Ch. 8: Harvesting Energy Glycolysis & Cellular Respiration
Case Study Athletes Boost Counts.pdf
http://www.sumanasinc.com/webcontent/animations/content
/cellularrespiration.html - CR Intro
8.1: How Do Cells Obtain Energy?
 photosynthesis  ultimate source of energy.
 photosynthetic organisms capture sun’s energy and store it in form of
glucose
 6 CO2  6 H2O  light energy  C6H12O6  6 O2
 nearly ALL organisms use glycolysis & cellular respiration to break
down sugar and capture the released energy as ATP
 C6H12O6  6 O2  6 CO2  6 H2O  ATP energy  heat energy
 cells break down glucose in 2 stages
 glycolysis liberates a small quantity of ATP
 cellular respiration produces a lot of ATP
Figure 8-1 Photosynthesis provides the energy released during glycolysis and cellular respiration
energy from sunlight
photosynthesis
6 CO2
6 H2O
6 O2
cellular
respiration
C6H12O6
glycolysis
ATP
8.1: How Do Cells Obtain Energy?
Glucose is a key energy-storage
molecule
 all cells metabolize glucose
 plants covert glucose  sucrose or starch
 humans & many other animals store energy in glycogen & fat
glycogen
starch
8.2: What Happens During Glycolysis
Glycolysis (“sweet”, “split apart”): series of enzyme catalyzed reactions that
splits 6-C glucose into 2 molecules of pyruvate
 Energy investment stage:
 1 glucose + 2 ATP  1 fructose bisphosphate
 Energy harvesting stage:
 fructose bisphosphate  2 G3P  pyruvate
 2 ATP generated from each G3P but 2 were used to form fructose
bisphosphate (net gain ATP = 2/glucose)
 2 G3P donates 2 e- & a H+ ion to NAD+  NADH
Glycolysis
https://www.youtube.com/watch?v=hDq1rhUkV-g – Glycolysis video
https://www.youtube.com/watch?v=EfGlznwfu9U – CR Rap
Ch. 8.3: What Happens During Cellular Respiration
 Cellular respiration: breaks down 2 pyruvate molecules into
6CO2 & 6 H2O and produces 32 ATP in the mitochondria
https://www.youtube.com/watch?v=pOfyuoa0Ywc –
Mitochondria structure
 3 stages of cellular respiration
1. Pyruvate prep-step & Krebs cycle
2. ETC
3. Chemiosmosis
1a- Pyruvate Prep Step
 pyruvate (synthesized in cytosol during glycolysis) is actively
transported into matrix
 Formation of acetyl CoA (2C acetyl + coenzyme A):
a. pyruvate splits releasing CO2
and leaves behind an acetyl group
b. acetyl group reacts with CoA 
acetyl CoA
c. transfers liberated energy to
NAD+  NADH
1b – Krebs Cycle or Citric Acid Cycle
a. Acetyl CoA + 4C molecule  6C citrate (citric acid) molecule
b. Acetyl CoA
released and recycled
2 pyruvate generates (mitochondrial matrix reactions) 
c. Enzymes break down
acetyl group 
CO2 + 4C molecule
d. chemical energy
captured in NADH,
FADH2, ATP
2 ATP, 8 NADH, 2 FADH2 & 6 CO2
Formation of
acetyl CoA
coenzyme A
NADH
NAD
CO2
e. CO2 becomes a
waste product
FADH2
coenzyme A
acetyl CoA
NAD
FAD
Krebs
cycle
NADH
ADP
ATP
Krebs Cycle or
Citric Acid Cycle
https://www.youtube.com/watch?v=
JPCs5pn7UNI - Krebs Song
2 - ETC
series of electron transporting molecules
embedded in inner mitochondrial
membrane
(matrix)
Donate
e-
&
ADP

P
1 H2O per 2 e-
H+
FADH2
NADH
NAD
ETC
Energy either
1-lost as heat
2-pumps in H+
ATP
synthase
FAD
(inner
membrane)
(intermembrane space)
ATP
https://www.youtube.com/watch?v=
xbJ0nbzt5Kw – ETC Video
http://www.nclark.net/ElectronTrans
portChain.mp3 - ETC Song
Boosting Blood Counts: Do Cheaters Prosper?
When people and other animals exercise vigorously, they are
unable to get enough air into their lungs, enough oxygen into their
blood, and enough blood circulating to their muscles to allow
cellular respiration to meet all their energy needs. As oxygen
demand exceeds oxygen supply, muscles must rely on glycolysis
(which yields far less ATP than does cellular respiration) for
periods of intense exercise. This explains why some athletes,
desperate for a competitive edge, may turn to illegal blood doping to increase
the ability of their blood to carry oxygen .
https://screen.yahoo.com/tyler-hamilton-blood-doped-162214802.ht - Tyler Hamilton (Armstrong teammate)
3 - Chemiosmosis
Chemiosmosis: process by which energy is used to generate a concentration of H+ to
generate ATP
https://www.youtube.com/watch?v=3y1dO4nNaKY ATP synthase
 carrier proteins transport
1. ATP : matrix  intermembrane space
2. ADP : intermembrane space  matrix
 ATP molecules diffuse through large pores in
outer mitochondrial membrane and into cytosol
 a person produces, uses, and then regenerates
the equivalent of roughly his or her body weight of
ATP daily
 Chemiosmosis yields 32 ATP
Why is Cyanide So Deadly?
 common murder weapon where victims of the poison die almost instantly
 blocks the last protein in the ETC which is an enzyme that combines
electrons with oxygen
 if energy-depleted electrons are not carried away by oxygen, they act like a
plug preventing high energy electrons from traveling the ETC
 no more H+ can be pumped across
membrane and therefore, no chemiosmosis
 can kill within a few minutes
STEPS
INPUT
OUTPUT
Glycolysis
1 glucose
2 ATP
2 NAD
2 pyruvate
4 ATP
2 NADH
2 pyruvate
2 NAD+
2 acetyl
groups
2 NADH
2 CO2
Pyruvate
Prep Step
Krebs
Cycle
ETC
TOTALS
2 acetyl
2CoA
6 NAD+
2 FAD
2 CoA
6 NADH
2 FADH2
4CO2
2 ATP
8-10 NADH
2 FADH2
(1/2 O2)
8-10 NAD+
2 FAD
6H2O
32 ATP
Glucose
(+ O2)
6 CO2
6H2O
http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html - CR Review
https://www.youtube.com/watch?v=00jbG_cfGuQ – Crash Course in ATP and Respiration
NET
GAIN
2 ATP
2 CO2
4 CO2
2 ATP
32 ATP
36 ATP
Cellular Respiration Can Extract Energy from a Variety of Molecules
Glucose  sucrose, starch, protein & fat can enter CR stages and be broken
down to produce ATP
ATP  not used for long term storage b/c it becomes unstable
Fats  stable and store 2X as much energy for their weight as carbs
Candy bar (sucrose) glucose + fructose (metabolized in liver)  G3P
 If cells have plenty of ATP some G3P diverted from CR to make glycerol.
 Excess acetyl CoA used to make fatty acids
https://www.youtube.com/watch?v=EwqNp9cO_-4 – Why Can You Get Fat by Eating Sugar?
8.4 What Happens During Fermentation?
 glycolysis – used by virtually all organisms
 earlier life forms appeared under anaerobic conditions (no O2) existing
before photosynthesis
 some organisms lack enzyme for cellular respiration and rely solely on
fermentation while others live in places with little to no O2
- stomachs and intestines of animals
- deep in soil, bogs, etc
 2 types of fermentation
a. lactic acid fermentation: pyruvate  lactic acid
b. alcoholic fermentation: pyruvate  ethanol & CO2
 fermentation allows NAD+ to be recycled when O2 is absent
 production of NAD+ is necessary for glycolysis to continue
 does not produce an ATP
Lactic Acid Fermentation
 NO O2 = muscles stop
 muscles rely on glycolysis for
2 ATP/glucose molecule
 muscle cells ferment resulting
pyruvate to lactate using e- & H+
from NADH
 microorganisms  milk to yogurt,
https://www.youtube.com/watch?v=LDh1O4Zk7Xc – Fermentation Video
sour cream, cheese
Figure 8-8 Glycolysis followed by lactic acid fermentation
2
NAD
2 NADH
2
NADH
(glycolysis)
2
ADP
2
NAD
(fermentation)
2 pyruvate
1 glucose
2
ATP
2 lactate
Blood Doping: Do Cheaters Prosper?
Why is the average speed of the 5,000-meter run in the Olympics slower
than that of the 100-meter dash? During the dash, runner’s leg muscles use
more ATP than cellular respiration can supply. But anaerobic fermentation
can only provide ATP for a short dash. Longer runs must be aerobic, and
thus slower, to prevent lactic acid buildup from causing extreme fatigue,
muscle plain, and cramps.
 Sprinters rely on lactic
in their leg muscle cells for
speed.
acid fermentation
their final burst of
https://www.youtube.com/watch?v=DGq94gpKEbg – Lactic Acid and Fatigue
Alcoholic Fermentation?
 many microorganisms like yeast engage in alcoholic fermentation under
anaerobic conditions
https://www.youtube.com/watch?v=4SosPuWAg7g
Making ginerale
 generates alcohol and CO2 from pyruvate
 like in lactic
acid fermentation,
NAD+ must be
regenerated to
allow glycolysis
to continue
2 NAD
2 NADH
2 NADH
(glycolysis)
2 pyruvate
ADP
NAD
(fermentation)
1 glucose
2
2
2
ATP
2 ethanol
2 CO2
Blood Doping: Do Cheaters Prosper?
Although runners who do the 100-meter dash rely heavily on lactic acid
fermentation to supply ATP, long distance athletes including cyclists, marathon
runners, and cross-country skiers must pace themselves. They must rely on aerobic
cellular respiration for most of the race, saving the anaerobic spring for the finish.
Training for distance events focuses on increasing the capacity of the athletes’
respiratory and circulatory systems to deliver enough oxygen to their muscles. Blood
doping most often occurs among distance athletes seeking to increase the oxygen
carrying capacity of their blood so that cellular respiration can generate the maximum
amount of ATP from glucose.
The EPO-mimicking drug CERA – that the disgraced cyclist Ricco now admits
having taken –helped keep his muscles supplied with ATP by stimulating
overproduction of oxygen-carrying red blood cells. In the particularly demanding
mountain stages of the Tour de France, which Ricco won, his clean competitors were
at a disadvantage because their leg muscles became painfully laden with lactate from
fermentation sooner than Ricco’s did.
Blood Doping: Do Cheaters Prosper?
Because EPO is produced naturally in the human body, its abuse is hard to detect.
CERA, developed for use by people with anemia (who have too few red blood cells),
was new on the market at the time of the 2008 Tour de France, and Ricco may have
assumed it would be undetectable. But CERA’s manufacturer, the pharmaceutical firm
Hoffman-La Roche, had provided samples of the drug to the World Anti-Doping
Agency before it was marketed, allowing researchers to develop urine tests to identify
users. This led to Ricco’s exposure and disgrace, and his team’s devastating
disappointment.
1. Some athletes move to high-altitude locations to train for races run at lower
altitudes because the low oxygen levels at high altitudes stimulate increased
production of red blood cells.
 Is this cheating? Explain your reasoning.
2. Advances in gene therapy may one day make it possible to modify athletes’ cells so
that they have extra copies of the gene that produces EPO.
 Is this cheating? Explain your reasoning.