Chapter 9:Cellular Respiration& Fermentation

Glycolysis & Fermentation

I. Harvesting Chemical EnergyA. Cellular Respiration – the break down of

organic compounds (food, glucose, etc.) in cells to make energy, ATP molecules

C6H12O6 + 6O2 6CO2 + 6H2O + Energy

B. Glycolsysis 1. Biochemical pathway that always starts

cellular respiration!!!2. Does produce a small amount of ATP.3. Other products can follow two other

pathways, depending on whether oxygen is present not.

Glycolysis ATP

Oxygen Absent Oxygen Present

Fermentation(anaerobic) Aerobic

Respiration

ATP

Cellular Respiration Overview

                Carbon

Glucose           Electron   Dioxide

(C6H12O2) → Glycolysis → Krebs → Transport → (CO2)

+       Cycle   Chain   +

Oxygen               Water

(O2)               (H20)

C. Two (2) Types of Cellular Respiration1. Fermentation– respiration without oxygen

– Can also be called anaerobic respiration

2. Aerobic Respiration – respiration with oxygen

II. Glycolysis

A. Basics of Glycolysis 1. glyco: sugar lysis: break up

• Begins to break down glucose & releases a small amount of energy (ATP)

2. Occurs in the cytoplasm.3. All types of cellular respiration begin with

glycolysis!!!!!!!!!!

B. Major events in Glycolysis1. Start with (invest) 1 glucose, 2 NAD+, and 2 ATP

molecules.2. Glucose, a 6-carbon molecule, is split into 2 PGAL,

or glyceraldehyde-3-phosphate, molecules (each a 3-carbon molecule).

3. Hydrogens are transferred from the 2 PGAL molecules to the 2 NAD+ molecules. This produces 2 NADH molecules.

4. 4 ATP molecules are then produced (2 ATP overall). This also produces 2 pyruvic acid molecules.

5. Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.

Glycolysis

III. FermentationA. Basics

1. Also known as Anaerobic Respiration2. Does not make any ATP!3. Does remake NAD+, which goes back through

Glycolysis to make 2 more ATP.

B. 2 Types of Fermentation1. Alcoholic Fermentation

• A CO2 molecule is removed from each pyruvic acid, creating acetaldehyde.

• 2 H+ are removed from 2 NADH to make NAD+.• Acetaldehyde is converted into ethyl alcohol by

gaining the 2 H+.• NAD+ goes back through glycolysis to make

more ATP.

2 ADP 2 P i 2 ATP

Glucose Glycolysis

2 Pyruvate

2 CO22 NAD

2 NADH

2 Ethanol 2 Acetaldehyde

(a) Alcohol fermentation

2 H

Figure 9.17a

2. Lactic Acid Fermentation• 2 H+ are removed from 2 NADH to make NAD+.• Pyruvic acid is converted into lactic acid by

gaining the 2 H+.• NAD+ goes back through glycolysis to make

more ATP.

(b) Lactic acid fermentation

2 Lactate

2 Pyruvate

2 NADH

Glucose Glycolysis

2 ADP 2 P i 2 ATP

2 NAD

2 H

IV. Mitochondria ReviewA. Structure

1. Surrounded by a double membrane2. The 2nd, inner membrane, is highly folded to

increase surface area. Each fold is called a cristae

3. The very interior of the mitochondria is called the mitochondrial matrix.

IV. Cellular Respiration (aerobic)

A. Basics1. Cellular Respiration requires oxygen (O2)!2. Produces nearly 20 times more ATP than

glycolysis alone.3. Begins with Glycolysis, followed by the Kreb’s

Cycle, the Electron Transport Chain, and Chemiosmosis.

B. Glycolysis 1. Converts glucose into 2 pyruvic acids.2. Makes 2 NADH and a net of 2 ATP.3. Occurs in the cytoplasm

C. Pyruvic acid is converted into Acetyl CoA.1. The 2 Pyruvic Acids pass through both

mitochondrial membranes into the mitochondrial matrix.

2. As this happens, the 2 pyruvic acids reacts with a molecule called coenzyme A to form Acetyl CoA.

3. 2 NADH’s and CO2 are produced.

D. Kreb’s Cycle1. Each Acetyl CoA is broken down to make 1 ATP, 3

NADH, and 1 FADH2. 2. 1st product is remade in the last step, so the

Kreb’s Cycle can happen again.3. Remember, there are 2 Acetyl CoA’s, so the

Kreb’s cycle will happen twice.4. Our totals are therefore: 2 ATP, 6 NADH, and 2

FADH2.

NADH1

Acetyl CoA

CitrateIsocitrate

-Ketoglutarate

SuccinylCoA

Succinate

Fumarate

Malate

Citricacidcycle

NAD

NADH

NADH

FADH2

ATP

+ H

+ H

+ H

NAD

NAD

H2O

H2O

ADP

GTP GDPP i

FAD

3

2

4

5

6

7

8

CoA-SH

CO2

CoA-SH

CoA-SH

CO2

Oxaloacetate

E. Electron Transport Chain1. Occurs across the inner membrane of the

mitochondria (cristae).2. H+ ions are released from NADH and FADH2 into

the mitochondrial matrix.3. The electrons in the hydrogen atoms are at a

high energy level! 4. The high energy electrons are passed along a

series of molecules called the Electron Transport Chain.

E. Electron Transport Chain (cont.)5. As the electrons move from molecule to

molecule, they lose some of their energy.6. This energy pumps H+ out of the mitochondrial

matrix, into the space between the two mitochondrial membranes.

7. A high concentration of H+ builds up in this space.

Electron Transport Chain

F. Chemiosmosis1. H+ ions diffuse from the high area of

concentration made in between the 2 mitochondrial membranes to the low are in the matrix.

2. Specifically the H+ ions move through a protein called ATP Synthase.

3. As H+ ions move through ATP Synthase, ATP is made!

4. 32 ATP are made in chemiosmosis.5. The H+ ions then combine with oxygen to form

water.

Electron Transport Chain

Summary of Cellular Respiration

Total ATP made aerobically: 36 ATP’sGlycolysis = 2Kreb’s Cycle = 2Electron Transport Chain = 32