CELLULAR RESPIRATION

I. General InfoA. Definition: Cellular respiration is

the break down of food to get energy (ATP)

B. Enzymes control every step of this process

C. All living things respireD. Overall chemical equation:C6H12O6 + 6O2 —> 6CO2 + 6H2O + 36 ATP

From Food to ATP

II. Functions of ATPA. Chemical work –supplies energy needed

to make macromoleculesB. Transport work –supplies energy to

transport substances across the cell membrane.

C. Mechanical work –supplies energy to allow muscle contraction, separation of chromosomes etc.

III. Respiration Pathways

A. Food is broken down and energy is released in a three stage process1. Glycolysis

2. Kreb’s Cycle

3.Electron Transport Draw Fig. 9-2, pg. 222

Glucose(C6H1206)

+Oxygen

(02)

GlycolysisKrebsCycle

ElectronTransport

Chain

Carbon Dioxide

(CO2)+

Water(H2O)

Cellular Respiration

IV. GlycolysisA. Takes place in the cytoplasm of a cell.B. Does not require oxygen.C. Two ATP molecules are formed.D. Summary: Glucose (has 6 carbons) is

broken down into 2 pyruvic acid molecules (each has 3 carbons)

E. Chemical overview

Glucose

To the electron transport chain

2 Pyruvic acid 2 Pyruvic acid

DRAW FIG 9-3, pg. 223

What does anaerobic mean?A. When oxygen is not present, glycolosis is

followed by fermentation (2 types)1. Alcohol Fermentation

a) In yeast

CH3—CH2OH +

Pyruvic AcidEthanol

O2

b) ATP is produced and NADH is converted to

NAD+ allowing glycolysis to continue

V. Anaerobic Pathways

CO2 + NAD++ NADHCH3—C—COO

O

2. Lactic Acid Fermentation (feel the burn!)

a) Lactic acid is produced in muscles of birds and mammals when the body can’t supply enough O2 to tissues

b) Regenerates NAD+ so glycolysis can continue

c) Oxygen debt: the amount of O2 required to convert lactic acid back to pyruvic acid.

Glucose Pyruvic acid Lactic

acid

O2

Glycolysis Lactic Acid Fermentation

DRAW FIG. 9-4,pg. 225

VI. MitochondriaA. Double membrane

organelleB. Central cavity known

as matrix C. Inner membrane folds

known as cristae Draw Fig. 9-1, pg

221

VII. Krebs Cycle (Citric Acid Cycle)

A. Requires oxygen.B. Takes place in the mitochondrial matrix.C. 2 ATP molecules are generated.D. Pyruvic acid (made during glycolysis) is

broken down into CO2 in a series of energy-extracting reactions.

E. High-energy electrons are generated and accepted by electron carriers (NAD+ and FAD)

F. Requires an intermediate step before the cycle can begin…

G. Intermediate Step

1. One C atom from a pyruvic acid molecule becomes part of CO2

2. The other two C atoms combine with CoEnzyme A to form Acetyl-CoEnzymeA

3. Then Acetyl-CoEnzyme A enters the Kreb cycle by combining with a 4-carbon compound to form a 6-carbon compound (citric acid)

Draw Kreb’s Cycle

Pg. 227

Why is it called a cycle?

What happens to the high energy electrons carried on FADH2 and NADH?

VIII. Electron Transport Chain

A. High energy electrons from the Kreb’s cycle are transported by NADH and FADH2 to the Electron Transport Chain.

B. On the cristae of the mitochondria, electrons are transferred from one carrier protein to another creating energy.

C. This process produces 32 ATP.D. At the end of the chain an enzyme

combines these “used up” electrons with H+ ions and oxygen to form water.

Electron Transport Chain (Fig 9-7, pg. 228)Electron Transport

Hydrogen Ion Movement

ATP Production

ATP synthase

Channel

Inner Membrane

Matrix

Intermembrane Space

IX. The Big Picture

Glucose

Glycolysis Krebs cycle

Electrontransport

Fermentation (without oxygen)

Alcohol or lactic acid

C6H12O

6

+ 6 O2

+ 6 CO26 H2OCellular Respiration

Photosynthesis

2 32

2

36 ATP

Draw Fig 9-8; pg 229