5.2.2 Respiration
Monday, 1 December 2025 14:02
- Produced ATP for cell division, protein/DNA synthesis, movement, chemical reactions
(anabolic, catabolic), exocytosis
- Aerobic respiration consists of 4 stages: glycolysis (cytoplasm), link (matrix mitochondria),
krebs (matrix mitochondria), oxidative phosphorylation (inner mitochondrial membrane)
- Mitochondria has an outer mitochondrial membrane and inner that folds, folds are called
cristae, inner cytoplasm area = matrix, mitochondrial DNA exists in matrix
- First three are series of reactions, products for final to produce ATP
- Glucose used but other complex organic molecules too (fatty acids, etc)
- Glycolysis starts with one molecule of Glucose (6C) to produce 2 pyruvate, anaerobic
- Stage 1: glucose is phosphorylated with 2Pi from 2ATP, forms hexose bisphosphate and
2ADP. Hexose bisphosphate splits into 2 triose phosphates
- Stage 2: oxidation, triose phosphate is oxidised (loses Hydrogen), 2H+ to 2NAD to produce
2red NAD, 4 ATP produced but 2 used in first stage so net 2
- ATP used for energy, red NAD for oxidative phosphorylation, 2 pyruvates actively
transported into matrix for link
Link reaction:
- Pyruvate is decarboxylated (removal of c in form of CO2), NAD reduced to reduced NAD
(taking hydrogen from pyruvate) to convert it to acetate (2C)
- Add CoA to form acetyl coA
- Occurs twice due to there being 2pyrivates formed from glycolysis
- 2 acetyl coA (go to krebs), 2 CO2 (waste), 2 red NAD (o.p)
- Oxaloacetate (4C) reacts with acetyl group from acetyl coA while coA goes back to link
reaction to be used. Forms citrate (6C)
- Citrate to 5C compound via decarboxylation, and dehydrogenation (combines w NAD to
form red NAD)
- 5C converted to 4C (oxaloacetate): decarboxylation and dehydrogenation (one red FAD and
2 red NAD formed), ATP formed from ADP and Pi from an intermediate compound
(Substrate level phosphorylation).
- Products: coA (used for link), oxaloacetate (reused in cycle), 2CO2 (waste), 1ATP (energy), 3
reduced NAD/1 red FAD (o.p)
Oxidative phosphorylation:
- Energy carried by e- from reduced coenzymes is used to make ATP
- Inner mitochondrial membrane
- H atoms from reduced NAD/FAD released, split into H+ and e-
- E- move at etc (made up of 3 electron carriers, on inner mitochondrial membrane), loses
energy at each carrier.
- Inner membrane folded into cristae, inc SA for max resp
- Lost energy used to pump protons from matrix to inter membrane space, higher conc of h+
in intermembrane space (electrochemical gradient)
- Protons move down conc gradient via ATP synthase back into the matrix, driving the
formation of ATP from ADP+Pi
- Chemiosmosis: ATP production driven by movement of H+ ions across membrane (e-
moving down an etc)
- Chemiosmotic theory in photophosphorylation: atp from etc pumps h+ into lumen from
stroma, back into stroma via atp synthase, producing atp
- At matrix, protons + e- + O2 (from blood) form water
- One glucose molecules forms 32 ATP molecules
Anaerobic resp:
- Alcoholic fermentation or lactate fermentation
- Both occur in cytoplasm, glycolysis start
- Lactate (mammals, some bacteria)
- Glycolysis then
- Red NAD transfers its hydrogen to pyruvate to form lactate and NAD, NAD reused in
glycolysis
- Glycolysis continues even without much o2, small amount ATP still produced
- Can tolerate high lactate levels and low pH for short periods of time, but lactate in excess is
toxic. Liver takes it up converts to glucose in gluconeogenesis
- Alcoholic fermentation (yeast cells, plants)
- Pyruvate decarboxykated to form ethanol, red NAD transfers hydrogen to ethanol to form
ethanol and NAD. Nad reused in glycolysis
- Anaerobic resp produces less atp than aerobic, 2ATP per one glucose, only one energy
releasing stage
- Respiratory substrate: any biological molecule that can be broken down in respiration to
release energy (glcuose, carbs, lipids, proteins)
- Diff resp substrates release diff amounts of energy. High to low (lipids, proteins, carbs)
- Most ATP made from oxidative phosphorylation, required hydrogen from reduced
coenzymes, lipids contain most hydrogen atoms per unit mass followed by rest in order
- RQ (resp quotient) shows what kind of resp substarte an organism is repairing and what
type of resp being used
- RQ = CO2 produced / O2 consumed (can use molar ratio)
- Lipids/proteins have a RQ<1 as more o2 needed to oxidise fats and lipids than to oxidise
carbs
- Normal conditions, human RQ 0.7-1.0, shows some lipids and carbs but no proteins (onky
used unless nothing else)
- High RQ >1, anaerobic + aerobic, short of o2
- Plants may have low RQ as CO2 released in resp is often used in photosynthesis
- Practical variables of respiration: temp (water baths), substrate concentration, use of diff
substrates
- PAG aerobic resp of yeast: known conc and v of substrate solution, known v of buffer
solution keeps pH constant (optimum for yeast), water bath (25) leave for 10 mins for
substrate to stabilise, add known v of yeast suspension stir, adknown v of methylene blue,
seal w bung and shake 10s
- Measuring: start stopwatch, how long it takes to turn blue to colourless, 3x and mean time,
calc mean rate of resp (1/t)
- Methylene blue: redox indicator dye, used instead of electron acceptors in o.p, blue to
colourless
- Anaerobic: known c/v of substrate solution in test tube, known v buffer, water bath 25
stabilise substrate, known v yeast suspension stir, liquid paraffin above to stop O2, gas
syringe bung CO2
- measured at regular time intervals set time (10mins), 3x, mean rate
- Respirometer: rate of aerobic resp by measuring amount of O2 consumed in period of time,
has a manometer (capillary tube w coloured fluid, scale)
- Manometer: coloured fluid added w capillary tube end added to fluid, syringe sets to a
specific level
- Test tube with wood lice on a gauze and KOH underneath (absorbs CO2 so only O2 is
measured), control has same mass but of glass beads on gauze and KOH same v, distance
moved by liquid in manometer in given time measured, volume of O2 found w volume of
tube and distance per min, repeat and mean
- How does liquid move: dec in v of air from O2 consumption, reduced pressure, liquid
moved towards test tube
- Respirometers may also set with oxygen sensor to measure the O2 conc inside chamber at
set intervals, data loggers automatically record w sensor, even into data analysis
software -> conclusions, less human error
Monday, 1 December 2025 14:02
- Produced ATP for cell division, protein/DNA synthesis, movement, chemical reactions
(anabolic, catabolic), exocytosis
- Aerobic respiration consists of 4 stages: glycolysis (cytoplasm), link (matrix mitochondria),
krebs (matrix mitochondria), oxidative phosphorylation (inner mitochondrial membrane)
- Mitochondria has an outer mitochondrial membrane and inner that folds, folds are called
cristae, inner cytoplasm area = matrix, mitochondrial DNA exists in matrix
- First three are series of reactions, products for final to produce ATP
- Glucose used but other complex organic molecules too (fatty acids, etc)
- Glycolysis starts with one molecule of Glucose (6C) to produce 2 pyruvate, anaerobic
- Stage 1: glucose is phosphorylated with 2Pi from 2ATP, forms hexose bisphosphate and
2ADP. Hexose bisphosphate splits into 2 triose phosphates
- Stage 2: oxidation, triose phosphate is oxidised (loses Hydrogen), 2H+ to 2NAD to produce
2red NAD, 4 ATP produced but 2 used in first stage so net 2
- ATP used for energy, red NAD for oxidative phosphorylation, 2 pyruvates actively
transported into matrix for link
Link reaction:
- Pyruvate is decarboxylated (removal of c in form of CO2), NAD reduced to reduced NAD
(taking hydrogen from pyruvate) to convert it to acetate (2C)
- Add CoA to form acetyl coA
- Occurs twice due to there being 2pyrivates formed from glycolysis
- 2 acetyl coA (go to krebs), 2 CO2 (waste), 2 red NAD (o.p)
- Oxaloacetate (4C) reacts with acetyl group from acetyl coA while coA goes back to link
reaction to be used. Forms citrate (6C)
- Citrate to 5C compound via decarboxylation, and dehydrogenation (combines w NAD to
form red NAD)
- 5C converted to 4C (oxaloacetate): decarboxylation and dehydrogenation (one red FAD and
2 red NAD formed), ATP formed from ADP and Pi from an intermediate compound
(Substrate level phosphorylation).
- Products: coA (used for link), oxaloacetate (reused in cycle), 2CO2 (waste), 1ATP (energy), 3
reduced NAD/1 red FAD (o.p)
Oxidative phosphorylation:
- Energy carried by e- from reduced coenzymes is used to make ATP
- Inner mitochondrial membrane
- H atoms from reduced NAD/FAD released, split into H+ and e-
- E- move at etc (made up of 3 electron carriers, on inner mitochondrial membrane), loses
energy at each carrier.
- Inner membrane folded into cristae, inc SA for max resp
- Lost energy used to pump protons from matrix to inter membrane space, higher conc of h+
in intermembrane space (electrochemical gradient)
- Protons move down conc gradient via ATP synthase back into the matrix, driving the
formation of ATP from ADP+Pi
- Chemiosmosis: ATP production driven by movement of H+ ions across membrane (e-
moving down an etc)
- Chemiosmotic theory in photophosphorylation: atp from etc pumps h+ into lumen from
stroma, back into stroma via atp synthase, producing atp
- At matrix, protons + e- + O2 (from blood) form water
- One glucose molecules forms 32 ATP molecules
Anaerobic resp:
- Alcoholic fermentation or lactate fermentation
- Both occur in cytoplasm, glycolysis start
- Lactate (mammals, some bacteria)
- Glycolysis then
- Red NAD transfers its hydrogen to pyruvate to form lactate and NAD, NAD reused in
glycolysis
- Glycolysis continues even without much o2, small amount ATP still produced
- Can tolerate high lactate levels and low pH for short periods of time, but lactate in excess is
toxic. Liver takes it up converts to glucose in gluconeogenesis
- Alcoholic fermentation (yeast cells, plants)
- Pyruvate decarboxykated to form ethanol, red NAD transfers hydrogen to ethanol to form
ethanol and NAD. Nad reused in glycolysis
- Anaerobic resp produces less atp than aerobic, 2ATP per one glucose, only one energy
releasing stage
- Respiratory substrate: any biological molecule that can be broken down in respiration to
release energy (glcuose, carbs, lipids, proteins)
- Diff resp substrates release diff amounts of energy. High to low (lipids, proteins, carbs)
- Most ATP made from oxidative phosphorylation, required hydrogen from reduced
coenzymes, lipids contain most hydrogen atoms per unit mass followed by rest in order
- RQ (resp quotient) shows what kind of resp substarte an organism is repairing and what
type of resp being used
- RQ = CO2 produced / O2 consumed (can use molar ratio)
- Lipids/proteins have a RQ<1 as more o2 needed to oxidise fats and lipids than to oxidise
carbs
- Normal conditions, human RQ 0.7-1.0, shows some lipids and carbs but no proteins (onky
used unless nothing else)
- High RQ >1, anaerobic + aerobic, short of o2
- Plants may have low RQ as CO2 released in resp is often used in photosynthesis
- Practical variables of respiration: temp (water baths), substrate concentration, use of diff
substrates
- PAG aerobic resp of yeast: known conc and v of substrate solution, known v of buffer
solution keeps pH constant (optimum for yeast), water bath (25) leave for 10 mins for
substrate to stabilise, add known v of yeast suspension stir, adknown v of methylene blue,
seal w bung and shake 10s
- Measuring: start stopwatch, how long it takes to turn blue to colourless, 3x and mean time,
calc mean rate of resp (1/t)
- Methylene blue: redox indicator dye, used instead of electron acceptors in o.p, blue to
colourless
- Anaerobic: known c/v of substrate solution in test tube, known v buffer, water bath 25
stabilise substrate, known v yeast suspension stir, liquid paraffin above to stop O2, gas
syringe bung CO2
- measured at regular time intervals set time (10mins), 3x, mean rate
- Respirometer: rate of aerobic resp by measuring amount of O2 consumed in period of time,
has a manometer (capillary tube w coloured fluid, scale)
- Manometer: coloured fluid added w capillary tube end added to fluid, syringe sets to a
specific level
- Test tube with wood lice on a gauze and KOH underneath (absorbs CO2 so only O2 is
measured), control has same mass but of glass beads on gauze and KOH same v, distance
moved by liquid in manometer in given time measured, volume of O2 found w volume of
tube and distance per min, repeat and mean
- How does liquid move: dec in v of air from O2 consumption, reduced pressure, liquid
moved towards test tube
- Respirometers may also set with oxygen sensor to measure the O2 conc inside chamber at
set intervals, data loggers automatically record w sensor, even into data analysis
software -> conclusions, less human error
