BY 123 SI Session #5 Answer Key
Chapter 9: Cellular Respiration and Fermentation
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#1) Write the equation for cellular respiration.
C6H12O6 + 6O2  6CO2 + 6H2O + ENERGY
#2) In the conversion of glucose and O2 to CO2 and H2O, which molecule becomes reduced? Oxidized?
Which the oxidizing agent? Reducing Agent?
O2 has been reduced and is the oxidizing agent, Glucose has been oxidized and is the reducing agent.
#3) NAD+ is called an electron carrier . It’s reduced form is NADH.
It is a coenzyme that works with dehydrogenases.
#4) Order the steps of Glycolysis:
___4__ Fructose 1,6-bisphosphate is cleaved into two different three Carbon sugars
__9___ 2 H2O molecules are extracted, yielding PEP
___7__ 2 ADP are phosphorylated, producing 2 ATP. This leaves a three Carbon sugar with one
phosphate.
__1___ Phosphate group from ATP is transferred to Glucose.
__5___Isomerase enzyme catalyzes the conversion between two isomers, and Glyceraldehyde 3phosphate is used as a substract in the next step of the process.
__8___ Magic Chemistry happens and the phosphate group is relocated on the three Carbon sugar
__6___ Dehydrogenase enzyme catalyzes the oxidation of Glyceraldehyde 3-phospate by transferring
electrons from NAD+ forming NADH. The energy used from this transfer attaches a phosphate group to
the sugar.
__10___ Phosphate group transferred from PEP to ADP, forming ATP and Pyruvate
__2___ Glucose 6-phophate is converted into its isomer, Fructose 6-Phosphate
__3___ Phophofructokinase transfers a phosphate group to Fructose 6-phosphate (ATP used), forming a
sugar molecule with 2 phosphates.
#5) Recall how many kcal a Glucose molecule produced per mole. If a Glucose molecule releases this
much energy and one mole of ATP stores 7.3 kcal/mole, what percent of potential chemical energy in
Glucose has been transferred to ATP if one monosaccharide is available for cellular respiration.
A Glucose molecule has 686 kcal per mole of energy. Each ATP molecule has 7.3 kcal.mole of
energy. During the process of Cellular Respiration, 32 ATP are produced. Multiply 7.3 times 32 to get
233.6. Divide 233.6 by 686 kcal/mol to get 0.34. So, 34% of the potential chemical energy in Glucose is
transferred to ATP.
#4) A disaccharide is used for cellular respiration. What would the output of CO2, NADH’s, FADH’s, and
ATP’s be after the entire molecule made it through the Citric acid Cycle?
a.
b.
c.
d.
e.
2 CO2, 4 NADH, 1 FADH, and 1 ATP
4 CO2, 6 NADH, 2 FADH, and 2 ATP
8 CO2, 12 NADH, 4 FADH, and 4 ATP
4 CO2, 3 NADH, 1 FADH, and 2 ATP
4 CO2, 6 NADH, 4 FADH, and 2 ATP
#5) Which of the following reactions is incorrectly paired with its location?
a.
b.
c.
d.
e.
ATP synthesis – inner membrane of the mitochondria, mitochondrial matrix, and cytosol
Fermentation—cell cytosol
Glycolysis—cell cytosol
Substrate-level phosphorylation—cytosol and mitochondrial matrix
Citric acid cycle—cristae of mitochondria
#6) Glucose made from six radioactively labeled carbon atoms is fed to yeast cells in the absence of
oxygen. How many molecules of radioactive alcohol (C2H5OH) are formed from each molecule of
glucose?
a.
b.
c.
d.
e.
0
1
2
3
6
Process
Main Function
Inputs
Outputs
Glycolysis
Oxidation of glucose to
2 pyruvate, 2 ATP net
Glucose, 2 ATP, 2 NAD+,
4 ADP
2 Pyruvate, 4 ATP, 2
NADH + 2 H+ , 2 H2O
Pyruvate to Acetyl CoA
Oxidation of pyruvate
to acetyl CoA, which
then enters citric acid
cycle
2 Pyruvate, 2 CoA, 2
NAD+
2 acetyl CoA, 2 CO2, 2
NADH + 2 H+
Citric acid cycle
Acetyl CoA is combined
with oxaloacetate to
produce citrate, which
is cycled back to
oxaloacetate as redox
reactions produce
NADH and FADH2; ATP
is formed by substrate
level phosphorylation,
and CO2 is released
NADH and FADH2
transfer electrons to
electron transport
chain. In a series of
redox reactions, H+ is
pumped into
intermembrane space,
and electrons are
delivered to ½ O2.
Proton-motive force
drives H+ through ATP
synthase to make ATP
2 Acetyl CoA, 2 ADP, 6
NAD+, 2 FAD
4 CO2, 2 ATP, 6 NADH +
6 H+, 2 FADH2
10 NADH + 10 H+, 2
FADH2, H+ + O2, 28 ADP
10 NAD+, 2 FAD, H2O, 28
ATP (max)
Oxidative
phosphorylation
Fermentation
Anaerobic catabolism:
glycolysis followed by
oxidation of NADH to
NAD+ so glycolysis can
continue. Pyruvate is
either reduced to
alcohol and CO2 or to
lactate.
Same as Glycolysis, and
2 Pyruvate, 2 NADH
2 ATP, 2 NAD+, 2
ethanol, 2CO2 or 2
lactate.