1. Cellular Respiration Overview
AP BIO

2. Cellular Respiration Organic Compounds Oxygen Water Energy + CO2 + +
Aerobic Cellular Respiration occurs in the presence of oxygen in the cytosol and the mitochondria
The process can be summarized as:
C6H12O6 + 6O2  6CO2 + 6H2O + Energy (ATP and Heat)
Organic
Compounds
Oxygen
Water
Energy +
CO2 + +

3. Redox Reaction
Redox Reactions – Reactions involving the transfer of electrons
Oxidation – When a substance loses electrons in a redox reaction
The substance accepting the electron is known as the oxidizing agent
Reduction – When a substance gains electrons in a redox reaction
The substance donating the electron is known as the reducing agent

4. Example: Sodium Chloride
Becomes Oxidized (loses electron)
Oxidizing
Agent + Na Cl - Na Cl + +
Reducing
Agent
Becomes Reduced (gains electron)

5. Production of ATP C6H12O6 6O2 6CO2 6H2O + + + Energy Becomes Oxidized
Oxidizing
Agent
C6H12O6
6O2
6CO2
6H2O + + +
Energy
Reducing
Agent
Becomes Reduced

6. Overview of the Process
With oxygen present, there are 3 main steps in cellular respiration:
Glycolysis
The Citric Acid Cycle (Krebs Cycle)
Oxidative Phosphorylation: ETC and chemiosmosis

7. Citric Acid Cycle ATP ATP ATP Glycolysis Oxidative Phosphorylation:
NADH
NADH and FADH2
Oxidative
Phosphorylation:
ETC
And
Chemiosmosis
Citric
Acid
Cycle
Glycolysis
Glucose
Pyruvate
ATP
ATP
ATP

8. Types of Phosphorylation
Phosphorylation is how ATPs are formed
Oxidative Phosphorylation – Phosphates added to ADP via the redox reactions in the ETC
Substrate Level Phosphorylation – An enzyme transfers a phosphate from a substrate, to ADP (glycolysis and citric acid cycle)

9. Glycolysis Glyco=Sugar; Lysis= Split
In Gylcolysis, Glucose is split into two 3-carbon pyruvate (pyruvic acid) molecules
In order to begin, glycolysis requires the input of energy (ATP)
Glycolysis occurs in the cytosol
Lets look at Glycolysis in a very simple form:

10. Glycolysis (Simplified)
2 ATP are added in the presences of glucose
2 NADH are produced
4 ATP are produced (Net gain of 2)
2 Pyruvate molecules are formed

11. 4 ADP 2 ADP 2ATP Glucose 4ATP 2 NADH Pyruvic Acid 2 NAD+ C C C C C C C

12. Citric Acid Cycle Also referred to as the Krebs Cycle
Takes place in the matrix
When oxygen is present, the Citric Acid Cycle follows Glycolysis
This cycle takes pyruvate from glycolysis to make ATP, NADH, and FADH2

13. Citric Acid Cycle Simplified
Pyruvate turns into acetyl CoA via coenzyme A (CoA) (this is the link between glycolysis and the Citric Acid Cycle)
Acetyl CoA enters the Citric Acid Cycle and is then transformed into citrate
There are 7 intermediate molecules, until Oxaloacetate is reformed to begin the cycle again

15. Citric Acid Cycle - Products
3 NADH, 1 FADH2, 1ATP, and CO2 are produced in the Citric Acid Cycle
Each NADH will generate about 3 ATP
FADH2 will generate about 2 ATP
The CO2 released from this cycle is the same CO2 that you exhale while breathing

16. Oxidative Phosphorylation
This is the process of extracting ATP form the energy in NADH and FADH2
Occurs in the cristae of the mitochondria
The electrons are passed through an ETC to release ATP
The final electron acceptor is oxygen
Oxygen bonds with 2 electrons (carried by Hydrogen) to produce water

17. e-
ADP
ATP
ADP
ATP
ADP
ATP
Energy Level
ADP
ATP H O

18. Totals
+2 ATP ATP ATP = 36 ATP
ETC
Glycolysis
Krebs
Cycle

19. Anaerobic Environments
When no oxygen is present, the cell will have to do one of two things:
Die due to the fact that there is no Oxygen to accept electrons at the end of oxidative, so no more NAD+ are made or
They can undergo Fermentation:
Lactic Acid
Alcoholic

20. Fermentation Takes place in the mitochondrial inner membrane
Does not require oxygen to occur
Does not directly produce ATP

21. Lactic Acid Fermentation
Pyruvate comes from glycolysis and is turned into lactate (lactic acid)
NADH gives an electron to become NAD+

22. Alcoholic Fermentation
Pyruvate comes from glycolysis, and is changed into acetaldehyde, and a CO2 is given off in the process
Acetaldehyde is turned into ethanol with the help of an electron from NADH
The products are CO2, Ethanol, and NAD+

23. Why fermentation? Why do cells switch to fermentation?
Why can’t cells use glycolysis and the Krebs cycle in an anaerobic environment?
Right now with your table compare and contrast aerobic and anaerobic respiration