Respiration Flashcards
1
Q
what is energy from respiration used for?
A
- active transport eg. sodium potassium ion pumps
- secretion
- endocytosis
- anabolism eg. synthesising proteins from amino acids
- DNA replication
- cytoskeleton - movement
2
Q
structure of mitochondria
A
- inner and outer membrane
- gel-like matrix in middle
- inner membrane folds inwards creating cristae
- contain ribosomes and mitochondrial DNA
3
Q
stages of glycolysis
A
- occurs in cytoplasm
Phosphorylation - 2 phosphates from 2 ATP molecules added to glucose to form 1 hexose bisphosphate (6 carbons) and 2 ADP molecules
- hexose bisphosphate splits into 2 triose phosphate
- triose phophate phosphorylated - phosphate added forming triose bisphosphate
Oxidation - triose bisphosphates oxidised (loses H atom) to form 2 pyruvate - catalysed by dehydrogenase
- they each lose both phosphates to ADP forming 4 ATP molecules (net gain of 2)
- hydrogen atom picked up by NAD forming 2 NADH
if oxygen available, 2 pyruvates transported to matrix
4
Q
link reaction stage of respiration
A
- in matrix
- pyruvate decarboxylated (CO2 removed) to give 2C product
- CO2 diffuses out cell as a waste product
- H removed from pyruvate and picked up by NAD making acetate (2C) and NADH
- acetate combines with coenzyme A forming acetyl coenzyme A
- no ATP produced yet
- occurs for each pyruvate moleule so for 1 glucose - 2 acetyl coA produced, 2 NADH and 2 CO2 released
5
Q
Krebs cycle
A
- in matrix
- acetyl coA (2C) combines with oxaloacetate (4C) to form citrate (6C), while coA returns to link reaction
- decarboxylation - now 5C
- oxidation / dehydrogenation - H atom picked up by NAD - NADH
- decarboxylation - 4C
- substrate level phosphorylation - ATP molecule produced
- oxidation / dehydrogenation - 2 H atoms picked up by FAD - FADH2
- oxidation / dehydrogenation - H atom picked up by NAD - NADH , this happens once more
- citrate is now converted back to oxaloacetate
- this occurs twice per 1 glucose molecule
6
Q
oxidative phosphorylation
A
- occurs across inner membrane of mitochondria
- H atoms carried by NADH and FADH2 are oxidised and release H atoms which split into H+ ions and electrons
- electrons pass across 3 electron carriers
- chemiosmosis - energy gained from passing electrons across carriers is used to pump H+ from matrix to space between inner and outer membrane forming electrochemical gradient
- H+ move down grad back to matrix via ATP synthase
- movement drives synthesis of ATP from ADP and Pi
- at the end of the electron transport chain, H+, electrons and O2 combine to form water
- oxygen is the final electron acceptor
7
Q
what happens to electron transport chain if oxygen isn’t present?
A
- it cannot operate as oxygen is the final electron acceptor
8
Q
substrate level phosphorylation
A
- production of ATP when a phosphate group is transferred from a highly reactive intermediate eg. triose bisphosphate
9
Q
how is mitochondria adapted to respiration?
A
- matrix - contains required enzymes and coenzymes - NAD and FAD, oxaloacetate
- outer membrane - contains protein channels and carriers allowing passage of molecules into mitochondria
- inner membrane - impermeable to smal ions (eg. H+ allowing build up of them in intermembrane space), folded - large SA, many electron carriers and ATP synthase embedded in it
10
Q
first step of anaerobic respiration
A
- occurs in cytoplasm
Phosphorylation - 2 phosphates from 2 ATP molecules added to glucose to form 1 hexose bisphosphate (6 carbons) and 2 ADP molecules
- hexose bisphosphate splits into 2 triose phosphate
Oxidation - triose phosphate oxidised (loses H atom) to form 2 pyruvate - catalysed by dehydrogenase
- this generates 4 ATP molecules (net gain of 2)
- hydrogen atom picked up by NAD forming 2 NADH
11
Q
lactate fermentation
A
- in mammals in absence of oxygen
- in cytoplasm
- glycolysis occurs
- NADH gets oxidised by lactate dehydrogenase and transfers H to pyruvate to make NAD and lactate
- NAD then reused in glycolysis to make more ATP
- lactate diffuses into plamsa and transported to liver cells where it’s converted back to pyruvate for the rest of aerobic respiration - requires oxygen
12
Q
why can’t lactate fermentation occur indefinitely?
A
- doesn’t produce enough ATP to maintain processes over a long period of time
- the build up of lactate causes a fall in pH - proteins will denature (enzymes and muscle filaments)
13
Q
oxygen debt
A
- the repayment of oxygen after exercise
- we still breathe heavily after exercise to deal with the lactate build up
14
Q
alcoholic fermentation
A
- in plants and fungi cells eg. yeast
- in cytoplasm
- glycolysis occurs
- CO2 removed from pyruvate to make ethanal - catalysed by pyruvate decarboxylase
- NADH transfers H to ethanal to make ethanol and NAD
- NAD reused in glycolysis
15
Q
how much energy is produced in anaerobic respiration vs aerobic?
A
anaerobic - 2 ATP
aerobic - 32-38 ATP
