Cellular Respiration April 25, 2012

Cellular Respiration

­happens in all living cells. ­is exothermic­H atoms and e­ are removed from glucose (oxidization) and added to oxygen (reduction)­excess energy (40% ­ the rest is waste) is used to synthesize ATP, an endothermic reaction 

The breakdown of glucose for cellular energy.

Cellular Respiration April 25, 2012

Cellular Respiration

Glycolysis1"breaking sugar"­anaerobic (no O2)­cytoplasm

C3C6

or

C3

Fermentation­anaerobic­cytoplasm

Aerobic Cellular Respiration

C2

­aerobic (requires O2)­mitochondria

or

Lactic Acid Fermentation

AlcoholFermentation

2 3

2

Transition Reaction Krebs Cycle

Electron Transport Chain

4

ATP

ATPATP

http://www.youtube.com/watch?v=rGaP9nE8d9k&feature=related

Cellular Respiration April 25, 2012

1 Glycolysis

1 Glucose              2 pyruvate + 2 ATP

Glucose

ATP+

ATP

6 carbons3 carbons

happens in the cytoplasm of all cells

Cellular Respiration April 25, 2012

ATP ADP

ADPATP

6C1 Glycolysis

Glycolysis I endothermic activation ­ requires 2 ATP­breaks glucose into 2 molecules

Glycolysis II exothermic reactions­ each 3 carbon molecule generates 2 ATP, as it is turned into pyruvate, for a total of 4 ATP produced

-2 ATP + 4 ATP = 2 ATP

3C

3CATP

ADP

ATPADP

ATPADP

ATPADP

3C Pyruvate

3C Pyruvate

NADHNAD+

NADHNAD+

http://www.youtube.com/watch?v=3GTjQTqUuOw

Cellular Respiration April 25, 2012

ATP ADP

ADP

6CATP

3C

3CATP

ADP

ATPADP

ATPADP

ATPADP

3C Pyruvate

3C Pyruvate

now what?3 possibilities, depending on the type of cell and conditions

1 Glycolysis

FermentationAnaerobic Respiration

Aerobic Cellular RespirationPyruvate moves into mitochondria of eukaryotic cells if 

sufficient O2 is present

2

2

Alcohol Fermentation

Lactic AcidFermentation

­prokaryotic cells e.g. yeast­produces 2 ethanol, 2 ATP (from glycolysis) and 2 CO2

­eukaryotic cells lacking O2,bacteria, fungi­produces 2 lactic acid and 2 ATP (from glycolysis)

**Both types of fermentation provide means to allow glycolysis to continue, by restoring NADH NAD+.

Cellular Respiration April 25, 2012

Aerobic Cellular Respiration

If there is sufficient O2 in a eukaryotic cell, the pyruvate will move into the mitochondrion for further breakdown.

Remember the mitochondrion???

(enzyme­rich fluid)

intermembrane space [H]+ ion 

reservoir

Cellular Respiration April 25, 2012

• A transport protein moves the pyruvate into the matrix of the mitochondria• Pyruvate oxidation occurs in the matrix

• Pyruvate is oxidized to form Acetyl Co­A, which will enter the Kreb’s Cycle

• CO2 is produced

Transition Reaction

2Matrix

2C Acetyl CoA3C Pyruvate

CO2

NADHNAD+

+

Cellular Respiration April 25, 2012

Krebs Cycle3(Citric Acid Cycle)

CO2

Acetyl CoA

6C

NADH

NAD+

5CCO2

NADH

NAD+

4CADP

ATP

4C

FADH2

FAD

H2O

4C

NADH

NAD+

4C

4C2C

6C (citrate)

For every Acetyl CoA:3 NADH1 FADH21 ATP

NADH and FADH2 carry electrons forward to the next step....

remember x2!

At this point, where have the 6C from glucose gone?

in the matrix....

http://www.youtube.com/watch?v=hw5nWB0xN0Y&feature=relatedKrebs Cycle

Cellular Respiration April 25, 2012

Electron Transport Chain4Wait....what can possibly happen here?Glucose has been totally catabolized into CO2.

Notice we haven't used any O2 yet?and what are all those NADH and FADH2 for...wasn't the point to make ATP????

Cellular Respiration April 25, 2012

Let's look at what we have so far:

ATP ADP

ADPATP

6C3C

3CATP

ADPATP

ADP

3C Pyruvate

3C Pyruvate

NADHNAD+

NADHNAD+

ATPADP

ATPADP

1 Glycolysis2 ATP2 NADH

2C Acetyl CoA3C Pyruvate

CO2

NADHNAD+

+

2 NADH

Transition Reaction

2 x2

Krebs Cycle3 CO2

Acetyl CoA

6C

NADH

NAD+

5CCO2

NADH

NAD+

4CADP

ATP

4C

FADH2

FAD

H2O

4C

NADH

NAD+

4C

4C2C

6C (citrate)

x22 ATP6 NADH2 FADH2

Total ATP = 4Total NADH = 10Total FADH2 = 2

Cellular Respiration April 25, 2012

PhosphorylationRecall:

ADP + Pi → ATP + H2O

http://www.youtube.com/watch?v=Lx9GklK0xQg

The addition of one or more phosphate groups to a molecule.

ATP Cycle

Cellular Respiration April 25, 2012

Chemiosmosis

http://www.youtube.com/watch?v=vYEkDKbyb8Y

http://www.youtube.com/watch?v=_97mnA_kKds&feature=related

Gradients

phosophorylation

Formation of ATP molecules through the movement of hydrogen ions across and electrochemical gradient. (p. 64­65)

Concentration gradient involving 

H+ or e­

Cellular Respiration April 25, 2012

• Occurs in the inner membrane of the mitochondria• Proteins embedded in the membrane help to move hydrogen ions

• NADH and FADH2 (energy­rich electron donors) provide the electrons required• Bring electrons and H+ ions from the Kreb’s cycle in the matrix to the electron transport chain in the cristae• Electrons and H+ ions are removed from NADH and FADH2

The Electron Transport Chain

4

cristae

Cellular Respiration April 25, 2012

• The electron transport chain involves a series of proteins, which are embedded in the inner membrane (cristae) of the mitochondria that help to pump protons across the membrane• These 4 large proteins are referred to as Complexes I – IV p.75

Cellular Respiration April 25, 2012

• Electrons move through the chain in a series of oxidation and reduction reactions • The small amounts of energy released power the proton pumps• The complexes pump H+ ions from the matrix into the intermembrane space• This causes the concentration of H+ ions to build up in the intermembrane space, creating a concentration gradient between the intermembrane space and the matrix 

http://www.youtube.com/watch?v=0LcWbKOW0u8ETC

Cellular Respiration April 25, 2012

In the final steps:

• Oxygen is the final acceptor for electrons, and combines with hydrogen to become water

• H+ ions are allowed to move down the concentration gradient, through another complex called ATP Synthase, back into the matrix• ATP is produced from ADP by the process of phosphorylation

http://www.youtube.com/watch?v=zEmULSTirE8

http://www.youtube.com/watch?v=_97mnA_kKds&feature=related

Cellular Respiration April 25, 2012

Totalsglycolysis

from glycolysis:from respiration:

pyruvate Acetyl CoA:

In the cytoplasm:

In the mitochondria:

krebs cycle:

FADH2

NADH31

NADH

ATP

ATP

ATPATP

ATP

ATPATPATP

NADH

2

1

92

2

31

x2

x2

4

6

ATP

ATP

ATP

4

24

2

36

Cellular Respiration April 25, 2012

Glucose

2 Pyruvate2 CO2

6 H2O

4 CO2

Cellular Respiration April 25, 2012