UNIT 3 - AOS 2 - Cellular respiration & Fermentation

Question 1

What are two ways you can measure the rate of cellular respiration.

Answer 1

Measure the amount of CO2 or water that is produced as an output.

Question 2

What are the 3 stages of aerobic cellular respiration.

Answer 2

1. Glycolysis
2. Krebs cycle
3. Electron transport chain

Question 3

Glycolysis

Answer 3

FIRST STAGE IN AEROBIC CELLULAR RESPIRATION
(occurs in cytosol)

• Splits glucose molecule (has 6 carbon) into 2 pyruvate molecules (3 carbon)
• 2ATP and 2 NADH get loaded as glucose breaks down to pyruvate.

Question 5

Krebs cycle

Answer 5

SECOND STAGE IN AEROBIC CELLULAR RESPIRATION
(occurs in the matrix = inner part)

• Makes supply of energy rich coenzymes & CO2
• Pyruvate Oxidation: Pyruvate from glycolysis is converted to Acetyl CoA which enters the Krebs cycle (this occurs before Krebs cycle but can be included as one cycle)

Question 6

Inputs & outputs of Krebs cycle (+ pyruvate oxidation)

Answer 6

INPUTS:
- pyruvate (x2)
- ADP + Pi (x2)
- NAD+ (x2)
- FAD+ (x2)

OUTPUTS:
- CO2 (x6)
- ATP (x2)
- NADH (x8)
- FADH2 (x2)

Question 7

Electron transport chain

Answer 7

THIRD STAGE IN AEROBIC CELLULAR RESPIRATION
(occurs in mitochondria’s inner membrane)

• Releases energy from high energy molecules created in earlier stages
• Needs O2 to work

STEPS:
- Electrons are transferred along enzyme complexes, moving from donors to acceptors in a series of reactions.
- First input of high-energy electrons comes from loaded NADH coenzymes
- FADH2 also donates its high-energy electrons to an acceptor (further down the chain)
- As electrons transfer from one enzyme to next, the energy released is ultimately used to power the prod of ATP from ADP+Pi.
- Final electron acceptor at the end of ETC is oxygen
- O2 accepts electrons and hydrogen ions, forming water = final output.

Question 8

Inputs & Outputs of Electron Transport Chain.

Answer 8

INPUTS:
- O2 (x6)
- ADP + Pi (x 26-28)
- NADH (x10)
- FADH2 (x2)

OUTPUTS:
- H2O (x6)
- ATP (x26-28)
- NAD+ (x10)
- FAD (x2)

Question 9

Anaerobic respiration summary

Answer 9

• Absence of O2 & Net amount of 2 ATP

2 Stages:
- Glycolysis (Producers 2 ATP, 2NADH, 2 Pyruvate)
- Fermentation (converts pyruvate to another molecule & unloads NADH. No ATP produced)

Question 10

Notes about rate and yeild -> aeroboic compared to anaerobic

Answer 10

Anaerobic fermentation, which occurs in the cytosol, produces less ATP per molecule of glucose than aerobic cellular respiration. However, its faster rate of production enables more ATP to be produced per unit of time.

Question 11

Glycolysis -> anaerobic fermentation

Answer 11

• Glucose molecule is the input
• Output is 2 pyruvate molecules, NAD becomes NADH and 2 ATP are produced
• This is the only stage in anaerobic fermentation where ATP is produced

SAME AEROBIC CR

Question 12

Fermentation stage

Answer 12

• Starts with pyruvate molecules
• No energy-rich products are produced
• NAD+ is produced (from NADH) as an output which can be recycled and used in glycolysis

AMINALS:
Lactic acid fermentation -> lactic acid is produced because no oxygen is present

YEAST:
Alcohol fermentation -> Ethanol and CO2 are produced

Question 13

Inputs & outputs of Anaerobic fermentation in ANIMALS

Answer 13

Inputs:
- Glucose
- NAD+ (× 2)
- ADP + Pi (× 2)

Outputs:
- Lactic acid
- NAD+ (× 2)
- ATP (× 2)

Question 14

Inputs and outputs of anaerobic fermentation in yeast

Answer 14

Inputs:
- Glucose
- NAD+ (× 2)
- ADP + Pi (× 2)

Outputs:
- Ethanol
- CO2
- NAD+ (× 2)
- ATP (× 2)

Question 15

Pros and Cons of anaerobic fermentation

Answer 15

PROS:
- No O2& mitochondria
- Faster than aerobic respiration

CONS:
- Only produces 2 ATP
- Cannot be sustained for long periods of time in animals skeletal muscles (due to lactic acid accumulation)