Respiration

Question 1

What is respiration

Answer 1

The process whereby energy stored in complex molecules is used to make ATP

Question 2

What is ATP used for

Answer 2

Metabolic processes
Active transport
Movement
Nerve transmission
Synthesis of materials
Secretion

Question 3

What are the advantages of using ATP

Answer 3

Only one enzyme needed to release energy from ATP
Energy released in small amounts when and where needed
International energy currency

Question 4

What is the structure of the mitochondria

Answer 4

Double membrane to increase surface area
Mitochondrial DNA and ribosomes
Inner membrane = cristae
Many enzymes

Question 5

What is the endosymbiont theory

Answer 5

Some of the organelles in todays eukaryotic cells were once prokaryotic microbes

Question 6

What coenzymes are used in respiration and why are they used

Answer 6

NAD
CoA
FAD
Used in oxidative phosphorylation at the end to produce lots of ATP

Question 7

What are the four main stages of aerobic respiration

Answer 7

Glycolysis
Link reaction
Krebs Cycle
Oxidative Phosphorylation

Question 8

Where does glycolysis occur

Answer 8

cytoplasm

Question 9

What are the products of glycolysis

Answer 9

2 pyruvate molecules, 2 NADH and 2 ATP

Question 10

What happens in glycolysis

Answer 10

• ATP is hydrolysed - glucose undergoes phosphorylation into Glucose-6-P
• Molecule is unstable so undergoes isomerisation into Fructose-6-P
• ATP hydrolysed so Fructose-6-P undergoes phosphorylation into Hexose 1,6-biphosphate
• Hexose splits into 2x triose phosphate
• Substrate level phosphorylation causes condensation of ATP and reduction of NAD by dehydrogenation of TP
• Substrate level phosphorylation of intermediate to produce 2x pyruvate and ATP

Question 11

Where does the Link reaction occur

Answer 11

matrix of mitochondria

Question 12

What happens in the Link reaction

Answer 12

Repeated twice as there are 2 pyruvates
- Pyruvate dehydrogenase removes 2 hydrogens from pyruvate
- NADH, CO2 and acetate(2C) formed
- CoA accepts acetate to form acetyl CoA
- Acetyl CoA moves into Krebs cycle

Question 13

Products of Link reaction

Answer 13

2NADH
2CO2
2 Acetyl CoA

Question 14

What happens in the Krebs cycle

Answer 14

• Acetate leaves CoA and joins oxaloacetate (4C) to form citrate (6C)
• Citrate oxidised and decarboxylated to form 5C by dehydrogenase and decarboxylase, forms NADH and CO2
• 5C oxidised + decarboxylated to 4C, forms NADH and CO2
• 4C undergoes substrate level phosphorylation into another 4C - ATP released
• 2nd 4C converted into 3rd 4C through dehydrogenation - FADH formed
  -3rd 4C converted into oxaloacetate(4C) through dehydrogenation forming NADH
  HAPPENS TWICE AS THERE ARE TWO ACETATES ENTERING CYCLE

Question 15

What are the products of the Krebs Cycleq

Answer 15

4CO2
6NADH
2FADH
2ATP

Question 16

What occurs in oxidative phosphorylation

Answer 16

• NADH is oxidised and donates 2H
• 2H is split into 2e- and 2 protons
• Complex 1 receives electrons - these are passed along electron transfer chain
• Protein carries go from Fe3+ to Fe2+ until it is passed to next protein
• Energy from ETC used for the active transport of protons from matrix to intermembrane space
• FADH is oxidised into 2e- and 2 protons
• electrons received by complex 2, protons pumped to intermembrane space
• H+ conc in intermembrane > than in matrix, electrochemical gradient made and protons move out by chemiosmosis
• Protons travel out through protein channel in ATP synthase - causes synthesis of ATP
• protons join electron that are released from ETC, then reacts with O2 to form water

Question 17

Why is oxygen important in respiration

Answer 17

Driving force of oxidative phosphorylation
without it, the electrochemical gradient between intermembrane space and matrix wouldn’t be as steep as protons wouldnt get removed from matric