Week 3- Pre3: Cellular Respiration and Fermentation – P2

Where does Pyruvate Oxidation take place? what does it connect to?

Occurs in the mitochondria (in eukaryotes) or the cytosol (prokaryotes) and connects glycolysis to the citric acid cycle.

explain what is happening in the diagram

explain what is happening in the diagram

Pyruvate Oxidation involves three reactions catalyzed by a multi-enzyme complex. what is this an example of?

Enzyme localization

what is the input/output of pyruvate oxidation

2 pyruvate; 2 Acetyl-coA

What is special about the citric acid cycle?

it finishes the oxidation of glucose: all electrons are in electron carriers

What are the inputs and outputs of the citric acid cycle?

The citric acid cycle takes in 2 Acetyl-CoA and produces 4 CO2, 6 NADH, 2 FADH2, and 2 ATP.

Why is oxygen at the bottom/end of the electron transport chain?

Oxygen serves as the final electron acceptor, allowing the electron transport chain to pull the electrons down the chain. this allows a proton gradient to form (a proton-motive force) , enabling ATP synthesis.

how many protons must pass through the ATP synthase to make 1 ATP?

4

When is fermentation used?

Fermentation is used when oxygen is not available, allowing cells to produce energy under anaerobic conditions by converting glucose into lactate or ethanol.

Per 1 pyruvate:  

_________+ NAD+ + CoA→NADH + H+ + CO2 + ___________

Pyruvate; acetyl-CoA  

what process is this?

Pyruvate oxidation

The citric acid cycle is considered a cycle as it starts and ends with _______

oxaloacetate

__________ + 3 NAD+ + FAD +ADP + phosphate + H2O → ____ + FADH2 + 3 NADH + H+ + 2 CO2 + CoA

acetyl-CoA; ATP

Oxidative Phosphorylation

The synthesis of ATP through the energy released by the transfer of electrons form NADH and FADH2 to O2

What are the two stages of tive Phosphorylation?

the electron transport chain, and chemiosmosis

What is the Electron Transport Chain

A series of protein complexes in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, creating a proton gradient used for ATP synthesis.

Chemiosmosis

An energy-coupling mechanism that uses energy stored in the form of an H+ gradient across a membrane (the proton-motive force) to drive cellular work - provides energy for ATP production by the enzyme

How much ATP is made?

A maximum of 30 or 32 ATP

Efficiency of cellular respiration is ~

34%

What is Phosphofructokinase?

key step of regulation is the enzyme phosphofructokinase of glycolysis, allosterically regulated by ATP, AMP, and citrate

Anaerobic Respiration

Same process of aerobic respiration, O2 is replaced by other molecules such as sulphate, methane, or nitrate

Anaerobic Respiration is ______ efficient than aerobic respiration as these molecules are weaker oxidizing agents than O2

less

What is Fermentation?

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen, often used by yeast and some bacteria.

What is the special characteristic of fermentation?

Skips the electron transport chain, relying solely on substrate-level phosphorylation.

Recycles ______ to ______ via electron transfer to pyruvate

NADH; NAD+