Respiration Flashcards
Why is respiration important
Produces ATP
For AT
Stages of aerobic respiration and where they occur
Glycolysis - cytoplasm (anaerobic)
Link reaction - mitochondrial matrix
Krebs cycle - mitochondrial matrix
Oxidative phosphorylation - inner
mitochondrial membrane
Stages of anaerobic and where they occur
Glycolysis - cytoplasm
NAD regeneration - cytoplasm
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
Oxidising reduced NAD
So glycolysis can continue
Suggest why anaerobic respiration produces less ATP per molecule of glucose than aerobic respiration
Only glycolysis involved which produces little ATP
What happens after glycolysis if respiration is aerobic?
Pyruvate is actively transported into the mitochondrial matrix
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
Total products per mol: 2 x Acetyl Coenzyme A, 2 X CO2 and 2 X reduced NAD
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
In a series of oxidation-reduction
reactions, the 4C molecule is regenerated and:
2xCO2lost
Coenzymes NAD & FAD reduced
Substrate level phosphorylation
(direct transfer of Pi from intermediate compound to ADP) → ATP produced
Describe the process of oxidative phosphorylation
Reduced NAD/FAD oxidised to release H atoms → split into protons (H+) and electrons (e-)
Electrons transferred down electron transfer chain by redox reactions
Energy released by electrons used in the production of ATP from ADP + Pi - chemiosmotic theory
Energy used by electron carriers to actively pump protons from matrix → intermembrane space
Protons diffuse into matrix down an electrochemical gradient, via ATP synthase, Releasing energy to synthesise ATP from ADP + Pi
Oxygen is final electron acceptor
Give examples of other respiratory substrates
Fatty acids from hydrolysis of lipids → converted to Acetyl Coenzyme A
Amino acids from hydrolysis of proteins → converted to intermediates in Krebs cycle
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 eg. yeast to set volume / conc. of substrate eg. glucose
- 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
Practical question - Explain why the liquid moves.
Oxygen taken in
CO2 given out but absorbed by sodium hydroxide solution
So volume of gas and pressure in container decrease
Fluid in tube moves down pressure gradient towards organism
Explain why the respirometer apparatus is left open for 10 minutes.
Allow apparatus to equilibrate
