1. Cellular Respiration
Chapter 8.3

2. Introduction
Respiration is a process in which living cells break down glucose and release its stored energy in the form of ATP
Respiration is necessary for life.
Organisms obtain energy in a process called cellular respiration.
The equation for cellular respiration is the opposite of the equation for photosynthesis.

3. Introduction 6. Cell respiration occurs in ALL cells.
7. It begins with glycolysis, and continues with either anaerobic respiration (AKA fermentation) if oxygen is absent or aerobic respiration if oxygen is present.

4. Organic Compounds C6H12O6 ATP Glycolysis ATP Oxygen Absent
First Stages of Cellular Respiration
Organic Compounds C6H12O6
ATP
Glycolysis
ATP
Oxygen Absent
Oxygen Present
Fermentation
Aerobic Respiration

5. Glycolysis
Occurs in the cytoplasm
Can occur with or without oxygen
Glucose is split into 2 molecules of pyruvic acid (which is a 3 carbon compound)
In addition to pyruvic acid, 2 molecules of ATP and 2 molecules of NADH are formed for each molecule of glucose that is broken down.

6. Glycolysis
5. End products of glycolysis a. 2 ATP (makes 4 but uses 2 ATP) b. 2 molecules of pyruvic acid c. 2 NADH d. 2 H2O 6. What happens to the pyruvic acid depends on: a. The organism involved b. presence or absence of oxygen

7. Overview of Glycolysis

8. Fermentation
Defined as the process of breaking down pyruvic acid without the use of oxygen
Also called anaerobic respiration
Does not produce ATP
Does produce NAD+ which is reused during glycolysis
2 forms of fermentation:
a. Lactic acid fermentation
b. alcoholic fermentation

9. Lactic Acid Fermentation
1. Pyruvic acid from glycolysis is converted into a molecule called lactic acid.
2. Heavy exercise is often the reason for the lack of oxygen that prevents pyruvic acid from continuing on to aerobic respiration. This can cause a build up of lactic acid that results in cramping and muscle soreness.
3. End products of lactic acid fermentation:
a. Lactic acid
b. NAD+ (used in glycolysis)
c. 2 ATP (actually made during glycoysis)

10. Overview of Lactic Acid Ferm.

11. Alcoholic Fermentation
Occurs in the cytoplasm of some plant cells and some unicellular organisms such as yeast under anaerobic conditions
Pyruvic acid from glycolysis is converted to ethyl alcohol
End products:
a. Ethyl alcohol
b. Carbon dioxide
c. NAD+ (used in glycolysis)
d. 2 ATP (actually made during glycolysis)

12. Overview of Alcoholic Ferm.

13. Aerobic Respiration Occurs after glycolysis Occurs in the mitochondria
Requires the presence of oxygen (aerobic)
3 steps to aerobic respiration
a. Formation of acetyl CoA
b. Krebs cycle
c. Electron Transport Chain

14. Aerobic Respiration

15. Formation of Acetyl CoA
Pyruvic acid (from glycolysis) enters the mitochondria through a transport protein
It joins with coenzyme A (CoA) to produce Acetyl CoA
In the process, NADH is produced
Acetyl CoA can then enter the Krebs cycle

16. Formation of Acetyl CoA

17. Krebs cycle AKA citric acid cycle Occurs in the matrix of mitochondria
Discovered by Sir Hans Krebs in 1937
Steps:
a. acetyl enters the cycle to combine with oxaloacetic acid  citric acid
b. coenzyme A is released to be used again
c. citric acid – carbon dioxide  oxaloacetic acid (used again)

18. Krebs cycle
5. During the cycle, carbon dioxide is released, NADH and FADH2 are formed, and ATP is produced 6. End results a. 6 NADH b. 4 CO2 c. 2 ATP d. 2 FADH2

19. Citric Acid Cycle

20. Krebs cycle
7. The carrier molecules (NADH and FADH2) transport electrons from the Krebs cycle to the ETC where water and more ATP are formed

21. ETC Occurs in the inner membrane of mitochondria
Electrons are donated to the ETC by NADH and FADH2
ATP is generated by chemiosmosis
The function of oxygen is to act as the final hydrogen acceptor to produce water
Each NADH produces 3 ATP
Each FADH2 produces 2 ATP

23. ETC
6. The ETC produces 10 NADH  30 ATP 2 FADH2  4 ATP 34 ATP

24. Total ATP produced
Glycolysis  2 ATP Krebs cycle  2 ATP ETC  34 ATP *38 ATP from 1 molecule of glucose

25. Review of Aerobic Respiration

26. Respiration
-Aerobic respiration is important because it produces way more ATP than anaerobic respiration (38 ATP to 2 ATP)

27. Review of Respiration