Cell respiration detailed flashcards (C1.2)

What is glycolysis?

A sequence of enzyme-catalysed reactions in the cytoplasm that break glucose into two pyruvate molecules without requiring oxygen.

Where does glycolysis occur?

The cytoplasm.

Does glycolysis require oxygen?

No, glycolysis is anaerobic.

What is phosphorylation in glycolysis?

The addition of phosphate groups to glucose using ATP, making it more reactive.

Why is phosphorylation important in glycolysis?

It destabilises glucose and prepares it for breakdown.

What is lysis in glycolysis?

The splitting of a 6-carbon glucose molecule into two 3-carbon molecules.

What is oxidation in glycolysis?

The removal of hydrogen from intermediates, with hydrogen accepted by NAD to form reduced NAD.

What is reduced NAD?

NAD that has accepted hydrogen and high-energy electrons.

How is ATP formed in glycolysis?

By substrate-level phosphorylation.

What is the net ATP yield of glycolysis per glucose?

2 ATP.

What are the products of glycolysis per glucose molecule?

Two pyruvate molecules, two ATP (net), and two reduced NAD.

What happens to pyruvate under anaerobic conditions?

Pyruvate is converted to lactate.

What is the role of lactate formation in anaerobic respiration?

To regenerate NAD from reduced NAD.

Why must NAD be regenerated during anaerobic respiration?

So glycolysis can continue producing ATP.

What is the ATP yield of anaerobic respiration per glucose?

2 ATP.

Where does lactate fermentation occur?

In the cytoplasm.

What is the link reaction?

The conversion of pyruvate into an acetyl group that enters the Krebs cycle.

Where does the link reaction occur?

In the mitochondrial matrix.

What happens to pyruvate during the link reaction?

It is decarboxylated, oxidised, and converted into an acetyl group. (goes from 3C→2C)

What is decarboxylation?

The removal of carbon from a molecule.

What happens during oxidation in the link reaction?

Hydrogen is removed from pyruvate and accepted by NAD, forming reduced NAD.

What is an acetyl group?

A 2-carbon molecule formed from pyruvate.

What is the role of coenzyme A?

It transfers acetyl groups to the Krebs cycle.

Which macromolecules can be metabolised to form acetyl groups?

Carbohydrates and lipids.

What is the Krebs cycle?

A cyclic pathway of enzyme-catalysed reactions that oxidise acetyl groups to release energy.

Where does the Krebs cycle occur?

In the mitochondrial matrix.

What molecule combines with the acetyl group to form citrate?

Oxaloacetate.

How many carbons are in citrate?

Six carbons.

How many carbons are in oxaloacetate?

Four carbons.

What happens to oxaloacetate during the Krebs cycle?

It is regenerated so the cycle can continue.

How many decarboxylations occur in the Krebs cycle per acetyl group?

Two.

How many oxidations occur in the Krebs cycle per acetyl group?

Four.

What type of reactions are the oxidations in the Krebs cycle?

Dehydrogenation reactions.

What is produced during oxidation reactions in the Krebs cycle?

Reduced NAD.

Is ATP produced in the Krebs cycle?

Yes, by substrate-level phosphorylation.

What is the electron transport chain?

A series of carriers in the inner mitochondrial membrane that transfer electrons and release energy.

Where is the electron transport chain located?

In the inner mitochondrial membrane.

What donates electrons to the electron transport chain?

Reduced NAD.

What happens to reduced NAD in the electron transport chain?

It is oxidised back to NAD.

How is energy transferred from reduced NAD?

When a pair of electrons is passed to the first carrier in the chain.

What is the proton gradient?

A difference in proton concentration across the inner mitochondrial membrane.

How is the proton gradient generated?

Energy from electron transfer pumps protons into the intermembrane space.

Are protein complex names required for the ETC in IB Biology HL?

No.

What is chemiosmosis?

The synthesis of ATP using energy from a proton gradient.

What enzyme produces ATP during chemiosmosis?

ATP synthase.

How does ATP synthase produce ATP?

By coupling proton flow with phosphorylation of ADP.

What is the role of oxygen in aerobic respiration?

It is the terminal electron acceptor.

What does oxygen combine with at the end of the ETC?

Electrons and protons.

What is produced when oxygen accepts electrons and protons?

Water.

Why is oxygen essential for aerobic respiration?

It allows continued electron flow along the electron transport chain.

What happens to respiration without oxygen?

The electron transport chain stops and reduced NAD cannot be oxidised.