BSCI223: Glycolysis/Pyruvate, TCA Cycle & ETC, and Fermentation

UMD | Dr. Erin Tran

Carbohydrate Catabolism: What are the general processes used to produce energy from glucose?

Respiration and Fermentation (Both start with Glycolysis but follow different pathways)

Where does glycolysis occur in?

Cytosol

Glycolysis converts a molecule of glucose into what?

2 molecules of pyruvate

During glycolysis, two types of activated carrier molecules are produced which are?

ATP and NADH (2 of each)

Fill in the Blank: A, B, C, D

Substrate-level phosphorylation; 2 ATP; 2 NADH; 4 ATP

What is the cell input in glycolysis?

Glucose, 2 ATP, 2 NAD+, and 2 P

What is the cell output in glycolysis?

2 NADH, 4 ATP, and 2 Pyruvate

What is the net cell gain (output - input) in glycolysis?

2 NADH, 2 ATP, and catabolism of glucose to pyruvate

What are ways to replenish NAD+?

Aerobic respiration (ETC) and fermentation

Conversion of Pyruvate to Acetyl-CoA produces what?

2 NADH

Tricarboxylic Acid (TCA) Cycle occurs where?

Cytosol

What is generated by the TCA Cycle?

1 ATP, 3 NADH, 1 FADH2

Electrons are passed to electron acceptors, this electron transport occurs on membrane called?

inner membrane

In respiration, electrons are passed to inorganic acceptors. What are the acceptors in Aerobic respiration? Anaerobic respiration?

O2; Nitrogen and Sulfur compounds

Respiration can help restore NAD+ pool by…

donating electrons to an electron transport chain; it also helps create proton motive force

Aerobic Respiration/Oxidative Phosphorylation/Chemiosmosis utilizes the electron transport chain and ATP synthase to generate what?

ATP

During the Electron Chain Transport, what is the energy cash in for 1 NADH?

3 ATP

During the Electron Chain Transport, what is the energy cash in for 1 FADH2?

2 ATP

Fill in the blank

What can be used as a source of energy?

Proteins, Fat, and Sugars

Fermentations occurs in environments that lack what?

Oxygen

With no oxygen, what is alternative way to generate NAD+?

Fermentation

If there is no oxygen, it cannot act as the electron acceptor for the 2 Pyruvate. What acts as the electron acceptor now?

The 2 pyruvate act as their own electron acceptors.

With the 2 Pyruvate becoming their own electron acceptors, what happens to them during fermentation? What are formed?

NADH is oxidized to NAD⁺ by reducing pyruvate (or its derivatives) into compounds such as lactic acid or ethanol. This regenerates NAD⁺, allowing glycolysis to continue.

Does fermentation generate any additional ATP?

No, it does not.

Both aerobic respiration and fermentation of glucose begins with glycolysis, then….

proceeds in separate pathways

What does aerobic respiration depend on?

oxygen electron acceptor

Catabolism of carbohydrates produces intermediates that are necessary for…

Anabolism

Catabolism pathways provide the electron flow that produces _____ for the cell to grow.

energy (ATP)

To summarize, metabolism is…

Initial energy investment followed by energy gain; Depletion of NAD+ stores; NAD+ replenished via ETC or fermentation