Name: _________________________
Exam III
Total: 100 points
1.(14pts) On the back of this sheet, write out the pathway for glycolysis from glucose to pyruvate. Indicate the products of glycolysis and where they are formed. Label the steps catalyzed by regulatory enzymes and name those enzymes.
See
Fig. 16.2
2.(6pts) Name the following molecules.
|
|
A. |
B. |
|
molecule |
coenzyme
A |
chlorophyll |
3.(14pts) A. Write out the pathway for mitochondrial electron transport from succinate to O2. Write out the complete name of the complexes (not just the numbers). CIRCLE the integral membrane proteins that pump protons.
succinate--succinate dehydrogenase--coenzyme Q--cytochrome bc1 complex--cytochrome c--cytochrome oxidase--O2
B. Briefly
describe the mechanism of ATP synthesis by ATP synthase
in oxidative phosphorylation.
Protons flow through the Fo
channel (the a subunit half channel), protonating an aspartate on one
of the c subunits. This causes rotation
of the c subunits and flow of the proton through the other half channel of the a subunit. The
rotation results in rotation of the g subunit of F1. This produces a conformational change in the b subunits. The T
(tight) site becomes and O site and releases ATP, the L (loose) site becomes a
T site and forms a new ATP, and the O (open) site becomes an L site and binds
ADP and Pi
4.(10pts) A. Name the regulatory enzyme for the Calvin cycle.
Rubisco
B. Write out the carbon fixation reaction catalyzed by this
enzyme. Include all substrates and
products.
Ribulose 1,5-bisphosphate + CO2 = 2 3-phosphoglycerate
C. Briefly describe carbon fixation in a C4 plant.
CO2 is fixed to make a C4 intermediate (oxaloacetate) in the mesophyll
cells of the leaf. Oxaloacetate
is converted to malate,
which moves to the bundle sheath cells. Malate is converted to pyruvate and CO2 in the bundle sheath cells,
where the enzymes of the Calvin cycle are located. This results in higher concentrations of CO2
at the site of rubisco and minimizes the oxygenase activity of rubisco.
5.(3pts) What is the function of the nonoxidative branch of the pentose phosphate pathway?
It converts C5 intermediates from the oxidative branch to 2 C6 and C3 glycolytic intermediates and vice versa.
6.(12pts) Fill in the blanks.
A. Phosphorolysis of glycogen by glycogen phosphorylase produces
(product
of the reaction) glucose 1-phosphate
B. The form of muscle glycogen phosphorylase that is predominantly in the R state is
(give
the name) phosphorylase a
C. The protein that removes the a1-6 branches in glycogen is
debranching enzyme
D. The protein at the core of the glycogen particle is glycogenin.
E. In response to epinephrine, glycogen phosphorylase is phosphorylated and activated by the enzyme
phosphorylase kinase
F. Glycogen synthase is phosphorylated and inactivated by the enzyme
protein kinase A
7.(7pts) Draw or describe the cascade by which epinephrine binding to the b-adrenergic receptor causes mobilization of stored triacylglycerols.
Fig. 22.6 plus perilipin
8.(9pts) A. Fatty acids are transported into the mitochondria attached to
carnitine
B. Name the products of each round of b-oxidation of fatty acids.
|
acetyl CoA |
NADH |
FADH2 |
C. Name the
cofactor for acetyl CoA carboxylase
biotin
D. How many NADPH does fatty acid synthase require to make a C16 fatty acid?
14
9.(9pts) A. Write out the reaction for the pyruvate dehydrogenase complex.
pyruvate + CoASH + NAD+ = acetyl CoA + CO2 + NADH + H+
B. Name the three regulatory enzymes of the citric acid cycle.
citrate synthase, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase complex
10.(16pts) Define:
A. catabolism-breakdown of foodstuffs to make ATP
B. anaplerotic reaction (define and give one example)-reaction that replenishes citric acid cycle intermediates (pyruvate carboxylase)
C. gluconeogenesis-synthesis of glucose from non-carbohydrate precursors such as lactate, propionate, glycerol or amino acids
D. catalase-enzyme that converts
hydrogen peroxide to oxygen plus water