Cells 6

What is cellular respiration?

The process that converts chemical energy in glucose into ATP.

Which organisms perform cellular respiration?

Both plants and animals.

Which organisms perform photosynthesis?

Plants only.

What is ATP?

Adenosine triphosphate, the main energy carrier of the cell.

What are the major energy requirements of cells?

Mechanical work, making new materials, transport work, and maintaining order.

What is an example of mechanical work in cells?

Motor proteins moving vesicles.

Why do cells need energy to make new materials?

For growth and replacement.

What type of transport requires ATP?

Active transport.

Why do cells require energy to maintain order?

To maintain organization and internal conditions.

What does ATP hydrolysis produce?

ADP, inorganic phosphate (Pi), and energy.

What molecule is produced when ATP loses a phosphate group?

ADP.

What type of reaction releases energy from ATP?

Hydrolysis.

What is the ATP hydrolysis equation?

ATP + H2O → ADP + Pi + energy.

Why is ATP important?

It provides controlled release of energy for cellular work.

Does ATP store long-term energy?

No, it transfers energy rapidly and is constantly regenerated.

Where does cellular respiration mainly occur?

In mitochondria.

What is the overall equation for cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy.

What molecule is broken down during cellular respiration?

Glucose.

What gas is consumed during cellular respiration?

Oxygen.

What gas is produced during cellular respiration?

Carbon dioxide.

How many mitochondria can a cell contain?

From 1 to thousands depending on energy demand.

What do mitochondria contain besides membranes?

Their own DNA and ribosomes.

Can mitochondria produce all their own proteins?

No, only some of them.

What are the major structures of the mitochondrion?

Outer membrane, inner membrane, cristae, matrix, and intermembrane space.

How many membranes does a mitochondrion have?

Two.

What is the function of the outer mitochondrial membrane?

Forms the outer boundary.

What is the function of the inner mitochondrial membrane?

Site of oxidative phosphorylation.

What are cristae?

Folds of the inner mitochondrial membrane.

Why are cristae important?

They increase surface area for ATP production.

What is the matrix?

The compartment inside the inner mitochondrial membrane.

What is the intermembrane space?

The space between the outer and inner mitochondrial membranes.

Why are mitochondrial compartments important?

They allow different stages of respiration and proton gradients to occur.

What are the 3 stages of cellular respiration?

Glycolysis, pyruvate oxidation/citric acid cycle, and oxidative phosphorylation.

Where does glycolysis occur?

In the cytosol.

Where do pyruvate oxidation and the citric acid cycle occur?

In the mitochondrial matrix.

Where does oxidative phosphorylation occur?

On the inner mitochondrial membrane.

What happens during glycolysis?

Glucose is split into 2 pyruvate molecules.

How many carbons does glucose contain?

6.

How many carbons are in each pyruvate molecule?

3.

What are the products of glycolysis?

2 ATP and NADH.

What is NADH?

A high-energy electron carrier.

What happens to NAD+ during glycolysis?

It accepts electrons and becomes NADH.

What molecule links glycolysis to the citric acid cycle?

Acetyl CoA.

What happens to pyruvate before entering the citric acid cycle?

It is converted into Acetyl CoA.

What are the outputs of the citric acid cycle?

ATP, NADH, FADH2, and CO2.

What is FADH2?

A high-energy electron carrier.

What is the purpose of NADH and FADH2?

To carry high-energy electrons to the electron transport chain.

What stage produces the most ATP?

Oxidative phosphorylation.

What are the 2 parts of oxidative phosphorylation?

Electron transport chain and chemiosmosis.

Where is the electron transport chain located?

In the inner mitochondrial membrane.

What do NADH and FADH2 deliver to the electron transport chain?

High-energy electrons.

What happens to electrons in the electron transport chain?

They move through protein complexes.

What happens as electrons move through the ETC?

Protons (H+) are pumped across the membrane.

Where are protons pumped during oxidative phosphorylation?

Into the intermembrane space.

What is a proton gradient?

A difference in proton concentration across a membrane.

Why is the proton gradient important?

It stores energy used to make ATP.

Where is the proton concentration highest during oxidative phosphorylation?

In the intermembrane space.

What enzyme produces ATP during chemiosmosis?

ATP synthase.

What drives ATP synthase?

Movement of protons down their concentration gradient.

What reaction does ATP synthase catalyze?

ADP + Pi → ATP.

What is chemiosmosis?

The production of ATP using proton flow through ATP synthase.

Why is the inner mitochondrial membrane functionally important?

It contains ETC proteins and ATP synthase.

Why is compartmentalization important in mitochondria?

It allows proton gradients to form.

What happens if the proton gradient collapses?

ATP production stops.

What is the final electron acceptor in the electron transport chain?

Oxygen.

What is produced when oxygen accepts electrons and protons?

Water.

Why is oxygen essential for oxidative phosphorylation?

Without it the ETC stops.

What stage of respiration occurs in the cytosol?

Glycolysis.

What stages occur inside the mitochondrion?

Pyruvate oxidation, citric acid cycle, and oxidative phosphorylation.

Which stage directly produces most ATP?

Oxidative phosphorylation.

What are the main products of cellular respiration overall?

ATP, carbon dioxide, and water.

What are the main reactants of cellular respiration overall?

Glucose and oxygen.

Why is ATP regeneration essential?

Cells continuously use ATP.

What happens when ATP is used by the cell?

It becomes ADP and Pi.

How is ATP regenerated?

Using energy from cellular respiration.

What type of processes use ATP?

energy-consuming processes.

What type of processes regenerate ATP?

energy-releasing processes.

Which stage of respiration generates a proton gradient?

The electron transport chain.

Which mitochondrial compartment accumulates protons?

The intermembrane space.

What role does ATP play in the cell?

It powers cellular activity.

Why is controlled energy release important?

It prevents explosive release of energy.

What is the sequence of stages in cellular respiration?

Glycolysis → Citric acid cycle → Electron transport chain/oxidative phosphorylation.

Which molecule links the citric acid cycle to the electron transport chain?

NADH.

What is the main function of ATP synthase?

To produce ATP using proton movement.