B12. Respiration (DONE)

Question 1

What are the conditions for aerobic respiration and its product?

Answer 1

Requires presence of Oxygen; Produces carbon dioxide, H2O and high amounts of ATP

Question 2

What are the conditions for anaerobic respiration and its products?

Answer 2

Requires the absence of Oxygen; Produces lactate in animals or ethanol and carbon dioxide in plants and fungi; Produces little ATP as well

Question 3

What are the stages of aerobic respiration and what are the general mechanisms?

Answer 3

Glycolysis - Glucose to pyruvate; Link reaction - Pyruvate to Acetyl Coenzyme A; Krebs cycle - Acetyl CoA to 2H; Oxidative phosphorylation - 2H to H2O, O is terminal molecule

Question 4

Describe the mechanism of glycolysis.

Answer 4

Glucose phosphorylated by 2 ATP forming fructose bisphosphate; Fructose bisphosphate split into 2 triose phosphate; Oxidation of 2 triose phosphate by 2 NAD forming 2 NADH; 2 Triose phosphate dephosphorylated by substrate linked phosphorylation forming 4 ATP; Converted into 2 pyruvate ,

Question 5

What is the net product yield from glycolysis?

Answer 5

2 ATP, 2 NADH, 2 Pyruvate

Question 6

Describe the mechanism of the link reaction.

Answer 6

Pyruvate oxidised by NAD producing NADH and decarboxylated producing CO2, forming acetate; Acetate combines with Coenzyme A forming Acetyl Coenzyme A; Per molecule

Question 7

What is the net product yield from the link reaction?

Answer 7

2 Acetyl coenzyme A; 2 NADH; 2 CO2

Question 8

Describe the general mechanism of the Krebs cycle.

Answer 8

AcetylCoA (2C) combines w/ Oxaloacetate (4C) intermediate forming citrate; Citrate is oxidised by NAD forming NADH, decarboxylated forming CO2; Produced 5C intermediate, decarboxylated forming CO2, oxidised by NAD, FAD then NAD forming FAD2 and 2 NADH and dephosphorylated by substrate linked phosphorylation forming ATP; Reforming to oxaloacetate

Question 9

What is the net product yield from the Krebs cycle per molecule of AcetylCoA?

Answer 9

1 ATP, 2 CO2, 3 NADH, 1 FADH2

Question 10

Why is the krebs cycle significant?

Answer 10

Breaks down macromolecules into smaller ones, pyruvate broken into CO2; Produces H atoms carried by NAD to ETC & provide energy for oxidative phosphorylation; Regenerates 4C intermediate; Source of intermediate compounds used by the cell for important substances, fatty acids, amino acids, chlorophyll

Question 11

What is the importance of phosphorylation of glucose in glycolysis and where does it come from?

Answer 11

Increases molecule reactivity and lowers activation energy for enzyme controlled reactions; phosphate molecules come from hydrolysis of ATP;

Question 12

Describe the structure of mitochondria.

Answer 12

Organelle found in eukaryotic cells; 2 phospholipid membranes; Outer - smooth. permeable to several small molecules; Inner - folded, cristae. less permeable, site of ETC and ATP synthase; Intermembrane space - low pH due to high H+ conc. conc gradient occurs across inner membrane; Matrix - Aq solution within inner membrane. contains ribosomes, enzymes and circular mitochondrial DNA.

Question 13

Which stages produces the most ATP?

Answer 13

Oxidative phosphorylation

Question 14

Define aerobic respiration.

Answer 14

Process of breaking down a respiratory substrate in order to produce ATP using oxygen

Question 15

What’s the equation of glucose respiration?

Answer 15

C6H12O6 + 6O2 => 6CO2 + 6H2O + ATP

Question 16

What are autotrophs?

Answer 16

Organisms that are able to synthesise their own usable carbon compounds from carbon dioxide in the atmosphere through photosynthesis

Question 17

Describe how mitochondria are specialised in active cells.

Answer 17

High conc in in metabolically active cells eg. Muscle, liver and epithelial; Mitochondria have more densely packed cristae, provides greater surface area for proteins and enzymes.

Question 18

Describe the mechanism of oxidative phosphorylation.

Answer 18

NADH & FADH2 donate e- of H atoms to the ETC; e- passed along chain of electron transfer carriers, series of Oxidation-reduction reactions; Energy released as e- flow along chain causes active transport of H+ across inner mitochondrial membrane into inter-memerbanal space; H+ accumulate before they diffuse back into matrix through ATP synthase channels; Chemiosmosis; End of ETC e- combine with oxygen to form H2O

Question 19

What is the importance of oxygen in respiration?

Answer 19

Acts as final acceptor; Terminal molecule

Question 20

What would happen if there was no oxygen during oxidative phosphorylation?

Answer 20

H+ and e- would back up along chain process of respiration would stop due to H+ ions not being removed at the end of the chain

Question 21

Why is energy released in stages during respiration?

Answer 21

The greater the energy that is released in a single step, more of it is released as heat; As energy released slowly, more of it can be harvested for benefit of the organism

Question 22

What are the alternative respiratory substrates to sugars?

Answer 22

Lipids and proteins

Question 23

Describe the mechanism for respiration of lipids.

Answer 23

Lipids are hydrolysed to glycerol and fatty acids; Glycerol then phosphorylated and converted to triose phosphate, entering the glycolysis pathway; Fatty acid is broken down into 2C fragments which are then converted to AcetylCoA and many Hydrogen atoms

Question 24

Why do lipids produce more energy than sugars during respiration?

Answer 24

Large quantity of Hydrogen atoms produced from Fatty acids being converted into AcetylCoA are used to produce ATP during oxidative phosphorylation

Question 25

Describe the mechanism for respiration of proteins.

Answer 25

Hydrolysed to its constituent amino acids. These are deaminated before entering pathway at different points depending on carbon number. 3C - pyruvate; 4 & 5C - intermediates for Krebs.

Question 26

What is the general definition of deamination?

Answer 26

Removal of amino groups of amino acids

Question 27

How do cells respire in low oxygen conditions?

Answer 27

Anaerobic respiration

Question 28

Describe ethanol fermentation.

Answer 28

Pyruvate is decarboxylated to ethanal producing CO2; Ethanal is hydrogen acceptor; NADH is oxidised, forming NAD; Ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase; Ethanol cannot be further metabolised, waste product

Question 29

Describe lactate anaerobic respiration.

Answer 29

Pyruvate is hydrogen acceptor; NADH is oxidised forming NAD by pyruvate; Pyruvate reduced to lactate by enzyme lactate dehydrogenase; Final product lactate cannot be further reduced

Question 30

Describe the metabolisation of lactate

Answer 30

Oxidised back to pyruvate; Channelled into kreb cycle; Needs extra oxygen; Can be converted into glycogen for storage in the liver

Question 31

Why do animals breathe heavier after exercise?

Answer 31

Oxygen debt; Extra oxygen is needed to metabolise, oxidise lactate into pyruvate

Question 32

What is the equation for respiratory quotient?

Answer 32

CO2 produced / O2 consumed

Question 33

What is the respiratory quotient of glucose?

Answer 33

1.0