B12 Respiration Flashcards
Name the 4 main stages in Aerobic respiration and where they occur.
Glycolysis - cytoplasm
Link reaction - matrix of mitochondria
Krebs cycle - Matrix of mitochondria
Oxidative Phosphorylation (via electron transfer chain) -membrane of Cristae
Outline the stages of glycolysis.
. Glucose is phosphorylated to phosphorylated glucose by 2 ATP
. phosphorylated glucose splits to 2x triose phosphate
. 2x Triose phosphate is oxidised to 2x pyruvate
Net gain of 2x NADH and 2x ATP per glucose
How does pyruvate from glycolysis enter the mitochondria?
Via Active Transport
What happens during the link reaction?
. 2x Pyruvate (3C) is oxidised to 2x Acetate (2C), with the loss of 2x CO2 and 2H+ are lost and reduce NAD to form reduced NAD (decarboxylation)
. Acetate (2C) combines with coenzyme A (CoA) to form Acetyl coenzyme A
Summary equation of link reaction.
Pyruvate + NAD + CoA -> Acetyl CoA + reduced NAD + CO2
What happens in the Krebs Cycle?
Series of redox reactions produce:
. ATP by substrate-level phosphorylation
. Reduced coenzymes
. CO2 from decaroboxylation
What is the ETC?
Series of carrier proteins embedded in in membrane of the Cristae of the mitochondria.
Produces ATP through oxidative phosphorylation via chemiosmosis during Aerobic respiration.
What happens in the ETC?
Electrons released from reduced NAD & FAD undergo successive redox reactions.
The energy released is couples to maintaining proton gradient or released as heat.
Oxygen acts as final electron acceptor.
How is a proton concentration gradient established during chemi-osmosis in aerobic respiration?
Some energy released from ETC is coupled to the active transport of H+ from the mitochondrial matrix into the inter-membrane space.
How does chemiosmosis produce ATP during aerobic respiration?
H+ move down their concentration gradient from the inter-membrane 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 electron transfer chain.
(Produces water as a bi-product)
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 molecules 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 + fatty acids
- phosphorylation of glycerol -> TP for glycolysis
- fatty acids -> acetate
a) acetate enters link reaction
b) H atoms produced for oxidative phosphorylation
How can amino acids act as an alternative respiratory substrate?
Deaminating produces:
3C compounds -> pyruvate for link reaction
4C/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 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 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
Similarities of aerobic and anaerobic respiration.
Both:
Involve glycolysis
Require NAD
Produce ATP
Differences of 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 names 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 dye as the terminal electron acceptor for the ETC.
What is the purpose of NaOH in a respirometer set up to measure the rate of aerobic respiration?
Absorbs CO2 so that there’s 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 π
What are the 4 stages of aerobic respiration and where do they occur
Glycolysis (cytoplasm)
Link reaction (mitochondrial matrix)
Krebs Cycle (mitochondrial matrix)
Oxidative phosphorylation (mitochondrial inner membrane-cristae)
What does respiration produce
ATP
What stage occurs in both anaerobic and aerobic respiration
Glycolysis is the first stage of anaerobic and aerobic respiration.
It occurs in the cytoplasm and is an anaerobic process.
What are the 3 steps glycolysis involves
- Phosphorylating glucose to glucose phosphate, using ATP
- The production of triose phosphate
- Oxidation of triose phosphate to produce pyruvate with a net gain of ATP and reduced NAD.
What’s are the products of glycolysis
2 pyruvate
Net gain of 2 ATP
2 NADH
What happens to pyruvate and NADH after they are procured in glycolysis
Pyruvate and NADH are actively transported from the cytoplasm into the mitochondrial matrix
What happens in the link reaction
The pyruvate made in glycolysis is oxidised to acetate.
NAD picks up the hydrogen and becomes reduced NAD
Acetate the combines with coenzyme A in to produce acetylcoenzyme A
What does the link reaction Produce if it occurs twice for every glucose molecule
2 x Acetyl CoA
2 CO2 released
2 reduced NAD
What happens in the Krebs cycle
Acetyl-CoA reacts with a 4 carbon molecule, releasing coenzyme A and producing a 6 carbon molecule that enters the Krebs cycle
In a series of Redox reactions, the Krebs cycle generates reduced coenzymes and ATP by substrate-level phosphorylation, and carbon dioxide is lost
What are the products per cycle of the Krebs suckle
3 x reduced NAD I x reduced FAD
1 x ATP
2 x CO2
What does the Krebs cycle produce per glucose molecule
6 x reduced NAD
2 x reduced FAD
2 × АТР
4 x CO2
What stage is ATP produced the most
Oxidative phosphorylation
What does oxidative phosphorylation involve
The electron transfer chain
Movement of protons across the inner mitochondrial
membranes
Catalysed by ATP synthase
When does anaerobic respiration occur
In the absence of oxygen
Where does anaerobic respiration occur
In the cytoplasm only
What happens in anaerobic respiration
The pyruvate produced in glycolysis is reduced to form ethanol and carbon dioxide (in plants and microbes) or lactate (in animals) by gaining the hydrogen from reduced NAD.
This oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced.
Anaerobic respiration in animals
The pyruvate produced in glycolysis is reduced to form lactate in animals by gaining the hydrogen from reduced NAD.
This oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced.
Anaerobic respiration in plants
The pyruvate produced in glycolysis is reduced to form ethanol and carbon dioxide in plants and microbes gaining the hydrogen from reduced NAD.
This oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced.
Efficiency of anaerobic respiration
One reduced NAD can result in a yield of 3 ATP molecules, whereas I reduced FAD can result in a yield of 2 ATP molecules.
Therefore, the total yield of ATP from one glucose molecule in aerobic respiration should be 38 molecules of ATP. Aerobic respiration is approximately 32% efficient. This is due to some protons leaking across the mitochondrial membrane during oxidative phosphorylation, ATP being used to actively transport pyruvate and NADH into the matrix and because some energy is lost as heat.
Anaerobic respiration is even less efficient, because only 2 ATP molecules and produced from one glucose molecule.
