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: membrane of cristae
Outline the stages of glycolysis
- Glucose is phosphorylated to glucose phosphate by 2x ATP
- Phosphorylated glucose splits into 2x triose phosphate
- 2x triose phosphate is oxidised to 2x pyruvate
How does pyruvate from glycolysis enter the mitochondria?
Active transport
What happens during the link reaction?
- Oxidation of pyruvate to acetate
2. Acetate combines with coenzyme A to form acetylcoenzyme A
What is the equation for the link reaction?
Pyruvate + NAD + CoA = acetyl CoA + reduced NAD + CO2
What happens in the krebs cycle?
A series of redox reactions produces:
ATP by substrate level phosphorylation
Reduced coenzymes
CO2 from decarboxylation
What is the electron transfer chain?
A 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 electron transport chain?
Electrons released from reduced NAD and FAD undergo successive redox reactions
The energy released is coupled to maintain the proton gradient or released as heat
Oxygen acts as a final electron acceptor
How is a proton concentration gradient established during chemiosmosis in aerobic respiration?
Some energy released from the ETC is coupled to the active transport of H+ from the mitochondrial matrix into the intermembrane space
How does chemiosmosis produce ATP during aerobic respiration?
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 electron transport chain
What is the benefit of an electron transfer chain 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 alternative respiratory substrates
Amino acids from proteins
Glycerol and fatty acids from lipids
How can lipids be used as an alternative respiratory substrate?
- Phosphorylation of glycerol = triose phosphate for glycolysis
- Fatty acid = acetate
Acetate enters the link reaction
H atoms produced for oxidative phosphorylation
How can amino acids act as an alternative respiratory substrate?
- 3C compounds= pyruvate for link reaction
2. 4C/5C compounds= intermediates in the 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
Reduced NAD + pyruvate = oxidised NAD + lactate
What happens to lactate produced in anaerobic respiration?
Transported to the liver via the bloodstream where it is oxidised to pyruvate
Can enter the link reaction in liver cells or be converted to glycogen
What happens during anaerobic respiration in some microorganisms e.g yeast and some plant cells?
Only glycolysis continues
Pyruvate is decarboxylated to form ethanal
Ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis
What is the advantage of producing ethanol/ lactate during anaerobic respiration?
Converts reduced NAD back into NAD so glycolysis can continue
What is the disadvantage of producing ethanol during anaerobic respiration?
Cells die when ethanol concentration 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
Does not produce ethanol or lactate
Anaerobic:
Substrate level phosphorylation only
Produces fewer ATP
Produces ethanol or lactate
