1. 3 parts of Respiration Glycolysis – may be anaerobic
TCA – Kreb’s Cycle
Electron Transport Chain
aerobic – require oxygen

2. Electron Transport Chain
a.k.a cytochrome chain
Main ATP producer!
Chemiosmotic theory explains how the cytochrome chain produces ATP
Step 1: creating a H+ concentration gradient
Step 2: using the gradient to make ATP

3. Creating a Potential
Carrier molecules (cytochromes) in the inner membrane transport H+ out; accumulates in the intermembrane space
Creates an electrochemical gradient!

4. Click here for ETC
Click here for ATP synthase close-up

5. Creating a Potential NADH and FADH2 bring H atoms to the chain.
e- are stripped off and passed down the chain of cytochromes
Oxygen becomes the final electron acceptor to form water.

6. Using the gradient to make ATP

7. Glycolysis Citric acid cycle
Electron shuttles
span membrane
CYTOSOL
MITOCHONDRION
2 NADH or
2 FADH2
2 NADH
2 NADH
6 NADH
2 FADH2
Glycolysis
Oxidative
phosphorylation:
electron transport
and
chemiosmosis 2
Acetyl
CoA
Citric
acid
cycle 2
Pyruvate
Glucose
+ 2 ATP
+ 2 ATP
+ about 32 or 34 ATP
Summary
Respiration starts with glycolysis. This occurs in the cytosol. One glucose molecule is split to produce 2 pyruvate molecules. In the process, 2 NADH and 2 ATP molecules are produced. NADH carries energy into the mitochondrion to fuel other steps.
Glycolysis enters the matrix of the mitochondrion. Prior to entering the Krebs Cycle, pyruvate must be converted into acetyl CoA (pronounced: acetyl coenzyme A). This is achieved by removing a CO2 molecule from pyruvate and then removing an electron to reduce an NAD+ into NADH. An enzyme called coenzyme A is combined with the remaining acetyl to make acetyl CoA which is then fed into the Krebs Cycle.
What happens to the NADH2+ and FADH2 produced during the Krebs cycle? The molecules have been reduced, receiving high energy electrons from the pyruvic acid molecules that were dismantled in the Krebs Cycle. Therefore, they represent energy available to do work. These carrier molecules transport the high energy electrons and their accompanying hydrogen protons from the Krebs Cycle to the electron transport chain in the inner mitochondrial membrane.
Once the electrons (originally from the Krebs Cycle) have yielded their energy, they combine with oxygen to form water. If the oxygen supply is cut off, the electrons and hydrogen protons cease to flow through the electron transport system. If this happens, the proton concentration gradient will not be sufficient to power the synthesis of ATP. This is why we, and other species, are not able to survive for long without oxygen!
by substrate-level
phosphorylation
by substrate-level
phosphorylation
by oxidative phosphorylation, depending
on which shuttle transports electrons
from NADH in cytosol
About
36 or 38 ATP
Maximum per glucose:

8. Anaerobic Respiration (fermentation)
Require the energy-carriers formed by glycolysis
Alcholic fermentation
Lactic Acid fermentation

9. Alcoholic Fermentation
Performed by yeast cells
If NADH can’t dump e- into ETC, it dumps them back into pyruvate; making it the electron acceptor!
NAD+ is restored and recycles back into glycolysis  yielding only 2 ATP molecules
Pyruvate will eventually become ethanol (which is an alcohol, hence alcoholic fermentation… DUH!)

10. Alcoholic Fermentation
Alcoholic fermentation is similar to lactic acid fermentation.
glycolysis splits glucose and the products enter fermentation
energy from NADH is used to split pyruvate into an alcohol and carbon dioxide
NADH is changed back into NAD+
NAD+ is recycled to glycolysis

11. Lactic Acid Fermentation
Occurs in muscle cells
Similar to alcoholic fermentation where pyruvate becomes the final electron acceptor
Pyruvate is converted to lactic acid

12. Lactic Acid Fermentation
Lactic acid fermentation occurs in muscle cells.
glycolysis splits glucose into two pyruvate molecules
pyruvate and NADH enter fermentation
energy from NADH converts pyruvate into lactic acid
NADH is changed back into NAD+

13. Energetics of Respiration
Aerobic vs. Anaerobic: Which is more efficient?
Aerobic: yields 38 ATP per glucose molecule
Anaerobic: yields 2 ATP per glucose molecules
Anaerobic is not as efficient, but still allows you to live without oxygen

14. Alternative Food Molecules
Fats and proteins can change form that can enter normal respiration pathways
Fats
Glycerol enters glycolysis
Fatty acids into acetyl-CoA
Proteins
Deaminated, remainder enters
at various points in the chain