Topic 18 - Cellular Respiration

Question 1

Learning Objectives

Answer 1

1. Differentiate between anabolism and catabolism with examples
2. Describe glucose catabolism through the processes of glycolysis, the intermediate reaction, the Krebs Cycle and the Electron Transport Chain
3. Analyse and predict the potential impacts on cellular respiration pathways under metabolic poisoning scenarios

Question 2

Metabolism

Answer 2

The collection of all chemical reactions that occur in the body

Question 3

Anabolism

Answer 3

Form larger molecules from smaller ones
- Building

Question 4

Catabolism

Answer 4

Breaking large molecules into smaller ones
- Destroy

Question 5

ATP

Answer 5

• Recycled by breaking into ADP+Pi
• Cannot be stored
• Holds its energy in the covalent bonds between Phosphates
• Gathered in aerobic/ anaerobic respiration

Question 6

Cellular respiration overview

Answer 6

• Involves Oxidation Reduction reactions (OIL-RIG)
• ## Turns glucose into CO2 via oxidation

Question 7

Other energy carriers

Answer 7

NADH (will be oxidised)
NAD+ (will be reduced)

FADH2 (Will be oxidised)
FAD (Will be reduced)

Question 8

Cellular Respiration pathways

Answer 8

1. Glycolysis
2. Intermediate reaction (link reaction)
3. Kreb Cycle
4. e- Transport Chain
5. ATP Synthesis

Question 9

Glycolysis

Answer 9

• Occurs in cytoplasm
• Anaerobic pathway
• Total net gain of 2ATP
• Series of 10 reactions

1. Glucose is phosphorylated by 2 ATP to form a 6-carbon molecule
2. 6-carbon molecule is turned into 2x 3-carbon molecules
3. 2x NAD+ are reduced into NADH
4. 4x ATP is synthesised from 4 ADP creating 2 pyruvate molecules

Question 10

Intermediate reaction

Answer 10

• Occurs in the matrix
  1. Each pyruvate is decarboxylated and oxydised to form a 2-carbon molecule
  2. NAD+ is reduced and CO2 is produced as a waste product
  3. The 2-carbon molecules bind to Coenzyme A to form AcetylCoA

Question 11

Kreb Cycle

Answer 11

• Occurs in the matrix
• Occurs twice for every glucose initially
• Produces 2xCO2, 3xNADH, 1xFADH2, 1xATP per cycle

1.Acetyl CoA binds to a 4-carbon molecule to form a 6-carbon molecule
2. 6-carbon molecule is decarboxylated forming CO2
3. NAD+ is reduced
4. 5-carbon molecule remains and is decarboxylated and oxidised
5. Another CO2 is released
6. NAD+ and ADP are reduced
7. 4-carbon molecule remains and is oxidised to reduce FAD & NAD+
8. 4-carbon molecule is used at the ‘start’ of the cycle again

Question 12

Electron Transport Chain

Answer 12

• Occurs in the Intermitochondrial membrane
• Uses a protein complex
  1. NADH and FADH2 are oxidised
  2. Protons (H+) are pumped into the intermembrane space and the e- move down the protein complex
  3. e- lose energy moving down the complex as they help pump H+ ions into the membrane space
  4. Oxygen then picks up the e- at the last protein in the complex to form H2O
  5. ATP Synthase occurs

Question 13

ATP Synthase

Answer 13

1. H+ ions are built up in the intermembrane space by the e- transport chain.
2. An eletrochemical gradient is formed
3. H+ flow down concentration gradient through ATP Synthase as the membrane is not permiable to H+
4. ATP synthase uses energy from H+ movement to reduce ADP into ATP
5. 28-34 ATP is synthesised per glucose molecule

Question 14

Aerobic Pathways

Answer 14

• More effective at producing ATP (more ATP for glucose)
• Glycolysis is faster , but only produces 2 net gain ATP compared to 28-34 ATP net gain

3ATP per NADH oxidised
2ATP per FADH2 oxidised