respiration Flashcards
what are the 4 phases of respiration?
- glycolysis
- link reaction
- krebs cycle
- ETC
where does glycolysis occur?
cytoplasm/cytosol
where does the link reaction occur?
matrix of the mitochondria
where does krebs cycle occur?
mitochondria
where is the ETC?
cristae
how is the outer membrane adapted for function?
contains transport proteins that move pyruvate into the cytosol
how is the inner membrane adapted for function?
contains ETC and ATP synthase
how is the cristae adapted for function?
increased SA:V ratio
how is the intermembrane space adapted for function?
maximises hydrogen gradient
how is the matrix adapted for function?
contains enzymes and suitable pH for krebs
what are the 4 steps of glycolysis?
- phosphorylation
- lysis
- oxidation/dehydrogenation
- ATP formation
which stages are aerobic and anaerobic?
- glycolysis is the only anaerobic stage
- all 4 are in aerobic
what happens in glycolysis?
- glucose is phosphorylated by ATP and forms hexose bisphosphate which is unstable and can’t diffuse out the cell
- 6C hexose bisphosphate is further phosphorylated by loose Pi in cytosol and 2 triose phosphates form
- one H+ is removed from each triose to reduce NAD
- substrate level phosphorylation occurs when energy directly from the sugar forms ATP
- pyruvate forms
- net 4-2 ATP and 2 NADH
what happens in the link reaction?
- oxidative decarboxylation
- occurs twice per glucose molecule
- pyruvate is actively transported to the matrix
- carboxyl group is removed and released as CO2
- hydrogen is also released and accepted by NAD to form NADH
- 2C Acetyl is left which binds to coenzyme A
Acetyl CoA
what happens in the krebs cycle?
- acetyl CoA transfers the acetyl group to a 4C compound to make citric acid
- decarboxylation removes a C atom from 6C citric and forms carbon dioxide and a 5C compound
- oxidation of NAD occurs 3 times and FAD once
- 5C goes to 4C oxaloacetate
what are the end products of glycolysis?
2xNADH
2XATP
what are the end products for the link reaction?
2xNADH
2xCO2
what are the end products for krebs cycle?
6xNADH
2xFADH
4XCO2
2XATP
what happens in oxidative phsophorylation?
- hydrogen carriers (FADH and NADH) are oxidised and release protons and high energy electrons which move to the ETC
- proton motive force and chemiosmosis allows the protons to move through ATP synthase
- ATP is synthesised
why does aerobic respiration not typically yield the full amount of ATP?
- used in active transport of pyruvate and H+ ions
- some energy lost as heat
what is the yield of ATP in aerobic?
38
what is the yield of ATP in anaerobic?
2
what is the product of anaerobic?
lactic acid
suggest why parasites that live in blood are adapted to respire anaerobically?
- oxygen binds to haemoglobin as it has a higher affinity for oxygen
- little oxygen in the blood so must respire anaerobially
what are the three types of respiratory organisms?
- obligate anaerobes
- facultative anaerobes
- obligate aerobes
what is fermentation?
complex organic molecules incompletely broken down into simpler inorganic molecules which results in less ATP produced via substrate level phosphorylation
why does the lack of oxygen prevent the progression of respiration?
no oxygen to act as the final electron acceptor for the electron transport chain
what happens in lactate fermentation?
pyruvate is converted into lactic acid which is a reversible process
describe the process of lactate fermentation.
- reversible
- glucose is broken down incompletely into pyruvate
- 2NAD is reduced to 2NADH and 2 ATP forms
- NADH oxidises with lactate dehydrogenase and the hydrogen is given to the pyruvate form 2 lactic acid
explain why lactate fermentation is not sustainable
- doesn’t produce enough ATP
- low pH affects proteins (muscles) and enzymes
- lactate moves to the liver to become pyruvate an reenters aerobic respiration when oxygen becomes available
what happens in alcoholic fermentation?
pyruvate becomes ethanol
describe the process of alcoholic fermentation
- irreversible process
- pryuvate is converted to ethanal (2C) catalysed by pryuvate decarboxylase
- ethanal accepts a hydrogen ion from NADH and is reduced to form ethanol
- NAD is produced and becomes an electron acceptor
why do beer and wine not contain live yeast?
alcohol disrupts the phospholipid bilayer so it becomes unstable and cells die
what is a respiratory substrate?
a molecule from which energy can be liberated to produce ATP
how are carbs metabolised?
they hydrolyse to monosaccharides and enter glycolysis
how are triglycerides metabolised?
hydrolyses into glycerol and fatty acids (beta oxidation) which are converted into acetyl CoA into krebs
how are proteins metabolised?
hydrolysed into amino acids and enter krebs
why do we respire glucose and not lipids?
- carbs have more oxygen so enter the oxidation process faster
- they can oxidise faster than lipids as lipids have to go through more steps to become acetyl CoA and enter the krebs cycle
what is the equation for respiratory quotient?
vol carbon dioxide produced / vol oxygen consumed
what is the RQ of carbohydrates?
1
what is the RQ of proteins?
0.9
what is the RQ of lipids?
0.7
why is NAD reformed in anaerobic respiration?
needed to keep glycolysis going as there is limited NAD in the cell, and allows some ATP to form
explain why the incomplete breakdown of glucose in anaerobic respiration produces less ATP than aerobic
in glycolysis, only 2 ATP are produced by substrate level phosphorylation as oxygen is not available as the final electron acceptor. as krebs and the ETC do not occur, only 2 ATP is yielded
describe the production of ATP by substrate level phosphorylation
4 ATP molecules are produced in glycolysis when 2 triose phosphate is broken down into 2 pyruvate and the yield is 2 ATP as 2 are used.
1 ATP is yielded in one cycle of krebs when 5C is converted to 4C oxaloacetate
outline the processes involved in the generation of ATP through chemiosmosis
- involves inner membrane and matrix
- hydrogen ions pumped out of matrix into the intermembrane space
- proton gradient is created
- protons diffuse down the concentration gradient through ATP synthase
- ATP synthase produces ATP from ADP + Pi
Using your knowledge of aerobic and anaerobic respiration, explain why overwatering can kill plants
- no aerobic respiration as oxygen isnt present to be the final electron acceptor
- switches to anaerobic
- glycolysis occurs and alcoholic fermentation happens
- pyruvate breaks down into ethanal then ethanol using pyruvate decarboxylase
- only 2 ATP are produced so less active transport of mineral ions into plant so cant produce amino acids and DNA
- water potential in roots is too high so water isnt absorbed so less photosynthesis
