Mitochondria + Cellular Respiration

Question 1

Structure of mitochondria

Answer 1

• Two membranes -> outer membrane
• AND inner highly folded membrane
• Mitochondrial matrix inside inner membrane
• Has its own circular DNA, ribosomes and enzymes

Question 2

Function of mitochondria

Answer 2

• Site of aerobic respiration
• Produces ATP -> drive cellular activities and produce heat

Question 3

Equation of aerobic respiration

Answer 3

Glucose (C6H12O6) + Oxygen -> Carbon Dioxide (From Link Reaction & Krebs Cycle) + Water (From oxidative phosphorylation) + ATP

Question 4

1st Stage of Aerobic Respiration

Answer 4

Glycolysis
Location: In the cytosol
Reactants: Glucose, 2NAD+, 2ADP
Products: 2 Pyruvate + 2H2O，2NADH， 2ATP

• No oxygen required!

Question 5

2nd Stage of aerobic respiration

Answer 5

Link Reaction
Location: Across outer mitochondrial membrane
Reactants: Pyruvate, NAD+, Coenzyme A
Products: Acetyl CoA, NADH, CO2

Question 6

3rd Stage of aerobic respiration

Answer 6

Krebs Cycle:
Location: In the mitochondrial matrix
Reactants: Acetyl CoA, 2NAD+, FAD+, GDP
Products: 2NADH, FADH2, GTP (used for oxidative phosphorylation)

• Can only proceed with presence of oxygen
• Products used for ATP (NADH, FADH2)

Question 7

4th Stage of aerobic respiration

Answer 7

Oxidative Phosphorylation
Location: Across inner mitochondrial membrane
Reactants: FADH2, NADH, H+ and O2, ADP
Products: FAD+, NAD+, H2O, ATP

Question 8

Process of electron transport chain in OP

Answer 8

1. Electrons from NADH and FADH2 donated to electron transport chain -> regenerates NAD+ and FAD for earlier stages of cellular respiration
2. Electrons move along transport chain through series of membrane proteins -> Drives protons across inner membrane into intermembrane space -> establishes proton gradient across inner mitochondrial matrix
3. Electrons transferred to final electron accepter Oxygen, forming water
4. Protons flow down concentration gradient through ATP synthase back into inner mitochondrial matrix -> converts ADP to ATP

Question 9

Features of anaerobic respiration

Answer 9

• In the absence of oxygen (No Krebs Cycle or electron transport chain can take place)
• Through glycolysis to produce small amounts of ATP -> regenrates NAD+ through pyruvate conversion

Question 10

Process of anaerobic respiration in yeast and bacteria

Answer 10

Alcohol Fermentation!
Step 1: (Glycolysis)
Reactants: Glucose, 2ADP, 2NAD+
Products: 2 Pyruvate + 2H2O, 2ATP, 2NADH, CO2

2 Pyruvate -> 2 Acetaldehyde

Step 2: (Pyruvate Conversion)
Reactants: 2 Acetaldehyde, 2NADH
Products: 2 Ethanol, NAD+
- Regenerates NAD+ for glycolysis!

Question 11

Process of anaerobic respiration in muscles

Answer 11

Alcohol Fermentation!
Step 1: (Glycolysis)
Reactants: Glucose, 2ADP, 2NAD+
Products: 2 Pyruvate + 2H2O, 2ATP, 2NADH

Step 2: (Pyruvate Conversion)
Reactants: 2 Pyruvate , 2NADH
Products: 2 Lactic Acid, NAD+
- Regenerates NAD+ for glycolysis!

Question 12

Why do we need oxygen for cellular respiration?

Answer 12

• Accumalation of lactic acid increases body pH and is harmful -> will cause protein denaturation etc.
• We cannot convert pyruvate into acetaldehyde like yeast