Ap biology - Unit 3 Cellular energy

Cellular energy is how cells get the power to do everything they need to survive — like moving, dividing, and building stuff.

What is the main energy-carrying molecule in cells?

ATP (Adenosine Triphosphate)

What is the process cells use to make ATP?

Cellular Respiration

Where does most of cellular respiration happen in the cell?

Mitochondria

What are the three main stages of cellular respiration (in order)?

Glycolysis → Krebs Cycle → Electron Transport Chain (ETC)

Where does glycolysis occur?

In the cytoplasm

Does glycolysis need oxygen?

No, it’s anaerobic

What are the products of glycolysis?

2 ATP, 2 pyruvate, and NADH

What gas is required for the Krebs cycle and ETC to work?

Oxygen (O₂)

What waste products are made during cellular respiration?

Carbon dioxide (CO₂) and water (H₂O)

How many ATP are made from one molecule of glucose (total)?

About 36-38 ATP

What happens during anaerobic respiration in humans?

Lactic acid is produced, and less ATP is made

Why is ATP important?

It powers all cell functions (like movement, growth, repair)

What’s the main difference between photosynthesis and respiration?

Photosynthesis stores energy in glucose; respiration releases it from glucose.

What’s the role of ATP synthase?

It makes ATP as protons flow through it during chemiosmosis.

What does energy coupling mean?

Using energy from exergonic reactions to power endergonic reactions.

What’s fermentation and when does it happen?

Anaerobic process that makes ATP without oxygen, producing lactic acid or alcohol.

What’s the final electron acceptor in cellular respiration?

Oxygen (O₂)

What’s produced in the Krebs Cycle?

CO₂, ATP, NADH, FADH₂

What happens in the electron transport chain?

Electrons power proton pumps, creating a gradient; ATP synthase makes ATP; O₂ is the final electron acceptor.

Where does the Krebs Cycle occur?

In the mitochondrial matrix.

What are the inputs and outputs of glycolysis?

Input: glucose → Output: 2 pyruvate, 2 ATP, 2 NADH

Where does the Calvin Cycle take place?

In the stroma of the chloroplast.

Where do the light-dependent reactions occur?

In the thylakoid membranes of the chloroplast.

What is the role of the Calvin Cycle?

It uses CO₂, ATP, and NADPH to make glucose.

What happens during the light-dependent reactions of photosynthesis?

Light splits water to produce O₂, ATP, and NADPH.

What does it mean when an enzyme is denatured?

Its shape changes, so it can’t bind to its substrate or function properly.

What is an enzyme?

A protein that speeds up chemical reactions by lowering activation energy.