Respiration Flashcards
What is the purpose of respiration?
To produce ATP
What is the first stage of respiration?
Glycolysis
Is glycolysis aerobic or anaerobic?
Anaerobic, does not require respiration
Where does glycolysis take place?
In the cytoplasm of the cell
What is glucose converted to and how?
hexose 1,6 bisphosphate through phosphorylation by ATP
What is hexose 1,6 bisphosphate broken down to?
2 three-carbon molecules- triose phosphate
What is the final product of glycolysis and how is it produced?
Pyruvate, made by the dephosphorylation of triose phosphate.
What are the net products of glycolysis?
2x ATP, 2x NADH, 2x pyruvate
What is the stage that occurs after glycolysis in aerobic conditions?
The link reaction
Where does the link reaction occur?
The mitochondrial matrix
How does pyruvate get to the link reaction?
It actively transports from the cytoplasm into the matrix of the mitochondria
What is pyruvate converted to in the link reaction and how?
Acetate through decarboxylation and oxidation
What is the final product of the link reaction and how is it produced?
Acetylcoenzyme A, by binding acetate and coenzyme A
What stage occurs after the link reaction?
The Krebs Cycle
How many carbons does AcetylcoA contain?
2
How is a 6 carbon molecule produced from AcetylCoA in the Krebs Cycle?
Oxaloacetate joins with AcetylCoA to produce citrate
How does citrate produce oxaloacetate
- Decarboxylation occurs twice
- 2 NAD molecules are reduced at the same time
- ADP is phosphorylated
- An FAD molecule is reduced
- another NAD molecule is reduced
- Oxaloacetate is produced
What are the net products of the Krebs cycle?
3x NADH, 1x FADH₂, 1x ATP, 2x CO₂
Where are NADH and FADH₂ transported to after the Krebs Cycle?
The intermembrane space of the mitochondria
Where does the electron transport chain take place?
The intermembrane space of the mitochondria
What are NADH and FADH₂?
Co-enzymes
What happens to NADH and FADH₂ in the electron transport chain?
The are oxidised to release H+ atoms
What happens to electrons as they move down the electron transport chain?
They release energy
What is the last carrier in the electron transport chain and what is it reduced to?
Oxygen is reduced to water
What happens to hydrogen atoms in chemiosmosis?
They are actively transported into the matrix, from which they enter the proton port of the ATP synthase molecules embedded into the membrane
What is the name of the proton gradient established at the membrane?
electro-chemical gradient
What happens to ATP synthase when H+ diffuses through?
It begins to spin so it gains kinetic energy which allows ADP to be phosphorylated to ATP
Describe anaerobic respiration in animals
- glycolysis still occurs
- NADH is recycled and oxidised to NAD
- Pyruvate acts as a H acceptor so it is converted to Lactate in muscle cells
- Lactate is taken to the liver where it is reconverted to pyruvate to continue to the link reaction there
Describe anaerobic respiration in yeast
- NAD is recycled
- Pyruvate undergoes decarboxylation and reduction to produce ethanol
- If the ethanol conc. exceeds 12% all cells will die
- Because the ethanol dissolves in cell membranes which causes them to swell and burst
What is a respiratory substrate?
An organic substance that can be used for respiration
Describe carbohydrates as respiratory substrates
Glucose is the main respiratory substrate
The brain and blood cells can only use glucose
Describe proteins as respiratory substrates
Some of the molecule can be changed to glycogen
Some is converted to pyruvate and continue to Krebs cycle
Slightly higher energy yield than carbohydrates
Describe lipids as respiratory substrates?
Glycerol can be converted to glucose
Fatty acids (hydrocarbons) can produce ATP through chemiosmosis
Can bind with CoA and enter Krebs cycle
Highest energy yield
Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.
- NAD is regenerated
- Which can be reduced again in glycolysis
What is the effect of lactate in muscle cells?
Causes cramps due to toxicity
What is the main role of oxygen in respiration?
Acts as an electron acceptor as it is reduced to form water (addition of electrons)
