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Chapter 4 Cells and Energy Cellular Respiration

Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration Process by which food molecules are broken down to release energy Glucose and

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Page 1: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Chapter 4 Cells and Energy

Cellular Respiration

Page 2: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Cellular respiration

Process by which food molecules are broken down to release energy

Glucose and other 6-carbon sugars are major sources of energy

Aerobic processes require oxygen Anaerobic processes don’t need oxygen

Page 3: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Releasing energy with O2

process involves 4 steps Glycolysis Converting pyruvic acid to acetic acid Citric acid cycle (Kreb’s cycle) Electron transport chain

Page 4: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Glycolysis

6-carbon glucose breaks down to 2 molecules of pyruvic acid (each with 3-carbons)

No oxygen required Also produces 2H+ ions and 2electrons

that are picked up by 2NAD+ Uses 2ATP and produces 4ATP (net

production of 2ATP) Occurs in cytoplasm

Page 5: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

GlycolysisGlycolysis

Glucose

2ATP2ADP

2PGAL

4ADP + 4P

2NAD+

2NADH + 2H+

4ATP

2 Pyruvic acid

Page 6: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Fermentation

Lactic Acid Pyruvic acid from glycolysis is converted to

lactic acid NADH + H+ is recycled to NAD+

Alcoholic Pyruvic acid from glycolysis is converted to

ethyl alcohol and carbon dioxide NADH + H+ is recycled to NAD+

Page 7: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Fermentation

Lactic acid fermentation occurs in cytoplasm of muscle cells (causes muscle soreness)

Alcoholic fermentation occurs in bacteria and yeast

Both forms occur in the cytoplasm WITHOUT oxygen

Page 8: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Pyruvic acid to acetic acid

2 Pyruvic acids moves from the cytoplasm into the mitochondria

Each pyruvic acid loses a C to CO2 to make acetic acid

2 Acetic acids are combined with coenzyme A to make 2 acetyl-CoA

2H+ and 2 electrons are picked up by NAD+

Page 9: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Pyruvic acid

Outside the mitochondrion

Mitochondrial membrane

Inside the mitochondrion

Pyruvic acid

Intermediate by-product NAD+

NADH + H+

CO2

Coenzyme A

- CoAAcetyl-CoA

Pyruvic AcidPyruvic Acid

Page 10: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Citric acid cycle (Kreb’s cycle)

Each acetyl-CoA enters the cycle and combines with the 4-carbon oxaloacetic acid to make citric acid

Citric acid loses a C to CO2 and releases H+ to NAD+ to become ketoglutaric acid

Ketoglutaric acid loses a C to CO2, stores energy in an ATP and releases H+ and electrons to NAD+ to make succinic acid

Page 11: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Kreb’s continued

Succinic acid releases H+ and electrons to NAD+ and FAD and converted back to oxaloacetic acid

Products of Kreb’s cycle 4 CO2

2 ATP 6 NADH + H+ 2 FADH

Page 12: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

The Citric Acid CycleThe Citric Acid Cycle

(Acetyl-CoA)

Citric acid NAD+

NADH + H+

O= =O(CO2)

NAD+

O= =O

(CO2)ADP +

ATP

FADFADH2

Citric Acid Cycle

NAD+

NADH + H+ Oxaloacetic acid

The mitochondria host the citric acid cycle.

NADH + H+

Page 13: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Electron Transport Chain

All NADH + H+ and FADH produced go to the electron transport chain

Each NADH + H+ produces 3 ATP (30 ATP)

Each FADH produces 2 ATP (4 ATP) Electron transport chain produces a total

of 34 ATP

Page 14: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

The electron transport chainThe electron transport chain

EnzymeElectron carrier proteins

e -

NADH

FADH2

NAD+

FAD

Electron pathway

4H+ + O2

+ 4 electrons

H2O

H2O

ADP + ATP

Inner membrane

Center of mitochondrion

Space between inner and outer

membranes

Page 15: Chapter 4 Cells and Energy Cellular Respiration. Cellular respiration  Process by which food molecules are broken down to release energy  Glucose and

Total ATP production

Net ATP in glycolysis is 2 ATP production in Kreb’s is 2 ATP production in ETC is 34

Total = 38 ATP