cellular respiration

Question 1

What is the goal of cellular respiration?

Answer 1

To create energy in the form of ATP

Question 2

ATP is used for:

Answer 2

• providing energy for chemical reactions and prcesses
• molecule that carries energy

Question 3

Outline the synthesis of ATP:

Answer 3

• A high energy bond between the second and third phosphate is created
• to create the bond, energy needed comes from breaking down glucose
• energy is stored in the high energy bond

Question 4

Outline the breakdown of ATP:

Answer 4

• high energy bond breaks between second and third phosphate, releasing a phosphate
• energy within the high energy bond is released
• ADP is formed

Question 5

Describe the coenzymes involved in cellular respiration:

Answer 5

NAD+ = unloaded form (not carrying full capacity for protons/electrons)
NADH= loaded form (carrying full capacity)
carry hydrogen ions and electrons

FAD+ = unloaded form
FADH2 = loaded form
carry hydrogen ions and electrons
(carry more hydrogen ions/electrons than other coenzyme)

Question 6

Aerobic cellular respiration vs anaerobic fermentation:

Answer 6

Aerobic:
- occurs in presence of oxygen
- glucose is broken down to produce carbon dioxide, water and ATP
Stages: glycolysis, Krebs Cycle, Electron Transport Chain

Anaerobic:
- occurs in absence of oxygen
- products formed depend on type of organism
- plants an dyeast carry out alcohol fermentation whereas animals carry out lactic acid fermentation

Question 7

Why do we use anaerobic or aerobic? (not needed)

Answer 7

• based on the demand for energy
• if we need energy very quickly, body may not be able to use aerobic respiration as it is more complicated
• if yeast is put into an environment without oxygen, it can do anaerobic fermentation

Question 8

Why is ATP called the universal energy currency of cells?

Answer 8

All organisms have pathways to produce ATP whether oxygen is present or not

Question 9

Why make ATP instead of using glucose?

Answer 9

• glucose has greater chemical energy content but:
• ATP is a more useable form of energy because its energy can be quickly released in a single step
• energy release from glucose is slower and involves a multistep pathway
• direct use of glucose leads to production of excessive heat and waste

Question 10

Word and chemical equation of cellular respiration:

Answer 10

glucose + oxygen —– (energy released) carbon dioxide + water

C6H12O6 + 6O2 —– (ADP + PI —- ATP) ——- 6CO2 + 6H2O

Question 11

What is the total yield of ATP in aerobic respiration and anaerobic fermentation?

Answer 11

anaerobic: 2 ATP per glucose molecule

aerobic: 30 or 32 ATP per glucose molecule

Question 12

Glycolysis: location, inputs, outputs, brief summary

Answer 12

• cytosol/cytoplasm

Inputs: glucose, NAD+, ADP + Pi
Outputs: pyruvate, NADH, ATP (times 2)

• glucose is broken down to release energy and form pyruvate
• energy released is used to join ADP and Pi to create ATP

(hydrogren ions are removed and transfered to unloaded coenzyme NAD+, NADH goes to electron transport chain)

Question 13

Key structure of mitochondria

Answer 13

matrix: fluid component in innermost region, enclosed by inner membrane

cristae- folds formed by inner membrane (think wrinkles of skin)

intermembrane space- region between inner and outer membrane)

Question 14

Krebs cycle:

Answer 14

• matrix

Inputs: pyruvate / acetyl coA (can say either),
NAD+, FAD+, ADP + Pi
Outputs: CO2, ATP (times 2), NADH, FADH2

• pyruvate / acetyl CoA enters mitochondrial matrix to be broken down
• through breaking down Acetyl CoA, coenzymes are loaded

Question 15

Electron Transport Chain:

Answer 15

• cristae

Inputs: NADH, FADH2, ADP + Pi, oxygen
Outputs: NAD+, FAD+, ATP (times 26 OR 28), water

electrons bounce between proteins in electron transport chain, resulting in ATP synthase forming 28 ATP from ADP + Pi

More complicated:
- NADH and FADH move towards cristae and unload protons and electrons
- protons cross the membrane and accumulate in intermembrane space
- electrons bounce between proteins
- H+ pass through ATP synthase, triggering synthesis of ATP
- electrons end up back in matrix
- oxygen collects electrons and hydrogen ions, forming water

Question 16

Ethanol fermentation: organism, location, inputs, outputs, summary

Answer 16

Organisms: yeast, fungi, plants

Location: cytosol

Inputs: pyruvate, NADH
Outputs: ethanol, NAD+, carbon dioxide

Summary:
1. Glycolysis
2.
- Pyruvate is broken down into ethanol
- in breaking down of pyruvate, CO2 is released
- unloading of coenzyme NADH so that NAD+ can be regenerated and glycolysis can continue

Question 17

Why is ethanol and lactic fermentation needed if no ATP is produced?

Answer 17

• to provide a constant source of unloaded enzyme NAD+ for glycolysis

Question 18

Lactic acid fermentation: organism, location, inputs, outputs, summary

Answer 18

Organism: animals
Location: cytosol
Inputs: pyruvate, NADH
Outputs: lactic acid, NAD+

Summary: 1. Glycolysis
2. pyruvate is broken down into lactic acid so that NAD+ can be regenerated and glycolysis can continue

Question 19

Speed, sustainability, inputs and outputs of aerobic respiration vs fermentation

Answer 19

Aerobic:
speed: slow
sustainability: can continue indefinitely
inputs: glucose, oxygen
outputs: water, carbon dioxide

Anaerobic:
speed: fast
sustainability: cannot continue indefinitely due to toxic buildup of lactic acid or ethanol
Inputs: glucose
outputs: lactic acid (animals), ethanol and CO2 (yeast)

Question 20

What is the role of oxygen in aerobic cellular respiration?

Answer 20

To act as a final electron acceptor to keep electrons flowing through the electron transport chain