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Metabolism. Chapter 24b. Metabolism. The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. Anabolism - build up of complex molecules Catabolism - break down of complex molecules.

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Metabolism

Chapter 24b


Metabolism

  • The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc.

  • Anabolism- build up of complex molecules

  • Catabolism- break down of complex molecules


ORGANIC BUILDING BLOCK MOLECULES

Monosaccharides

Amino acids

Acetates

Nucleotide bases

Fates of Organic Building Blocks in ATP Metabolism

ATP

catabolic processes

energy

energy

anabolic processes

ADP+Pi

Polymers

&

other

energy

rich

molecules

CO2

&

H2O


Cellular Respiration

C6H12O6 + 6O2 + 36ADP + 36Pi

6CO2 + 6H2O + 36ATP


Glycolysis

Acetyl CoA Formation

Krebs Cycle

Electron Transport System

Basic Steps Involved

1

2

3

4


Overview of Glycolysis


Fats

Glycogen

Protein

Other Metabolic Pathways


Glycolysis

P

ATP

ADP

ADP

ADP

NAD+

P

H

P

ADP

ATP

Glucose

NAD+

H

P

2 pyruvate

ATP

NADH

ADP

ATP

ATP

P

ATP

NADH

ADP

P

  • Net:

    • 2 ATP

    • 2 NADH

    • 2 Pyruvate molecules

Cystol


Balance Sheet for Glycolysis

  • Input

    1 Glucose

    2 ADP + Pi

    2 NAD+

  • Output

    2 Pyruvate

    2 ATP

    2 NADH

ADP

ADP

P

P

NAD+

NAD+

ATP

ATP

NADH

NADH


Transition Reaction

2 pyruvates

NADH+

CO2

CoA

NADH

+H+

2 Acetyl CoA’s


Transition Reaction

2 Acetyl CoA’s

CoA

FADH2

Krebs Cycle

2

CO2

FAD

3NAD++3H

NADH

NADH

ATP

NADH

3

ADP+Pi


Krebs Cycle (Citric Acid Cycle)


Balance Sheet for the Transition Reaction and Krebs Cycle

  • Input

    2 Pyruvate

    2 ADP + 2 Pi

    8 NAD+

    2 FAD

  • Output

    6 CO2

    2 ATP

    8 NADH

    2 FADH2


Krebs Cycle

Handles other substrates

Intermediate molecules used: proteins and lipids

Replenishment of intermediates necessary

Hans Krebs (1937): paper originally rejected


Krebs Cycle

Takes 2 complete cycles

8 steps, each with an enzyme


3

Krebs Cycle


Oxidative Phosphorylation

Chemiosmosis

Electrons are transferred from complex to complex and

some of their energy is used to pump protons (H+) into the

intermembrane space, creating a proton gradient.

ATP synthesis is powered by the

flow of H+ back across the inner

mitochondrial membrane through

ATP synthase.


Each Glucose Molecule

CO26

NADH10

FADH22

ATP4


Electron Transport System

CO26

NADH10

FADH22

ATP4

used to make ATP


4

Electron Transport System


Electron Transport System


+Pi


Electron Transport Chain and Oxidative Phosphorylation

  • Electrons are delivered to O, forming O–

  • O– attracts H+ to form H2O


NADH+H+

Electron trans-

port chain

and oxidative

phosphorylation

Glycolysis

Krebs

cycle

FADH2

Enzyme

Complex II

Enzyme

Complex I

Enzyme

Complex III

Free energy relative to O2 (kcal/mol)

Enzyme

Complex IV

Figure 24.9


Electronic Energy Gradient

  • Transfer of energy from NADH + H+ and FADH2 to oxygen releases large amounts of energy

  • This energy is released in a stepwise manner through the electron transport chain


ATP Synthase

  • Two major parts connected by a rod

    • Rotor in the inner mitochondrial membrane

    • Knob in the matrix

  • Works like an ion pump in reverse


Intermembrane space

A rotor in the

membrane spins

clockwise when H+

flows through it down

the H+ gradient.

A stator anchored in

the membrane holds

the knob stationary.

As the rotor spins, a

rod connecting the

cylindrical rotor and

knob also spins.

The protruding,

stationary knob

contains three

catalytic sites that

join inorganic

phosphate to ADP

to make ATP when

the rod is spinning.

ADP

+

Mitochondrial matrix

Figure 24.11


ATP

Net ATP Yield

34 to 36 molecules ATP for every glucose molecule

about 40% efficiency


Transition cycle


Overall ATP Production

Electron Transport System34

Citric Acid Cycle2

Glycolysis2

SUBTOTAL38

NADH Transport into Mitochondrion*-2

TOTAL36


Fermentation (Anaerobic Respiration)


Lactic Acid Fermentation

NAD+

NAD+

NADH

NADH

C

C

C

C

C

C

C

C

C

C

C

C

(Glycolysis)

(Lactic acid fermentation)

Glucose

2 Pyruvate

2 Lactic Acid


Glucose

Anaerobic Respiration

Aerobic Respiration

Pyruvate

no O2

O2

Acetyl CoA

Ethanol or Lactate

Krebs Cycle


INQUIRY

  • What is the end product in glycolysis?

  • What substance is produced by the oxidation of pyruvate and feeds into the citric acid cycle?

  • Name a product of fermentation.

  • What role does O2 play in aerobic respiration?

  • What stage during cellular respiration is the most ATP synthesized?

  • What is chemiosmosis?

  • When NAD+ and FAD+ are reduced what do they form?

  • What are they used for?


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