GLYCOLYSIS II &

PYRUVATE OXIDATION

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Intro to cellular respiration

C6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP

* A series of oxidizing reactions converts the energy stored in C-C bonds of glucose to form ATP molecules

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2 reactions:

1. Substrate-level Phosphorylation - Directly produces ATP from ADP + Pi ATP

2. Oxidative Phosphorylation-Indirectly produces ATP through the use of electron carriers

- NAD+ + 2e + 1p NADH + H+

- FAD + 2e + 2p FADH2

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4 steps in the process of cellular respiration:

1. Glycolysis

2. Pyruvate Oxidation

3. Krebs Cycle

4. ETC/Chemiosmosis

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Glycolysis I

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*In Glycolysis I, we have broken glucose down into two 3-carbon molecules called G3P (Glyceraldehyde-3-phosphate)

* We need to transform those molecules into more usable forms

*In Glycolysis II, G3P is converted to PYRUVATE! ** Pyruvate also has 3-carbons

* IMP: we will only talk about 1 set of reactions from now on, although it happens twice (for each G3P molecule)

Glycolysis II

Glycolysis IIStep 1: G3P picks up a Pi and is reduced by NAD+ to form1,3 – BISPHOSPHOGLYCERATE [BPG]

*Note: NAD+ removes a H (2 e, 1p) from G3P to form NADH + H +

Glucose

G6P

F6P

F1,6-BP

DHAPG3P

BPG

Glycolysis IIStep 2: BPG loses a phosphate group to form3-PHOSPHOGLYCERATE [3PG]

*Note: The loss of Pi from BPG from is used to form ATPADP + Pi ATP

Glucose

G6P

F6P

F1,6-BP

DHAPG3P

BPG

3PG

Glycolysis IIStep 3: 3PG rearranges to form2-PHOSPHOGLYCERATE [2PG]

*Isomerization reaction!

Glucose

G6P

F6P

F1,6-BP

DHAPG3P

BPG

3PG

2PG

Glycolysis IIStep 4: 2PG loses 2 H’s and 1 Oxygen as water to formPHOSPHO-ENOL-PYRUVATE [PEP]

Glucose

G6P

F6P

F1,6-BP

DHAPG3P

BPG

3PG

2PG

PEP

Glycolysis IIStep 5: PEP loses a phosphate group, Pi , to formPYRUVATE

*Note: The loss of Pi from PEP from is used to form ATPADP + Pi ATP Glucose

G6P

F6P

F1,6-BP

DHAPG3P

BPG

3PG

2PG

PEP

PYRUVATE

Glycolysis - SUMMARY

- We have converted glucose into two 3-carbon molecules, PYRUVATE that will be further converted

GLYCOLYSIS ENERGY TALLY

ATP USED

ATP produced

NADH produced

FADH2

produced

2 4 2 0

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PYRUVATE OXIDATION *TRANSITION REACTION*

PYRUVATE OXIDATION

* Now that we have produced two molecules of PYRUVATE, we need to break it down even further to obtain all the energy possible from the C-C bonds in glucose.

* Glycolysis occurred in the CYTOPLASM, * Pyruvate oxidation transports the molecules across the inner membrane into the mitochondrial matrix

* There are 3 steps in one transition reaction

PYRUVATE OXIDATION

Steps: 1. CO2 is removed from PYRUVATE to form an acetyl group 2. NAD+ removes 2 e + 1p from pyruvate to form NADH + H+

3. CoA combines to the remaining molecule to form ACETYL-CoA*Co-enzyme A is used to shuttle the acetyl group across the membrane

PYRUVATE OXIDATION - SUMMARY

- Pyruvate, produced from glucose, is converted into a more useful form, ACETYL-CoA, that can be transported across the mitochondrial membrane

PYRUVATE OXIDATION ENERGY TALLY

TOTAL ENERGY TALLY

ATP USED ATP produced NADH produced

FADH2

produced

0 0 2 0

ATP USED ATP produced NADH produced

FADH2

produced

2 4 4 0