1- aerobic respiration

What is respiration?

Respiration is the oxidation of glucose to release energy needed for cellular processes.

Why do living cells need respiration?

All living cells require energy for processes such as movement, active transport, and biosynthesis.

What is the word equation for aerobic respiration?

Glucose + oxygen → carbon dioxide + water (+ energy)

Is respiration an exothermic process?

Yes, the oxidation of glucose releases energy, so respiration is exothermic.

Why is energy from respiration not released as heat?

Energy is released in a controlled way and stored as chemical energy in ATP instead of being lost as heat.

What is ATP?

ATP (adenosine triphosphate) is an energy-carrying molecule used by cells.

What are the components of ATP?

ATP is made of adenine, ribose sugar, and three phosphate groups.

How is ATP formed?

ATP is synthesised from ADP and inorganic phosphate (Pi) using energy from respiration.

What reaction forms ATP?

ADP + Pi + energy → ATP

What happens during ATP hydrolysis?

ATP is broken down into ADP and Pi, releasing energy.

Why is ATP a good energy carrier?

It is soluble, releases energy quickly, and provides energy in small, manageable amounts.

Why do cells use ATP instead of glucose directly?

ATP releases smaller amounts of energy that can be used immediately for cellular processes.

Approximately how many ATP molecules are made from one glucose molecule?

Over 30 molecules of ATP can be produced from one glucose molecule.

What is ATP energy used for in cells?

Muscle contraction, active transport, and biosynthesis.

How is ATP used in muscle contraction?

Each step of the muscle cross-bridge cycle requires one ATP molecule.

How is ATP used in active transport?

Each shape change of an active transport protein pump requires one ATP molecule.

How is ATP used in biosynthesis?

Each monomer added to a growing polymer chain requires one ATP molecule.

What enzyme catalyses ATP hydrolysis?

ATPase enzymes catalyse the breakdown of ATP to ADP and Pi.

What is metabolism?

Metabolism is the sum of all chemical reactions taking place in a cell.

What is a metabolic pathway?

A series of enzyme-controlled reactions that occur in a specific order.

What are metabolites?

Metabolites are intermediate compounds formed during metabolic pathways.

Mitochondria & Respiration

Where does most aerobic respiration take place?

In the mitochondria.

What membranes do mitochondria have?

A double membrane: an outer membrane and an inner membrane.

What is the function of the outer mitochondrial membrane?

It contains porins that allow small molecules to pass through.

What is special about the inner mitochondrial membrane?

It is selectively permeable and highly folded into cristae.

What are cristae?

Folds of the inner mitochondrial membrane that increase surface area.

Why do cristae increase the rate of respiration?

They provide a larger surface area for enzymes involved in ATP synthesis.

What are stalked particles?

Enzyme complexes on the inner membrane that synthesise ATP (ATP synthase).

What is the mitochondrial matrix?

The space inside the inner membrane where the Krebs cycle occurs.

What does the mitochondrial matrix contain?

Enzymes, DNA, tRNA, and ribosomes.

Stages of Aerobic Respiration

How many main stages does aerobic respiration have?

Three stages.

What is the first stage of respiration?

Glycolysis.

Where does glycolysis take place?

In the cytoplasm.

Is glycolysis aerobic or anaerobic?

Anaerobic (does not require oxygen).

What is produced in glycolysis?

Pyruvate.

What is the second stage of respiration?

The Krebs cycle.

Where does the Krebs cycle take place?

In the mitochondrial matrix.

What is released during the Krebs cycle?

Carbon dioxide and hydrogen.

What is the third stage of respiration?

The electron transport chain.

Where does the electron transport chain occur?

On the inner mitochondrial membrane.

What is the role of oxygen in respiration?

Oxygen acts as the final electron acceptor and forms water.

What is produced at the end of the electron transport chain?

ATP and water.

When is carbon dioxide released in respiration?

Before oxygen is involved, during the Krebs cycle.

Why is it incorrect to say respiration turns oxygen into carbon dioxide?

Respiration turns glucose into carbon dioxide and oxygen into water.

Why is respiration described as compartmentalised?

Different stages occur in different parts of the cell, allowing better control.