyruvate            See text pg. 149  [2 pts]

           

The carbon atoms in the carboxyl groups of pyruvate came from carbon

atoms __3___  and ___4_____  in glucose. [1/2 pt each]

 

Aldolase catalyzes reaction __4_____. [1 pt]

 

NADH is formed in reaction(s) ___6____. [1 pt]

 

ATP is consumed in reactions ____1____and____3____ and  produced in reactions

___7___and____10___ . [1/2 pt each]

 

Which reaction is the principal regulated step controlling the flow of

carbohydrate into the pathways of cellular respiration? ____3______ [1 pt]

 

 

2. Citric acid cycle

 

Draw the structure of the missing citric acid cycle intermediate (where the “?” is shown).            See text page 153; alpha keto glutarate  [2 pts]

 

NADH is formed in reactions __3,4,8 [more than 3 subtracts ½ pt  each]__ (list all of them). [1/2 pt each]

 

GTP is formed in reaction(s) ____5_____.[1/2 pt each]

 

CO2  is released in reactions ____3___  and ___4_____.[1/2 pt each]

 

H2O is taken up in reactions ___1_____ and ___7_____.[1/2 pt each]

 

Each acetyl-CoA consumed in the citric acid cycle can produce ___12____

ATP equivalents.  (Include the contributions of each acetyl-CoA breakdown to the electron transport chain and to oxidative phosphorylation in your answer.) [2 pts]

 

Isocitrate dehydrogenase is an allosteric enzyme that is activated by __ADP ; NAD+__  and inhibited by _ATP; NADH_ . [1 pt each blank, only one necessary for each blank]

 

 

 

3. Oxidative phosphorylation

 

Write out the overall reaction (or give the enzymatic name for the reaction) catalyzed by the mitochondrial Complex I.

 

 

NADH + CoEnzyme Q + H  à NAD+ + Reduced CoEnzymeQH2

 

Or

 

NADH-CoQ Reductase

[2 pts]

 

 

Of the 38 ATP produced during cellular respiration in a prokaryotic cell,

 

__34____ of these ATP are produced by oxidative phosphorylation.

[1 pt]

 

Two mobile electron carriers serve to transport electrons between Complexes I, III, and IV.  Name these two substances.

 

Coenzyme Q [Ubiquinone}

Cytochrome c

[1 pt each]

 

In cellular respiration, the oxidation of a glucose molecule to 6 CO2 molecules leads to the reduction of ___10__molecules of NAD+ to NADH.

[1 pt]

 

How does electron transport provide the energy that drives oxidative phosphorylation (in 20 words or less)?  If answer exceeds 40 words, 0 pts.

[4 pts possible]

 

Drives the establishment of H+ gradient across the cristae membrane

Or

Proton motive force

Or

Chemi-osmotic gradient of H+

Or

Pumps H+ across non-permeable membrane to force return through ATP synthase

 

 

4. Photosynthesis

Which of the following processes:

B.    Photosystem I

C.    Photosystem II

D.    Cytochrome b/f complex

E.     Calvin-Benson cycle

 

is most closely associated with:

 

The evolution of O2_______B___________

 

The reduction of NADP+_____A_______________

 

The reduction of CO2_________D______________

 

The oxidation of NADPH_______D_______________

 

The splitting of water____________B_____________

 

[2 Pts each]

 

 

Part III: Essay Questions (20 points  (10 points each)).

1. Describe, using words and diagrams, the pathway of events by which a water-soluble hormone causes an increase in [cAMP]cytosol.

 

2. Describe, using words and diagrams, the structure of the mitochondrial F1F0-ATP synthase and the molecular mechanism by which it taps a chemi-osmotic gradient to drive ATP synthesis.

 

Essay scoring:

 

1.       Water-soluble hormone ® increase in [cAMP]

 

G-protein coupled receptor, GPCR - 2pts

 

7-TMS protein, 7 trans-membranal alpha helical protein - 2pts

 

Hormone binds with receptor - 1 pt

 

G protein complex of alpha, beta, gamma subunits - 1 pt

 

G protein alphaGDP subunit catalyzed by GPCR and GTP to alphaGTP and GDP    - 2pts

 

AlphaGTP subunit released, binds to amplifier molecule - 2pts

 

Amplifier molecule = Adenylyl cyclase = 2pts

 

AlphaGTP/Adenylyl cyclase complex cleaves ATP ® cAMP -2pts

 

Performs ATP®cAMP cleavage multiple times - 1 pt

 

No diagram - minus 4

 

No words - minus 4

 

 

2.       ATP synthase machine

 

Diagram necessary - none, minus 4

 

Disk on top, three doubled globes below; shaft connecting two - 3 pts by itself IF text not supportive.

Disk made of c subunits (actually ab2c9-12) - 1 pt

Globes made of alpha, beta subunits (actually includes delta unit as well) - 1 pt

Shaft connecting consists of gamma subunit - 1 pt

Disk embedded in cristae membrane - 1 pt

Alpha/beta globes project into inner matrix - 1 pt

Beta subunit contains ADP binding site - 1 pt

H+ protons spin F0 disk of c subunits - 2 pts

F0 disk spins gamma shaft - 1 pt

Gamma shaft is asymmetrical - 1 pt

Gamma shaft "bumps" two alpha/beta F1 complexes for each H+ - 2 pts

Conformational change from gamma bumps causes ADP + Pi® ATP - 2 pts

Driven by H+ chemi-osmotic  gradient - 1 pt