1. Glycolysis & Kreb’s Cycle
SBI4U

2. description
Glycolysis occurs in the cytoplasm of plant and animal cells
The main purpose of glycolysis is to break glucose (a 6 carbon sugar) into 2 pyruvate molecules (a 3 carbon molecule)
ATP is required in glycolysis and a total of 2 ATP are converted into ADP + Pi

3. Main reactants
Glucose
ATP
**Note: No oxygen required = anaerobic!

4. Main products
Pyruvate
ATP
NADH

5. overview
Result:
2 pyruvate
2 NADH
Net 2 ATP

6. Details
The glucose is converted through a series of steps to fructose-1,6- diphosphate
Diphosphate ‘aka 2 phosphates’ means that 2 phosphate groups have been added
Where do those phosphates come from? ATP
Therefore, 2 ATP have been used up
Note: enzymes are responsible for all these conversions!

7. The fructose-1,6-diphosphate is then converted to 2 G3P molecules
G3P = glyceraldehyde 3-phosphate
An H atom (carrying 1 proton & 2 electrons) is picked up from each G3P atom (2 are produced) and picked up by a coenzyme/electron carrier NAD+
Since NAD+ is gaining electrons it is REDUCED (GER!) to NADH (a proton H+ is left over)
Each G3P is then converted to a molecule of pyruvate (pyruvic acid), a reaction which requires the use of 2 ATP but produces 4 ATP = net 2 ATP

8. summary

9. Oxidation of pyruvate
Intermediate step between glycolysis and the kreb’s cycle

10. Details Location = Mitochondrial matrix Its aerobic,  requires oxygen
Net 0 ATP
Pyruvate molecules transported from cytoplasm to mitochondria
Converts each pyruvate (3C) into acetyl coenzyme A (2C)
2 CO2 released (1 from each pyruvate)
2 NAD+ reduced to NADH

11. reaction
pyruvate + NAD + CoA  acetyl-CoA + NADH + CO2 (2 pyruvate = 2 NADH and 2 CO2) **CoA = coenzyme A. It is important because it activates pyruvate

12. Kreb’s cycle Acetyl-CoA is ready to enter the Kreb’s cycle
Kreb’s cycle occurs in the mitochondrial matrix
It is aerobic
Net +2 ATP
It is a CYCLE!, begins and ends with the same compound (oxaloacetate)
First compound to form via acetyl-CoA entering is citric acid (citrate)

13. 4-C oxaloacetate (in mitoch.) 6-C citric acid
2-C Acetyl-CoA
enzyme
4-C oxaloacetate (in mitoch.)
6-C citric acid
CoA recycled
2 CO2 molecules split off
4-C succinate (converted back to oxaloacetate)
This cycle turns twice for every glucose molecule oxidized. (remember 1 glucose  2 pyruvate  2 acetyl-CoA  2 turns needed)

14. Result Per acetyl-CoA Per glucose 3 NADH 1 FADH2 1 ATP 2 CO2 6 NADH