3.4c Aerobic Cellular Respiration: Intermediate Stage & 3.4d Aerobic Cellular Respiration; Citric Acid Cycle & 3.4e Aerobic Cellular Respiration: The Electron Transport System

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Intermediate Stage (definition)

The 'link' between glycolysis and the citric acid cycle.

Intermediate Stage (catalyzed by)

Pyruvate dehydrogenase (a multienzyme complex).

Pyruvate dehydrogenase (requirements)

Pyruvate, Coenzyme A (CoA)

Pyruvate dehydrogenase (products)

Acetyl CoA, CO2, 2H+, 2e-

Decarboxylation (definition)

Release of CO2 (from pyruvate).

Acetyl CoA (definition)

A two-carbon molecule with CoA attached

Acetyl CoA (fate)

Enters the citric acid cycle.

2H+, 2e- (fate)

Transfer to NAD+ to form NADH and H+

Intermediate stage (repeateD)

2 timeS

Intermediate stage (products)

2 acetyl CoA, 2 NADH

Explain the enzymatic reaction involving pyruvate dehydrogenase in the intermediate stage - where it occurs, if the process is aerobic or anaerobic, the net chemical reaction, and the net energy transer.

Inside the mitochondria, aerobic process, net chemical reaction = 2 acetyl CoA and 2 NADH, net energy transfer 2NADH

Citric acid cycle (definition)

A cyclic metabolic pathway that occurs in the matrix of mitochondria during which energy in the bonds of acetyl CoA is transferred to form ATP, NADH, and FADH.

Citric acid cycle (requirements)

9 enzymes

Citric acid cycle step 1 (reactant)

acetyl CoA + oxaloacetic acid (OAA)

Citric acid cycle step 1 (product)

Citrate (citric acid)

Citric acid cycle step 2-3 (reactant)

Citrate

Citric acid cycle step 2-3 (products)

Citrate isomer

Citric acid cycle step 4-5 (products)

NADH, attachment of CoA to pyruvate

Citric acid cycle step 4-5 (enzyme)

2 hydrogenase enzymes

Citric acid cycle step 6 (action)

removal of CoA, substrate level-phosphorylation

Citric acid cycle step 6 (product)

ATP

Citric acid cycle step 7 (enzyme)

dehydrogenase

Citric acid cycle step 7 (product)

FADH2

Citric acid cycle step 8 (action)

removal of water

Citric acid cycle step 9 (enzymE)

DehydrogenasE

Citric acid cycle step 9 (product)

NADH, oxaloacetic acid (regenerated)

Citric acid cycle (initial substrate)

Acetyl CoA

Citric acid cycle (final products)

2(CO2), CoA

Citric acid cycle (net transfer energy)

1 ATP, 3 NADH, 1 FADH2

Formation of ATP

1 ATP (step 6 - substrate level phosphorylation)

Formation of NADH

3 NADH (step 4, 5, 9 - acetyl CoA)

Formation of FADH2

1 FADH2 (step 7 - acetyl CoA)

Why is the enzymatic pathway of the citric acid cycle considered to be a cycle?

The enzymatic pathway of the citric acid cycle is considered a "cycle" because it begins and ends with oxaloacetic acid.

Citric Acid Cycle (repeatED)

2 timES

Citric Acid Cycle (high energy products from one glucose molecule)

2 ATP, 6NADH, 2 FADH2

Citric Acid Cycle (regulation location)

Citrate synthetase

Citric Acid Cycle (regulation method)

Negative feedback

Citric Acid Cycle (regulation decrease)

Increase in NADH, ATP, & pathway intermediates.

Citric Acid cycle (regulation increase)

Decrease in NADH, ATP, & pathway intermediates.

Glucose digestion (waste)

6 CO2 molecules

Anaerobic cellular respiration (products)

2 ATP, 2NADH

Aerobic cellular respiration - the intermediate stage (products)

2 NADH

Aerobic cellular respiration - the citric acid cycle (products)

2 ATP, 6 NADH, 2 FADH2

Summarize the metabolic pathway of the citric acid cycle - where it occurs, if the process is aerobic or anaerobic, the net chemical reaction, and the net energy transfer

Matrix of the mitochondria; aerobic; net chemical reaction = 4 CO2, 6 H2O; 2 ATP, 6 NADH, 2 FADH2.

What energy molecules are produced from the chemical breakdown of glucose during each of the three steps of cellular respiration?

2 ATP, 2 NADH; 2 NADH; 2 ATP, 6 NADH, 2 FADH2.

Electron transport chain (definition)

The series of the electron carriers that catch electrons and pass them from one to the other in a series.

ETS Step 1 (Definition)

Electrons are transferred from coenzymes NADH & FADH2 to O2

ETS Step 1 (chemical equation)

O2 + 4e- + 4(H+) -> 2(H2O)

ETS Step 2 (definition)

Proton gradient is established

ETS Step 2 (action)

e- "falling" kinetic energy used by H+ pumps to move H+ from mitochondrial matrix into the outer compartment

ETS Step 3 (definition)

Proton gradient is harnessed to form ATP.

ETS Step 3 (action)

ATP synthetase transports H+ down its concentration gradient across the inner membrane.

Electron transport system (ATP formation type)

Oxidative phosphorylation

Oxidative phosphorylation (why?)

O2 is the final e- acceptor in the process of ATP phosphorylation.

What is the importance of NADH and FADH2 in energy transfer?

NADH and FADH2 are coenzymes that assist in energy transfer by catching and releasing energy (H+ and e-) at key points in the processes.

What are the three primary steps that take place in the electron transport system?

[1] NADH, FADH2 releases 3 H+, 3 e- to two O2, 2H2O form; [2] H+ is powered UP, into the outer compartment; [3] ATP synthase pushes H+ back into the matrix and uses its kinetic energy to perform oxidative phosphorylation on an ATP.

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