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Chapter 4, Metabolism…continued Section 2, Chapter 4 Mitochondria

Section 2, chapter 4

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Page 1: Section 2, chapter 4

Chapter 4, Metabolism…continued

Section 2, Chapter 4

Mitochondria

Page 2: Section 2, chapter 4

Oxidation- transfer of electrons away from a molecule. Glucose is oxidized in cell respiration. Energy from the transfer of e- away from glucose is used to make ATP.

Initial fuel or energy source

Overview of Cell Respiration

ATP = energy currency used by cells

Glucose is broken down to make ATP

Page 3: Section 2, chapter 4

ATP

hydrolysis

ADP

Adenosine Triphosphate (ATP)Currency of Energy for cells

Adenosine Diphosphate (ATP)ATP is converted to ADP by hydrolyzing one of the phosphorus bonds

Cells break down ATP into ADP for cell activity.

Energy is released by hydrolyzing 3 r d phosphate group of ATP

Page 4: Section 2, chapter 4

Cell respiration regenerates ATP supplies by adding a phosphate to ADP

Cells quickly use their ATP supplies for cell activity, so the ATP must be replenished.

Page 5: Section 2, chapter 4

ATP provides energy for cell activity

Cell Respiration regenerates ATP

Figure 4.8

Page 6: Section 2, chapter 4

Cell Respiration

anaerobic respiration (glycolysis)occurs in the cytoplasmdoes not require oxygen

yields 2 ATP per glucose

aerobic respirationoccurs in mitochondria

requires oxygenyields up to 38 ATP per glucose

Page 7: Section 2, chapter 4

Cell Respiration involves 3 reactions

1. GlycolysisGlycolysis is a series of anaerobic reactions that occur in the cytoplasm.

Glucose is broken down into 2 molecules of pyruvic acidOnly 2 molecules of ATP are produced per glucose molecule.

2. Citric Acid Cycle (Kreb’s Cycle)

If oxygen is present respiration continues into the Citric Acid Cycle within the matix of the mitochondrion.

3. Electron Transport ChainAerobic respiration is complete in the electron transport chain.ETC occurs on the inner membrane of the mitochondrion.

Page 8: Section 2, chapter 4

glucose 1. glycolysis 2. citric acid cycle 3. ETCUp to

36 ATP

If O2 available

Without O2

Lactic acid

2 ATP

Overview of Cell Respiration

Page 9: Section 2, chapter 4

mitochondrion

cellglucose

1. Glycolysis (anaerobic )

pyruvic acid pyruvic acid

O2 available

O2 not available

Lactic acid

2. CAC

3. ETC

Overview of Cell Respiration

Page 10: Section 2, chapter 4

Electron Carriers: NADH & FADH2

During respiration electrons are removed from glucose and transported to the ETC by electron carriers.

Energy from the electrons is used to synthesize ATP in the ETC.

NAD+ NADH

glucose

2e- NADH carries 2e- from glucose into the ETC, where its worth 2-3 ATP

FAD FADH2

2e- FADH2 carries 2e- into the ETC, where its worth 2 ATP

2e-

Page 11: Section 2, chapter 4

Glycolysis

Glycolysis breaks down glucose into 2 Pyruvic Acid molecules

Occurs in Cytoplasm of Cell

Anaerobic Reaction (no oxygen required)

Glycolysis Yields 2 ATP (net gain) per glucose2 NADH molecule (worth 2-3 ATP in the ETC)2 Pyruvic Acid molecules

Page 12: Section 2, chapter 4

Phase 2: lysing of glucose

Phase 3

Summary of Glycolysis glucose

ATPATP

ADPADP

pyruvic acidpyruvic acid

2ATP2 ATP

2ADP2ADP

NAD+NAD+

NADH

Phase 1: phosphorylation of glucose

2 phosphates are added to glucose. 2 ATP are hydrolyzed into 2 ADP molecules in this step.

Glucose is split into 2 3-carbon molecules

Phase 3: oxidation of glucose glucose is oxidized into 2 molecules of pyruvic acid

Phase 3 produces 4 ATP, 2 NADH 2 molecules of pyruvic acid.

Phase 2

Phase 1

NADH

Page 13: Section 2, chapter 4

Glycolysis

+ 2 ATP

- 2ATP are used in the first phase

+4 ATP are produced in the third phase

Glycolysis produces a net gain of 2 ATP

The overall products of glycolysis includes:2ATP2 Pyruvic Acids2 NADH (these carry e- to the ETC)

Page 14: Section 2, chapter 4

The rest of cell respiration depends on oxygen availability

pyruvic acid

If O2 is available pyruvic acid enters mitochondria for aerobic respiration.

If O2 is not available pyruvic acid completes anaerobic respiration in the cytoplasm.

Page 15: Section 2, chapter 4

Anaerobic Respiration

The electron carriers (NADH) from glycolysis cannot enter into the ETC if oxygen is not available.

Without oxygen NADH donates its electrons to pyruvic acid, forming Lactic acid.

pyruvic acid

NADH NAD+

lactic acid

2e-

2e-

This replenishes NAD+ supplies, so they can be used to remove electrons from additional glucose molecules.

Page 16: Section 2, chapter 4

Anaerobic Respiration

During exercise when there isn’t sufficient O2 for aerobic respiration, lactic acid (Lactate) accumulates in the cells.

Without O2, Lactic acid builds up as glucose is burned

Page 17: Section 2, chapter 4

Anaerobic respiration yields only 2 ATP per glucose, but it provides cells with a quick source of energy; for exercise

Once oxygen is available (eg after exercise), then Lactic Acid is converted back to glucose by the liver

Anaerobic Respiration

Oxygen debt is the amount of O2 required to convert the lactic acid back to glucose after exercise.

End of section 2, chapter 4