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

2. 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
Overview
Respiration starts with glycolysis. This occurs in the cytosol (cytoplasm). 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 (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:

3. Glycolysis
Occurs in the cytoplasm (cytosol)
Refer to handout…

4. Glycolysis

5. Glycolysis
1. Phosphorylate glucose – 2 ATP used up

6. Glycolysis
2. Rearrange molecule to form fructose

7. Glycolysis 3. Phosphorylate again – ATP used up
Diphosphate = bisphosphate

8. Glycolysis 4. Split into two 3-carbon pieces, each containing one P
2 glyceraldehyde 3-phosphate (G3P) or PGAL

9. Glycolysis
5. Add a high-energy phosphate (~ P ) to each piece. NAD+ is reduced to NADH + H

10. Glycolysis
6. Transfer the high-energy phosphate to ADP, making ATP (2 are made)… substrate-level phosphorylation!

11. Glycolysis
7. Rearrange the position of the remaining phosphate

12. Glycolysis
8. Remove H2O, making phosphoenolpyruvate which contains ~ P

13. Glycolysis
9. Transfer high-energy phosphate (~ P ) to ADP, making ATP; 2 ATPs are made
PEP becomes pyruvate

14. Glycolysis Click here to view a different animation
Click here to view a different animation