Respiration Flashcards
Name the 4 stages of Aerobic respiration
Glycolysis: Cytoplasm
Link reaction: Mitochondrial Matrix
Krebs cycle: Mitochondrial Matrix
Oxidative phosphorylation via electron transfer chain: Membrane of Cristae
Outline the stages of glycolysis
3
- Glucose is phosphorylated to glucose phosphate by 2x ATP
- Glucose phosphate splits into 2x triose phosphate (TP)
- 2x TP is oxidised to 2x Pyruvate
Net gain of 2x reduced NAD & 2x ATP per glucose.
Draw a flowchart to represent what happens during glycolysis
Compare to diagram
How does pyruvate from glycolysis enter the mitochondria?
Via active transport
What happens during the link reaction?
- Oxidation of pyuravate to acetate.
Per pyruvate molecule: net gain of 1xCO₂ (decarboxylation) & 2H atoms (used to reduce
1x NAD)
- Acetate combines with coenzyme A (CoA) to form acetyl coenzyme A.
What are the two types of cellular respiration
Aerobic respiration - Requires oxygen and produces carbon dioxide, water and much ATP
Anaerobic respiration - takes place in the absence of oxygen and produces lactate (in animals) or ethanol and carbon dioxide (in plants and fungi) only little ATP
Glycolysis
The splitting of the 6-carbon glucose molecule into two 3-carbon pyruvate molecules
Link reaction
The 3-carbon pyruvate molecules enter into series of reactions which lead to the formation of acetylecoenzyme A, a 2-carbon molecule.
Give a summary equation for the link reaction.
pyruvate + NAD + CoA
→
acetyl CoA + reduced NAD + Co₂
Krebs cycle
The introduction of acetyl coenzyme A into a cycle of oxidation-reduction that yield some ATP and a large quantity of reduced NAD and FAD.
What happens in the Krebs cycle?
Series of redox reactions produces:
- ATP by substrate-level phosphorylation
- Reduced coenzymes.
- Co₂ from decarboxylation
Oxidative phosphorylation
The use of the electrons associated with reduced NAD and FAD, released from the Krebs cycle to synthesise ATP with water produced as by-product.
What is the electron transfer chain (ETC)?
Series of carrier proteins embedded in membrane of the cristae of mitochondria.
Produces ATP through oxidate phophorylation via chemiosmosis during aerobic respiration.
What happens in the electron transfer chain (ETC)?
Electron released from reduced NAD & FAD undergo successive redox reactions>
The energy released is coupled to maintaining proton gradient or released as heat.
Oxygen acts as final electron acceptor.
How is a proton concentration gradient establushed during chemiosmosis in aerobic respiration>
Some energy released from the ETC is coupled to the active transport of H⁺ ions (protons) fron the mitochondrial matrix into the intermembrane space.
How does chemiosmosis produce ATP during aerobic respiration>
H⁺ ions (protons) move down their concentration gradient from intermembrane space into 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 electron transfer chain.
Prodcues water as a byproduct
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 respiratiory substrates.
- (Amino acids from) proteins
- (Glycerol and fatty acids from) lipids
How can lipids act as an alternative respiratory substrate>
Lipid → glycerol + fatty acids
- Phosphorylation of glycerol → TP for glycolysis.
- 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:
- 3C Compounds → pyruvate for link reaction,
- 4C/5C compounds → intermediates in Kerbs cycle.
Name the stages in respiration that produces ATP by substrate-level phosphorylation.
Glycolysis (anaerobic) Krebs cycle (aerobic)
What happens during anaeobic respiration in animals?
Only glycolysis continues
Reduced NAD + pyrvuate
Oxidised NAD (for further glycolysis) + lactate
Pyruvate acts as hydrogen acceptor
↓ reduced Nad
↪ Oxidised NAD
lactate
Refer to PM
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 respirtation in some microorganis e.g yeast and some plants cells?
Only glycolysis continues,
Pyruvate is decarboxylated to form ethanal.
Ethanal is reduced to ethanol using reduced NAD is to produce oxidised NAD for further glycolysis.
Draw a flowchart to show how ethanol is prduced during anaerobic respiration.
Pyruvate
decarboxylation
↓ ↪ Co₂
ethanal
Reduction ↓ reduced NAD
↪ oxidised NAD
ethanol
Refer to PM
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 anerobic 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
Constrast 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
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 to measure the rate of aerobic respiration?
Absorb CO₂ so that there is a net decrease in pressure as O₂ is not 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
π
