respiration Flashcards
Where does each part of respiration occur in the mitochondria?
*Glycolysis - cytoplasm (anaerobic)
*Link and krebs- mitochondrial matrix
*Oxidative phosphorylation - inner
mitochondrial membrane
Describe the process of glycolysis
- Glucose phosphorylated to glucose phosphate
○ Using inorganic phosphates from 2 ATP - Hydrolysed to 2 x triose phosphate
*Oxidised to 2 pyruvate
○ 2 NAD reduced
○ 4 ATP regenerated (net gain of 2)
Explain what happens after glycolysis if respiration is anaerobic
- Pyruvate converted to lactate (animals & some bacteria) or ethanol (plants & yeast)
- Oxidising reduced NAD → NAD regenerated
- So glycolysis can continue (which needs NAD) allowing continued production of ATP
What is required for pyruvate to be actively transported into the mitochondrial matrix
Oxygen
Describe the link reaction
- Pyruvate oxidised (and decarboxylated) to acetate
○ CO2 produced
○ Reduced NAD produced (picks up H) - Acetate combines with coenzyme A, forming Acetyl Coenzyme A
What is the purpose of Coenzyme A
helps bind acetate- 2C to 4C in Krebs cycle
Describe the Krebs cycle
Acetyl coenzyme A (2C) reacts with a
4C molecule
○ Releasing coenzyme A
○ Producing a 6C molecule that
enters the Krebs cycle
2. In a series of oxidation-reduction
reactions, the 4C molecule is regenerated and:
○ 2 x CO2 lost
○ Coenzymes NAD & FAD reduced
○ Substrate level phosphorylation
(direct transfer of Pi from compound to ADP) → ATP produced
How does 4C regenerate in the kerb cycle
*Citrate (6C) is decarboxylated (releasing CO₂) and dehydrogenated (producing NADH and FADH₂) until a 4C molecule is regenerated.
The final step involves the regeneration of oxaloacetate (4C), which combines with another acetyl-CoA to restart the cycle.
How many products per glucose are created in the kerbs cycle
6 x reduced NAD,
2 x reduced FAD, 2 x ATP and 4 x CO2
How many products per glucose are created in the link reaction
2 x Acetyl Coenzyme A,
2 X CO2 and 2 X reduced NAD
Describe oxidative phospholyration
*reduced coenzymes release hydrogen
*hydrogen splits into protons and electrons
*electrons are transported down the electron carriers
*process releases energy, energy used to transport protons from matrix into intermembrane space
*electron chemical gradient created
*protons move down conc gradient thru ATP synthase
*ADP and Pi phospholyrated
*oxyvgen is trrminal acceptor and accepts electrons and protons to form water as a waste product
Where does anaerobic respiration occur
Cytoplasm
Alternative respiratory substrates
Fatty acids converted to acetyl co a- used in Krebs cycle
Glycerol- triose phosphate- glycolisis/krebs
Amino acid- deamination- 3C into pyruvate and 4C and 5C atoms in krebs cycle (enter respiratory pathways at diff stages depending on number of C)
How is 38 ATP made
G= 2NAD- 6ATP
LR= 2NAD- 6ATP
Krebs- 2 ATP from sub level and 22 ATP (6NADH= 18, 2FADH- 4ATP)
how much atp is produced by 1 NADH and 1 FADH
1 NADH- 3
1 FADH- 2
How do u calculate rate of respiration?
Rate of respiration= volume/ time x mass
Volume of a cylinder calculate by pi x r2
Explain why apparatus must be air tight in respirometer
*prevents air from entering/leaving as it would change volume and pressure
*affecting movement of liquid
What’s the purpose of the CO2 absorber
absorb CO2produced in respiration so volume of oxygen absorbed by organism can be measured
How do respirometers work?
*oxygen used for aerobic respiration
*reduces the volume of oxygen in tube, therefore decreasing the pressure
*CO2 absorbent/ potassium hydroxide (KOH) absorbs CO2
*liquid in connecting tubes moves from higher to lower pressure
*time taken is measured
Describe how a respirometer can be used to measure the rate of aerobic respiration (by measuring oxygen uptake)
- Add set mass of single-celled organism to set volume / conc. of substrate
- Add a buffer to keep pH constant
- Add a set volume / conc. of a chemical that absorbs CO2 eg. sodium hydroxide
- Place in water bath at a set temperature and allow to equilibrate
- Measure distance moved by coloured liquid in a set time
Explain why the respirometer apparatus is left open for 10 minutes. (1)
● Allow apparatus to equilibrate
● Allow for overall pressure change throughout
● Allow respiration rate of organisms to stabilise
Describe a more accurate way to measure volume of gas. (1)
Use a gas syringe
Suggest a suitable control experiment and explain why it is necessary. (2)
- No organisms OR use inert objects OR use dead organisms AND all other conditions / apparatus / equipment the same
● To show that (respiring) organisms are causing liquid to move / taking up oxygen / causing the change in volume / pressure
Describe how a respirometer can be used to measure the rate of anaerobic respiration (by measuring carbon dioxide release)
● Repeat experiment but remove chemical that absorbs CO2
● Make conditions anaerobic, for example:
○ Layer of oil / liquid paraffin above yeast to stop O2 diffusing in
○ Add a chemical that absorbs O2
○ Leave for an hour to allow O2 to be respired and used up
Describe how a respirometer can be used to measure the rate of anaerobic respiration (by measuring carbon dioxide release)
● Repeat experiment but remove chemical that absorbs CO2
● Make conditions anaerobic, for example:
○ Layer of oil / liquid paraffin above yeast to stop O2 diffusing in
○ Add a chemical that absorbs O2
○ Leave for an hour to allow O2 to be respired and used up
What happens with plants/bacteria/animal aerobic respiration and there’s a CO2 absorber?
*CO2 is absorbed in experimental tube
*decrease in pressure
*volume decreases
*volume moves towards the organism
What happens with plants/bacteria/animal aerobic respiration and there’s NO CO2 absorber?
*equilibrium no movement
What happens with bacteria/yeast anaerobic respiration and there’s a CO2 absorber?
*NO O2
*CO2 absorbed
*equillibrium= no movement
What happens with plants/yeast anaerobic respiration and there’s NO CO2 absorber?
*NO oxygen used
*NO CO2 absorbed
*pressure increase
*liquid moves AWAY from organism
I What happens with maggots anaerobic respiration and there’s NO CO2 absorber and there is?
WITH:
*NO CO2 absorbed
*NO O2 uptaken
*equilibrium, no movement
WITHOUT:
*equillibrium, no movement
In maggot anaerobic respiration with CO2 absorber no CO2 in absorbed and NO O2 is uptaken and equillibrium is reached. Why is CO2 not absorbed?
Maggots produces lactate not CO2 so there’s no CO2 to be absorbed
