3.5.2 Respiration Flashcards
Name the 4 main stages in aerobic respiration and where they occur
Glycolysis - cytoplasm
Link reaction - mitochondrial matrix
Krebs cycle - mitochondrial matrix
Oxidative phosphorylation - via ETC membrane of cristae
Outline the stages of glycolysis
- Glucose is phosphorylated to glucose phosphate by 2x ATP
- Glucose phosphate splits into 2x TP
- 2x TP is oxidised to 2x pyruvate
Net gain of 2x NADH and 2x ATP per glucose
Draw flowchart for glycolysis
Google/notes
How does pyruvate from glycolysis enter the mitochondria
Active transport
What happens during the link reaction
- Oxidation of pyruvate to acetate
per pyruvate molecule: net gain of 1xCO2 (decarboxylation) and 2H used to reduce NAD - Acetate combines with CoA to form acetylcoenzyme A
Summery equation for link reaction
pyruvate + NAD + CoA –>
acetyl CoA + NADH + Co2
What happens in the krebs cycle
series of redox reactions produces
ATP by substrate level phosphorylation
Reduced coenzymes
CO2 from decarboxylation
Outline the stages of the krebs cycle
google/notes
What is the ETC
Series of carrier proteins embedded in the membrane of the cristae of mitochondria
Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
What happens in the ETC
Electrons released from NADH and FADH undergo successive redox reactions
The energy releases is coupled to maintaining the proton gradient or released as heat
Oxygen acts as final electron acceptor
How is a proton conc gradient established during chemiosmosis in aerobic respiration
Some energy released from the ETC is coupled to the active transport of H+ ions (protons) from the mitochondrial matrix into the intermembrane space
How does chemiosmosis produce ATP during aerobic respiration
Protons move down their conc gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase
ATP synthase catalyses ADP + Pi –> ATP
State the role of oxygen in aerobic respiration
Final electron acceptor in the ETC
What is the benefit of an ETC rather than a single reaction
Energy is released gradually
Less energy is released as heat
Name 2 types of molecule that can be used as an alternative respiratory substrates
Amino acids from proteins
Glycerol and fatty acids from lipids
How can lipids act as an alternative respiratory substrate
Lipid –> glycerol and fatty acids
1. Phosphorylation of glycerol –> TP for glycolysis
2. Fatty acid —> acetate
a) acetate enters link reaction
b) H atoms produced for oxidative phosphorylation
How can amino acids act as an alternative respiratory substrate
Deamination produces
1. 3C compounds –> pyruvate for link reaction
2. 4/5C compounds –> intermediates in krebs cycle
Name the stages in respiration that produce ATP by substrate level phosphorylation
Glycolysis (anaerobic)
Krebs cycle (aerobic)
What happens during anaerobic respiration in animals
Only glycolysis continues
NADH + Pyruvate –> NAD + lactate
What happens to the lactate produced in anaerobic respiration
Transported to liver via bloodstream, where it is oxidised to pyruvate
Can enter link reaction in liver cells or be converted to glycogen
What happens during anaerobic respiration in some microorganisms eg yeast and some plant cells
Only glycolysis continues
Pyruvate is decarboxylated to form ethanal
Ethanal is reduced to ethanol using NADH to produced NAD for further glycolysis
Draw a flowchart to show how ethanol is produced during anaerobic respiration
google/notes
What is the advantage of producing ethanol/lactate during anaerobic respiration
Converts NADH back into NAD do glycolysis can continue
What is the disadvantage of producing ethanol during anaerobic respiration
Cells die when ethanol conc is above 12%
Ethanol dissolves cell membranes
What is the disadvantage of producing lactate during anaerobic respiration
Acidic, so decreases pH
Results in muscle fatigue
Compare aerobic and anaerobic respiration
Both involve glycolysis
Both require NAD
Both produce ATP
Contrast aerobic and anaerobic respiration
Aerobic - produces ATP by substrate-level phosphorylation and oxidative phosphorylation
Produces much more ATP
Doesnt produce ethanol or lactate
Anaerobic - substrate level phosphorylation only
Produces fewer ATP
Produces ethanol or lactate
Suggest how a student could investigate the effect of a named variable on the rate of respiration of a single-celled organism
- Use respirometer (pressure changes in boiling tube cause a drop of coloured liquid to move)
- Use a dye as the terminal electron acceptor for the ETC
What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration
Absorbs the CO2 so that there is a net decrease in pressure as O2 is consumed
How could a student calculate the rate of respiration using a respirometer
Volume of O2 produced or Co2 consumed / time X mass of sample
Volume = distance moved by coloured drop x (0.5 x capillary tube diameter)^2 x pie
