CH12 Respiration Flashcards
4 main stages in aerobic respiration and their locations
Glycolysis - Cytoplasm
Link reaction - Mitochondrial matrix
Krebs cycle - Mitochondrial matrix
Oxidative phosphorylation - ETC - membrane of cristae
Stages of glycolysis
Glucose phosphorylated to glucose phosphate by 2ATP
Glucose phosphate splits into 2 triose phosphate
2 TP is oxidised to 2 pyruvate
Net gain of 2 reduced NAD and 2 ATP per glucose
How does pyruvate from glycolysis enter mitochondria
Active transport
What happens in link reaction
- Oxidation of pyruvate to acetate
per molecule of pyruvate - net gain of 1 CO2 and 2H atoms (used to reduce NAD) - Acetate combines with coenzyme A to form acetylcoenzyme A
What happens in Krebs cycle
Series of redox reactions produces:
ATP by substrate-level phosphorylation
Reduced coenzymes
CO2 from decarboxylation
What is the electron transfer chain (ETC)
Series of carrier proteins embedded in membrane of the cristae of mitochondria
Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
What happens in the ETC
Electrons released from reduced NAD and FAD undergo successive redox reactions
The energy released is coupled to maintaining a proton gradient or released as heat
Oxygen is the final electron acceptor
How is a proton concentration established
Some energy released from the ETC is coupled with the active transport of H+ ions from the mitochondrial matrix into the intermembrane space
How does chemiosmosis produce ATP
H+ ions move down their concentration gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase
State the role of oxygen in aerobic respiration
Final electron acceptor in ETC
Produces water as a byproduct
Benefit of ETC rather than single reaction
Energy released gradually
Less energy released as heat
2 types of molecules that can be used as alternative respiratory substrates
Proteins - AA
Lipids - glycerol and fatty acids
How can lipids act as alternative respiratory substrate
Lipid –> glycerol + 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 AA act as an alternative respiratory substrate
Deamination produces:
- 3C compounds - pyruvate for link reaction
- 4C / 5C compounds - intermediates for Krebs cycle
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
reduced NAD + pyruvate –> oxidised NAD (for further glycolysis) + lactate
What happens to 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
Only glycolysis continues
Pyruvate is decarboxylated to form ethanal
Ethanal reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis
Advantage of producing ethanol / lactate during anaerobic respiration
Converts reduced NAD back into NAD so glycolysis can continue
Disadvantage of producing ethanol
Cells die when ethanol conc is above 12%
Ethanol dissolves cell membranes
Disadvantage of producing lactate
Acidic, 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 but anaerobic only produces ATP by substrate-level phosphorylation
Aerobic produces more ATP than anaerobic
Aerobic does not produce ethanol or lactate but anaerobic does
How to investigate effect of variable on rate of respiration of single-celled organism
Use respirometer
Use a dye as the terminal electron acceptor for the ETC
Purpose of sodium hydroxide solution in respirometer
Absorbs CO2 so there is a net decrease in pressure as O2 is consumed
