#3: Aerobic Cellular Respiration

Question 1

Aerobic Cellular Respiration

Answer 1

Series of enzyme-controlled redox reactions that convert glucose and oxygen into carbon dioxide, water, and ATP

C6H1206 + 6 O2 = 6 CO2 + 6 H20 + ATP

Combustion of glucose is an exothermic reaction

Produces a net yield of 36 ATP

Question 2

Glycolysis

• location
• reactants/products

Answer 2

occurs in the cytoplasm

consists of 10 enzyme-catalyzed reactions that oxidize glucose (6 C) and produces 2 molecules of pyruvate (3 C)

• energy is added (2 ATP) to split glucose into a G3P
• G3P is further oxidized to produce energy (4 ATP), 2 NADH molecules, and form 2 molecules of pyruvate

Question 3

Pyruvate Oxidation

• location
• reactants/products

Answer 3

occurs in the matrix of the mitochondria

converts each molecule of pyruvate into one molecule of acetyl – CoA (needed for the citric acid cycle), 1 molecule of NADH (used in the ETC to make ATP), and one molecule of CO2

2 pyruvate + 2 NAD+ + 2 CoA = 2 acetyl-CoA + 2 NADH + 2 H+ + 2 CO2

Question 4

Citric Acid Cycle
(Krebs cycle)
- location
- reactants/products

Answer 4

occurs in the matrix of the mitochondria

consists of 8 enzyme catalyzed reactions to fully oxidize acetyl-CoA

converts each molecule of acetyl – CoA into 3 molecules NADH (used in ETC to make ATP), 1 molecule of FADH2 (used in ETC to make ATP), 2 molecules of CO2, and 1 molecule of ATP

by the end of cycle, the entire molecule of glucose has been used up and converted into CO2

Question 5

Electron Transport Chain

• location
• reactants/products

Answer 5

occurs in the inner membrane of the mitochondria

uses the NADH and FADH2 to produce 32 molecules of ATP and 6 molecules of H2O

energy released from the oxidation of NADH and FADH2 is used to move H+ into the inner membrane

creates an electro-chemical gradient that is the ultimate source of energy needed to create ATP

Question 6

How does ETC occur?

Answer 6

Electrons are transferred from NADH/FADH2 to O2 through 4 protein complexes and 2 electron shuttles

Protein complexes I, III, IV are ordered with increasing EN to pull electrons along the chain (magnet)

Protein complex II is used to oxidize FADH2 and join the chain

Mobile electron shuttles (Ubiquinone -UQ and cytochrome c - cyt c) are used to move electrons

As the electrons move along chain, energy is released to transport H+ across the membrane creating a concentration gradient

Oxygen is the final acceptor of electrons that pass through the ETC - has highest electronegativity pulling the electrons away from complex IV

Causes complex IV to pull electrons from III, which in turn takes from I

Question 7

Proton-motive force (Chemiosmosis)

Answer 7

As a result of protein complexes pumping H+ across the membrane and creating a gradient (potential energy)

Creates a “proton-motive force” -concentration gradient of H+, electrical-potential charge (H+ repel each other)

Question 8

ATP synthase (Chemiosmosis)

Answer 8

Large multi-protein complex that harnesses this energy to make ATP

Forms a channel which allows H+ back across the membrane causing it rotate in a way to catalyze the hydrolysis of ATP

Reduced Oxygen from the ETC now binds to the H+ coming from ATP synthase to form water