Download Study guide for Midterm 3.

Study guide for Midterm 3.
1. Isolated mitochondria are suspended in a buffer containing ADP, Pi, and an
oxidizable substrate such as succinate. According to the graph below, the
lower (red) line indicates the ATP production and the above (black) line the
consumption of oxygen.
a. Why there is neither O2 consumed nor ATP synthesized until ADP and
Pi are added to the succinate solution?
b. Explain the effect of Venturicidin or oligomycin to the respiratory
chain. If they block the respiratory chain, why there is no ATP
synthesized?
c. DNP is a hydrophobic acid molecule. Explain its effect.
2. The acetyl group of acetyl-CoA, produced by the oxidative decarboxylation of
pyruvate in the mitochondrion, is transferred to the cytosol by the acetyl
group shuttle outlined in Figure 21-10.
a. Write the overall equation for the transfer of one acetyl group from
the mitochondrion to the cytosol.
b. What is the cost of this process in ATPs per acetyl group?
c. In Chapter 17 we encountered an acyl group shuttle in the transfer of
fatty acyl–CoA from the cytosol to the mitochondrion in preparation
for β oxidation (see Fig. 17-6). One result of that shuttle was
separation of the mitochondrial and cytosolic pools of CoA. Does the
acetyl group shuttle also accomplish this? Explain.
3. Consider a preparation that contains all the enzymes and cofactors necessary
for fatty acid biosynthesis from added acetyl-CoA and malonyl-CoA.
a. If [2-2H]acetyl-CoA (labeled with deuterium, the heavy isotope of
hydrogen) and an excess of unlabeled malonyl-CoA are added as
substrates, how many deuterium atoms are incorporated into every
molecule of palmitate? What are their locations? Explain.
b. If unlabeled acetyl-CoA and [2-2H]malonyl-CoA are added as
substrates, how many deuterium atoms are incorporated into every
molecule of palmitate? What are their locations? Explain
4. When an animal confronts a “fight-or-flight” situation, the release of
epinephrine promotes glycogen breakdown in the liver, heart, and skeletal
muscle. The end product of glycogen breakdown in the liver is glucose; the
end product in skeletal muscle is pyruvate.
What is the reason for the different products of glycogen breakdown in the
two tissues?
5. Why does citrate inhibit phosphofructokinase-1 (PFK-1)?
6. After few days of starvation the concentration of glucose in blood decreases
and the concentration of ketone bodies increase. Are these two phenomena
connected? Why?
7. Associate all the conditions that apply for each pathway:
Conditions
a. Happens in the cytosol
b. Happens in mitochondria
c. Happens in mitochondrial inner membrane
d. Uses NADPH as reactant
e. Uses FADH2 as reactant
f. Uses NAD+ as reactant
g. Uses NADP+ as reactant
h. Uses FAD as reactant
i.
j.
k.
l.
Takes place in the liver between meals and during fasting
Takes place in the liver right after a meal
The pathway uses CO2 to activate a molecule
It requires a shuttle to transport an electron carrier across the
mitochondrial membrane.
m. It requires a shuttle to transport some of the necessary metabolites
across the mitochondrial membrane.
n. It’s a cycle that takes place between different organs.
Pathways
I.
Glycolysis: From glucose to pyruvate.
II.
Gluconeogenesis. From pyruvate to glucose.
III.
Fatty acid biosynthesis
IV.
Cori Cycle
V.
Oxidative phosphorylation
VI.
Amino acid catabolism. From any amino acid to urea.
VII.
Alanine-glucose cycle
VIII.
Fatty acid beta-oxidation
IX.
Pentose phosphate pathway
X.
Fermentation. From pyruvate to lactate.
XI.
Formation of ketone bodies.