1. Ch. 8: Harvesting Energy - Glycolysis & Cellular Respiration
- CR Intro
Case Study Athletes Boost Counts.pdf

2. 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

3. energy from sunlight photosynthesis C6H12O6 6 CO2 6 H2O 6 O2 cellular
Figure 8-1 Photosynthesis provides the energy released during glycolysis and cellular respiration
energy from sunlight
photosynthesis
C6H12O6 6
CO2 6
H2O 6 O2
cellular
respiration
glycolysis
ATP 3

4. 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

5. 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

6. Glycolysis
– Glycolysis video
– CR Rap

7. 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 –
Mitochondria structure
3 stages of cellular respiration
Pyruvate prep-step & Krebs cycle
2. ETC
3. Chemiosmosis

8. Formation of acetyl CoA (2C acetyl + coenzyme A):
1a- Pyruvate Prep Step
pyruvate (synthesized in cytosol during glycolysis) is actively transported into matrix
Formation of acetyl CoA (2C acetyl + coenzyme 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

9. 1b – Krebs Cycle or Citric Acid Cycle
a. Acetyl CoA + 4C molecule  6C citrate (citric acid) molecule
Acetyl CoA
released and recycled
c. Enzymes break down
acetyl group 
CO2 + 4C molecule
d. chemical energy
captured in NADH,
FADH2, ATP
CO2 becomes a
waste product
2 pyruvate generates (mitochondrial matrix reactions) 
2 ATP, 8 NADH, 2 FADH2 & 6 CO2
Formation of
acetyl CoA
NADH
NAD
FAD
FADH2
CO2
coenzyme A
coenzyme A
Krebs
cycle
acetyl CoA
NAD
NADH
ADP
ATP

10. Krebs Cycle or Citric Acid Cycle
- Krebs Song

11. 2 - ETC
series of electron transporting molecules embedded in inner mitochondrial membrane
(matrix)
1 H2O per 2 e-
ADP
ATP
– ETC Video
Donate e- & H+  P
- ETC Song
NADH
FADH2
NAD
FAD
ATP
synthase
(inner
membrane)
ETC
Energy either
1-lost as heat
2-pumps in H+
(intermembrane space) 11

12. 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 .
- Tyler Hamilton (Armstrong teammate)

13. https://www.youtube.com/watch?v=3y1dO4nNaKY ATP synthase
3 - Chemiosmosis
Chemiosmosis: process by which energy is used to generate a concentration of H+ to generate ATP
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

14. 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

15. STEPS
INPUT
OUTPUT
NET GAIN
Glycolysis
1 glucose
2 ATP
2 NAD
2 pyruvate
4 ATP
2 NADH
Pyruvate
Prep Step
2 NAD+
2 acetyl
groups
2 CO2
Krebs Cycle
2 acetyl 2CoA
6 NAD+
2 FAD
2 CoA
6 NADH
2 FADH2
4CO2
4 CO2
ETC
8-10 NADH
(1/2 O2)
8-10 NAD+
6H2O
32 ATP
TOTALS
Glucose
(+ O2)
6 CO2
36 ATP
- CR Review
– Crash Course in ATP and Respiration

16. 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
– Why Can You Get Fat by Eating Sugar?

17. 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

18. 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,
sour cream, cheese
– Fermentation Video

19. Figure 8-8 Glycolysis followed by lactic acid fermentation2
NAD 2
NADH 2
NADH 2
NAD
(glycolysis)
(fermentation)
1 glucose
2 pyruvate
2 lactate 2
ADP 2
ATP 19

20. 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 acid fermentation
in their leg muscle cells for their final burst of speed.
– Lactic Acid and Fatigue

21. Alcoholic Fermentation?
many microorganisms like yeast engage in alcoholic fermentation under anaerobic conditions
generates alcohol and CO2 from pyruvate
like in lactic
acid fermentation,
NAD+ must be
regenerated to
allow glycolysis
to continue
Making ginerale 2
NAD 2
NADH 2
NADH 2
NAD
(glycolysis)
(fermentation)
1 glucose
2 pyruvate
2 ethanol
2 CO2 2
ADP 2
ATP

22. 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.

23. 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.