Module 5.2.2 - Respiration

Question 1

What are some features of a mitochondria?

Answer 1

• outer membrane
• inner membrane (respiratory chain)
• cristae ( folds with large SA)
• matrix (Krebs cycle)
• DNA
• ribosomes (70s)
• intermembrane space

Question 2

What is energy used for?

Answer 2

To synthesise large molecules, active transport/conc gradients, mechanical work, thermal energy to maintain body temp

Question 2

What is the word and symbol equation for aerobic respiration?

Answer 2

glucose (C6H12O6) + oxygen (6O2) -> water (6H2O) + carbon dioxide (6CO2)

Question 3

What is ATP?

Answer 3

Adenosine triphosphate
- when phosphate group removed from ATP, 30.5 KJ/mol of energy is released, ADP is formed
- Adenosine monophosphate (AMP) is formed if another phosphate group is removed
- ATP is universal, used by all organisms
- is recycled in the body

Question 4

What happens to excess energy?

Answer 4

Its converted into ATP

Question 5

What is the glycolysis cycle?

Answer 5

1. • Glucose is phosphorylated to make it more reactive by adding 2 molecules of phosphate
     - Hexose bisphosphate is formed
     - 2 ATP molecules are hydrolysed, energy investment phase
2. • Hexose bisphosphate is spilt into 2 molecules of triose phosphate
     - is too unstable as 1 molecule
3. • Each molecule of triose phosphate is oxidised by NAD+ to pyruvate
     - process synthesises 2 molecules of ATP and 1 molecule of reduced NAD per triose phosphate
4. • the fate of pyruvate is dependant on oxygen availability
     - aerobic respiration is enough supply
     - anaerobic respiration if shortage

Question 6

Where does glycolysis take place?

Answer 6

Cytoplasm

Question 7

What type of reaction is ADP + P -> ATP?

Answer 7

Condensation reaction

Question 8

What does phosphorylation mean?

Answer 8

Adding inorganic phosphate group to ADP

Question 8

What are the 2 types of phosphorylation?

Answer 8

Substrate level + oxidative

Question 9

What type of reaction is ATP -> ADP + P?

Answer 9

Hydrolysis reaction

Question 10

What is oxidative phosphorylation?

Answer 10

Electron transport chain
- series of oxidation reaction that release sufficient energy to form ATP from ADP and phosphate

Question 10

What is substrate level phosphorylation?

Answer 10

Glycolysis and Krebs cycle
- single reaction involving direct transfer of a phosphate group from donor molecule to ADP

Question 11

Why must ATP be continuously produced?

Answer 11

Cannot be stored

Question 12

What do enzymes tht are involved in oxidation/reduction reactions need help from?

Answer 12

Coenzymes

Question 13

What are coenzymes?

Answer 13

Organic non-protein molecules, act as cofactors that aid enzymes catalysing biochemical reactions
- NAD, FAD, acetyl coenzyme A (Acetyle CoA)

Question 13

What does OILRIG stand for?

Answer 13

Oxidation Is Lost
Reduction Is Gained

Question 13

What is the link reaction?

Answer 13

• only occurs when oxygen is present
• pyruvate reacts with coenzyme A to form acetyl CoA
• CO2 released in process, NAD+ reduced,
• sugar molecule now contains only 2 carbon atoms
• is decarboxylated and dehydrogenated

Question 14

What is decarboxylation?

Answer 14

Removal of carboxyl group/CO2 from molecule

Question 15

What is dehydrogenation?

Answer 15

Removal of hydrogen from molecule

Question 16

What is the Krebs cycle?

Answer 16

1. • acetyl CoA produced from link reaction
     - acetate removed from CoA and acetyl combines with oxaloacetate to form 6C, citrate
2. • CoA reused in link reaction
3. citrate is decarboxylated (form CO2) and dehydrogenated (release 2 hydrogen that reduce NAD)
   - leaves 5C compound
4. • 5C compound is decarboxylated and dehydrogenated
     - releases CO2 and reducing another NAD
     - 4C compound produced
5. • 4C compound converted into another 4C compound
     - generates ATP molecules by substrate level phosphorylation
     - involves dehydrogenation, 2 hydrogen released as FAD+
     - produces FADH2 and different 4C compound
6. • final 4C intermediate combined with oxaloacetate by dehydrogenation
     - produces molecule of NADH

Question 17

What is the electron transport chain?

Answer 17

• electron (from NADH being oxidised so protein is reduced) gets passed between proteins
• the electron joins to O2 and H+ to make H2O
• H+ ions get pumped through the proteins from the inside of the matrix to the outside intermembrane space
• energy from H+ ions going down conc gradient turns ADP + Pi into ATP

Question 17

How many ATP are made from electron transport chain?

Answer 17

28

Question 18

How many ATP are made from glycolysis, Krebs cycle and ETC?

Answer 18

32
- 2 glycolysis
- 2 Krebs
- 28 ETC

Question 19

What is chemiosmosis?

Answer 19

Conc gradient of H+ ions that generates energy/electricity through ATP syntesase

Question 20

What are the 2 types of pathways in anaerobic respiration?

Answer 20

- lactate fermentation pathway - ethanol fermentation pathway

Question 21

What is the lactate fermentation pathway?

Answer 21

- the products of glycolysis are 2 molecules of pyruvate and 2 NADH and 2 ATP - pyruvate molecules accept the hydrogen atoms from NADH and this is catalysed by enzyme lactate dehydrogenase - pyruvate is reduced and converted to 2 molecules of lactate - the reduced NAD are reoxidised so glycolysis can continue as these coenzymes can accept the hydrogen atoms that are released during oxidation of triose phosphate

Question 22

What is the ethanol fermentation pathway?

Answer 22

- pyruvate made from glycolysis is decarboxylated to from CO2 and ethanal - ethanal is reduced as it gains 2 hydrogen atoms and NADH is reoxidised to form ethanol - the reoxidised NAD is then reused again in glycolysis

Question 23

What is the equation for respiratory quotient?

Answer 23

volume/molecules of CO2 given out --------------------------------------- volume/molecules of CO2 taken in

Question 23

What substrate and RQ does anaerobic respiration have?

Answer 23

Glucose - 1 +

Question 24

What substrates and RQs does aerobic respiration have?

Answer 24

Carbohydrate - 1.0 Proteins - approx 0.9 Lipid - approx 0.7

Question 25

What is a simple respirometer?

Answer 25

- capillary tube with liquid - can add substrate to absorb CO2 - simple to set up - minimal number of connections makes a good seal easier to obtain

Question 26

What is a complex respirometer?

Answer 26

- isn't affected by temp change or air pressure change - can reset easily, repeat measurements - volume increase inside syringe then equals amount of oxygen used - more accurate - right tube control - doesn't involve diameter measurements