Cellular respiration

Cellular Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (as ATP)

ATP ADP + P

Glycolysis

Phase 1

“glucose breaks”Occurs in cytoplasmEnergy Investm

ent Phase.

PHOSPHORYLATION – ATP invested for activation. (This destabilizes the glucose molecule slightly.)

Destabilized form of glucose.

Rearrangement of atoms. Fructose-6-phosphate forms. It is an isomer of glucose-6-phosphate.

Destabilized form of glucose.

PHOSPHORYLATION – More ATP is invested, resulting in Fructose 1,6 diphosphate.

Fructose 1,6 diphosphate is broken down into TWO 3 carbon molecules.

Remember: There are TWO product molecules for this and each succeeding step.

Net result: Two glyceraldehyde phosphate molecules.

C C

Energy Yielding Phase

Glyceraldehyde phosphate is oxidized as NAD picks up high energy electrons and hydrogen.

2 NADH are formed. These are high energy molecules.

ATP Production

Phosphate transferred to another carbon.

Water produced.

ATP produced. 2 pyruvate molecules result.

Depending on the organism, and oxygen conditions, the 2 pyruvate molecules go through one of the following: alcohol fermentation, lactic acid fermentation (both anaerobic respiration) or aerobic respiration.

Summary of Glycolysis

Starts with:1 glucose molecule

(C6H12O6)2 ATP

Ends with:2 pyruvate molecules2 NADH4 ATP (Gross), 2 ATP (NET)2 H2O

This process stores a small amount of energy in the bonds of ATP. Where did the energy come from?

Bond energy in GLUCOSE!

ATP production

4 ATP generated - 2 ATP invested 2 ATP net

The Fate of Pyruvate

Phase 2

Depending on the type of organism, and / or oxygen conditions, pyruvate will be broken down via one of the following pathways.

Anaerobic Pathways

Occurs if oxygen is ABSENT.

Pyruvate

Occurs in yeast and some bacteria.

NET ATP production: 2 ATP (from glycolysis)

NADH from glycolysis is recycled so that NAD can be reused in glycolysis.

Occurs in muscles during power activities such as powerlifting and sprinting.

NET ATP production: 2 (from glycolysis)

CONSIDER THIS: WHY DO HUMANS NOT PRODUCE ALCHOHOL IN THEIR MUSCLES WHEN OXYGEN IS ABSENT?

Transition Reactions and Krebs Cycle

If oxygen is present

REMEMBER: There are TWO pyruvate molecules from the original glucose molecule. Everything you see on this page happens TWICE.

TRANSITION REACTIONS: 1. Pyruvate is transported into mitochondria by a carrier molecule.2. Require a “multienzyme complex” which

1. Removes CO22. NAD accepts hydrogen and high energy electrons. NADH

forms.*3. CoA joins acetyl group to make it active.

* NADH carries enough energy to make 3 ATP molecules in the electron transport chain.

Acetyl CoA reacts with oxaloacetate (4C) to produce citrate (6C).

4 C

2 C

6 C

6 C

6 C

Citrate is isomerized to isocitrate.

5 C

6 CIsocitrate loses CO2. NAD picks up hydrogen, electrons and energy from isocitrate.

Which has more energy: isocitrate or ketoglutarate. . .

4 C

5 C1. CO2 is removed.

2. NADH forms.

3. CoA is bonded with a high energy bond.

4 C4 C

ATP forms.

4 C

4 C

FADH2 forms.

Every FADH2 molecule is used to produce 2 ATP molecules in the electron transport chain.

4 C

4 C

4 C

4 C

Another NADH molecule forms and oxaloacetate reforms.

4 C

6 C

2 C

The cycle begins again . . .

Summary of Transition Reactions and Krebs Cycle

Each pyruvate molecule entering the mitochondria goes through the transition reactions and Krebs cycleand results in:

2 CO24 NADH 1 FADH21 ATP

From one glucose molecule:

2 CO2 X 2 = 4 CO24 NADH X 2 = 8 NADH1 FADH2 X 2 = 2 FADH21 ATP X 2 = 2 ATP

The Electron Transport ChainPhase 3

NADH and FADH2 transfer their electrons to carriers in the inner membrane of the mitochondria. Each NADH generates 3 ATP. Each FADH2 generates 2 ATP.

http://www.youtube.com/watch?v=nXop37NVOAY&feature=related

FADH2

FAD

For every NADH that enters the chain, 3 ATP are formed.

For every FADH2 that enters the chain, 2 ATP are formed.

Water is the final electron acceptor. The electrons, hydrogen and oxygen combine to form one water molecule.

Where is all the ATP generated?

x3 x3

x3

x3

x3

x3

x2

x2

x2

Glycolysis- 2 ATP+ 4 ATP

2 NADH x 3 = + 6 ATP

Transition Reactions and Krebs Cycle

-2 ATP*+2 ATP

8 NADH x 3 = +24 ATP2 FADH2 x 2 = +4 ATP

36 ATP