1. The process of cellular respiration
Section 9.2

2. Glycolysis The first set of reactions Means – sugar breaking
Glucose is transformed through chemical steps
Pyruvic acid is generated (3 carbons)
As carbon bonds are broken energy is released

3. Overview of glycolysis
Energy is required to break glucose
Overall net energy gain in the reaction
NAD+ accepts high energy electrons
Process is very fast
Thousands of ATP molecules produced in milliseconds
Does not require oxygen

4. Krebs cycle
Pyruvic acid is broken down to carbon dioxide by a series of energy forming reactions
Also known as citric acid cycle
Pyruvic acid passes through mitochondrial membrane into matrix
1 carbon atom from pyruvic acid becomes part of CO2 molecule
Remaining carbon form acetic acid
In the Krebs cycle, the acetic acid (acetycl CoA) combines with a 4-carbon compound
Produces citric acid

5. Krebs cycle continued….
Citric acid is progressively broken down to a 4 carbon molecule again
Electrons are transported to NADH and FADH2
At 5 points around the cycle
Each cycle one molecule of ADP is converted to ATP
1 pyruvic acid = 1 ATP
Carbon dioxide is released
ATP can be used straight away
NADH and FADH2 feed the electron transport chain

6. Electron transport and ATP synthesis
NADH generated from glycolysis enters the mitochondria and joins electron carriers produced by Krebs cycle
These all feed into the electron transport chain
In Eukaryotes located in inner membrane of mitochondrion
In Prokaryotes located in cell membrane
At the end of the chain an enzyme combines electrons to form water
Oxygen is the final acceptor of electrons and removes waste H+ ions
Without oxygen the chain can’t function!

7. Electron transport and ATP synthesis cont…
The energy from the electrons is used to pump H+ ions across the membrane
H+ ions build up in intermembrane space
Becomes positively charged relative to the matrix
Matrix is negatively charged relative to membrane space
The potential energy from this charge difference to generate ATP via chemiosmosis
ATP generated from turbine like ATP synthase
One pair of high energy electrons can generate 3 ATP molecules

8. How much ATP does cellular respiration generate
Together glycolysis, the krebs cycle and electron transport chain generate 36 molecules of ATP per glucose molecule
Produces 18 times the amount possible by anaerobic respiration
36 ATP vs 2 ATP
We don’t just eat carbohydrates
Lipids and proteins enter the Krebs cycle or glycolysis at one of many places
Cells can generate ATP from many things
36 ATP is 36 % of total energy of glucose
Remaining 64 % released as heat
Explains why body temp is 37 C
Why you feel warm after exercise