Cellular Respiration

A quick review…

When we eat, we get energy (glucose and other sugars)

Food energy is broken down into usable energy

Energy used to bond phosphate groups to ADP to make ATP

ADP – P ATP

Cellular Respiration

What is cell respiration???

Respiration: the process of breaking down food molecules and changing these into usable energy - ATP

THE GOAL: Create ATP for cells to use Free up electrons—have high energy

Cellular Respiration

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Cellular Respiration

Cellular Respiration

Types of cell respiration

Aerobic Processes: REQUIRE oxygen to take place A lot of energy available (efficient)

Anaerobic Processes: DO NOT require oxygen to take place Get energy quickly (inefficient)

Cellular Respiration

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Glycolysis Involves breaking down 6-carbon

sugars Break sugars into pyruvic acid molecules

3-Carbon molecules

This process is ANAEROBIC No oxygen necessary

Occurs in the cytoplasm of cells

Glycolysis

GlycolysisGlycolysis also creates hydrogen ions

and free electrons The whole point of respiration = high energy

H + ions bond with NAD+ to form NADH + H +

NADH carries electrons and H + ions

This process uses 4 ADP molecule and creates 4 ATP molecules

Glycolysis

GlycolysisTOTAL ATP PRODUCTION:

Glycolysis Step 1 uses 2 ATP molecules

Glycolysis Step 2 converts 4 ADP molecules into 4 ATP molecules

Net ATP production = 2 ATP for every glucose

molecule

Glycolysis When oxygen is present,

aerobic respiration occurs

Happens in the mitochondria

GlycolysisBreaking down Pyruvic Acid…

Occurs in the mitochondria

Pyruvic Acid = 3-carbon compound

Broken down into… 2-Carbon compound—acetic acid Carbon Dioxide

Glycolysis Intermediate Step in Glycolysis

2-Carbon Compound—Acetic Acid Combined with coenzyme A (CoA) Forms compound called acetyl-CoA

This is only an intermediate step—have to move pyruvic acid into Krebs Cycle

Glycolysis

Glycolysis =2 ATP

Cellular Respiration

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Citric Acid (Krebs) Cycle

Produces more ATP and releases more electrons Electrons picked up by NAD + and FAD

Organic carrier molecules

Occurs inside mitochondria Mitochondrial Matrix

Citric Acid (Krebs) Cycle

Acetyl CoA combines with a 4-carbon molecule to form a 6-carbon molecule

Citric Acid

Citric Acid broken down into a 5-carbon compound

NAD + removes electrons (NADH + H +) CO2 released

Citric Acid (Krebs) Cycle

5-carbon compound broken down into a 4-carbon compound

ATP created NAD + removes electrons (NADH + H +) CO2 released

4-carbon compound (oxaloacetic acid) is created

Used to bond with acetyl- CoA to restart cycle

Citric Acid (Krebs) Cycle

Citric Acid Cycle =

2 ATP

Citric Acid (Krebs) Cycle

Cellular Respiration

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Electron Transport ChainWhat is the ETC ?

A series of molecules along which electrons are transferred, releasing energy

Occurs in the mitochondria—wall of mitochondria

Aerobic process Oxygen is involved

Acts as the electron acceptor

Electron Transport Chain

As the electrons are passed between carrier proteins, energy is released ATP is created

Electrons are given up by the carrier molecules NADH and FADH2 ------- NAD + and FAD

Electron Transport Chain

Electron Transport Chain

As the electrons (H + ions) travel down the chain, they bond with oxygen

2 H + + 1 O = water (H2O) Electron acceptor

Carbon is given off as carbon dioxide

Electron Transport Chain

Glycolysis

ETC =34 ATP

Electron Transport ChainA problem exists if there is no oxygen

Anaerobic process

When oxygen is used up, electrons cannot be removed

Traffic jam in the mitochondria

KEY POINT —Electron Transport Chain cannot run without oxygen

Anaerobic Respiration If no oxygen present after glycolysis,

pyruvic acid can still be broken down Fermentation

No ATP made during fermentation

Uses electrons carried by NADH + H +

so that NAD+ can regenerate for glycolysis

Anaerobic Respiration

Anaerobic RespirationTwo types of fermentation

Lactic Acid Fermentation

Alcoholic Fermentation

Glucose2 Pyruvic

Acid2 Lactic

Acid

Glucose2 Pyruvic

Acid2 Ethanol + 2 CO2

Anaerobic RespirationLactic Acid Fermentation

Muscle fatigue When your muscle cells require more energy

than can be produced Lack of oxygen Lactic acid build up = muscle fatigue

When oxygen is present, lactic acid breaks down

Anaerobic Respiration

Anaerobic RespirationAlcohol Fermentation

Occurs in bacteria, plants and most animals

Can you think of a bacteria that is used for fermentation???

Pyruvic Acid is converted into ethanol and carbon dioxide

Anaerobic Respiration

Cellular Respiration

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Cellular Respiration

General Formula

C6H12O6 + 6 O2 6 CO2 + 6 H2O