1. Feel the Burn
Do you like to run, bike, or swim? These all are good ways to exercise. When you exercise, your body uses oxygen to get energy from glucose, a six-carbon sugar.
1. How does your body feel at the start of exercise, such as a long, slow run? How do you feel 1 minute into the run; 10 minutes into the run?
2. What do you think is happening in your cells to cause the changes in how you feel?
3. Think about running as fast as you can for 100 meters. Could you keep up this pace for a much longer distance? Explain your answer.

2. Chapter 9-1
Chemical Pathways

3. Chemical Energy & Food Food – source of:
 Raw materials
calorie  amount of energy needed to raise 1g of water by 1C
“Calorie” 1 kcal, or 1000 calories
Cells breakdown food slowly & gradually
Cells can’t use food energy directly  convert to ATP
If all at once, too explosive and most energy lost as heat
Slowly releases energy of food to make ATP

4. Cellular Respiration
The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen
6O2 + C6H12O6  6CO2 + 6H2O + Energy
Three main steps:
Glycolysis, Krebs cycle, Electron Transport Chain
oxygen
glucose
carbon dioxide
water

5. Electron Transport Chain
Section 9-2
Flowchart
Cellular Respiration
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain
Carbon
Dioxide
(CO2) +
Water
(H2O)

6. Fermentation (without oxygen)
Chemical Pathways
Section 9-1
Glucose
Krebs cycle
Electron transport
Glycolysis
Alcohol or lactic acid
Fermentation (without oxygen)

7. Electron Transport Chain
Cellular Respiration: 3 Stages Glycolysis ( in cytoplasm)
2. Krebs Cycle ( in mitochondria)
3. Electron Transport Chain ( in mitochondria)
Glucose
Glycolysis
Cytoplasm
Pyruvic acid
Electrons carried in NADH
Krebs Cycle
Electrons carried in NADH and FADH2
Electron Transport Chain
Mitochondrion

8. Net vs. Gross Gross  amount of product made
Ex: Made $20.00 babysitting
Net  amount of product made minus amount of product used
Ex: Made $15.00 babysitting
$5.00 for gas to get to babysitting job
$20.00 babysitting made
$ $5.00 = $15.00 net

9. Glycolysis
Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound.
6 carbon molecule (glucose) to two 3-carbon molecules (pyruvic acid)
Takes place in the cytoplasm
Does not require oxygen

10. Glycolysis 2 ATP molecules must be added to get the reaction started
Can be considered activation energy
4 ATP molecules are produced (4 – 2 = net gain of 2 ATP)
2 NADH molecules are also created
NADH
Electron carrier =  NAD+ (nicotinamide adenine dinucleotide)
NAD+ + H+ + 2 high energy electrons  NADH
Takes electrons to other parts of respiration
Glycolysis nets  2 ATP, 2 NADH, and 2 pyruvic acids

11. To the electron transport chain
Glycolysis
Glucose
2 Pyruvic acid
To the electron transport chain

12. Glycolysis: Advantages vs. Disadvantages
 Occurs quickly
Can produce 1000s of ATP in a few milliseconds
 Does not require oxygen
Can occur w/o oxygen
Disadvantages
 Net gain of only 2 ATP
 NAD+ become filled with electrons quickly
Can’t make more ATP

13. Anaerobic Respiration = Fermentation
an = “without” aerobic = “air”
 Occurs after glycolysis only if no oxygen is available
NADH from glycolysis used, turned back into NAD+
Goes back to glycolysis
Keeps glycolysis going
Generate as many ATP as possible
Important because it recycles the NAD+ molecules so that the cell can continue to make energy

14. Alcoholic Fermentation
 In the absence of oxygen, pyruvic acid is broken down to produce alcohol and carbon dioxide
Carried out by yeasts and a few other microorganisms
pyruvic acid + NADH → alcohol + CO2 + NAD+
 Used to make alcoholic beverages and to cause bread dough to rise

15. Lactic Acid Fermentation
 In many cells, the pyruvic acid that accumulates due to glycolysis is converted to lactic acid.
pyruvic acid + NADH → lactic acid + NAD+
 Occurs in muscles during heavy exercise
Lactic acid buildup in muscles causes painful, burning sensation = why muscles feel sore
 Prokaryotes also produce lactic acid
Used to make cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut, and kimchi.

16. Lactic Acid Fermentation
Glucose
Pyruvic acid

17. Respiration Videos
Aerobic Respiration
Glycolysis

18. Review Questions
1. What is cellular respiration? What is the equation for it?
2. What are the 3 stages of cellular respiration in order?
3. What is glycolysis and where does it take place in a cell? What are the products of glycolysis?
4. What are the advantages and disadvantages of glycolysis?
5. What is anaerobic respiration and what is its purpose?
6. Compare and contrast alcoholic fermentation with lactic acid fermentation.