Respiration Flashcards
Define respiration
The process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.
Define metabolism
The sum total of all chemical reactions that occur in the body
What is anaerobic vs aerobic respiration?
Anaerobic is respiration that does NOT require O2
Aerobic = respiration that requires O2
What are the 4 main steps of cellular respiration?
Glycolysis
Link Reaction
Krebs/ Citric acid cycle
Oxidative phosphorylation (aka electron transport chain)
What are the 4 main stages of Glycolysis?
1) phosphorylation of glucose
2) Lysis (splitting) of phosphorylated glucose
3) Oxidation of triose phosphate
4) ATP formation
What are the products of glycolysis?
2x Pyruvate (3C)
4x ATP (but only 2 are gained)
2x NADH
2x H+
Where does glycolysis happen?
In the cytosol of the cell (aka cytoplasm)
Where does the link reaction happen?
In the matrix of the mitochondria
What are the main stages of the link reaction?
1) Pyruvate is oxidised, so NAD is reduced
2) Pyruvate is decarboxylated
What are the products from the link reaction?
2x Acetyl CoA (2C)
2x Co2
2x NADH
2x H+
Where does the Krebs cycle happen?
In the matrix of the mitochondria
What is the main process of the Krebs cycle?
1) Acetyl CoA binds with a 4C sugar to make citrate (6C) - NAD oxidises this (and is reduced to NADH)
2) Citrate is decarboxylated (becomes 5C)
3) The 5C sugar is oxidised by more NAD and FAD (they become reduced)
4) The 5C sugar is decarboxylated again (becomes 4C) - 1 ATP molecule is produced
5) The 4C sugar is added to the next CoA to continue the cycle
What are the products of the Kerbs cycle per 2 pyruvate molecules?
4x CO2
2x ATP
2x FADH2
6x NADH + H+
What products starts off in glycolysis?
Glucose - 6C molecule
What product starts off the link reaction?
2x Pyruvate (3C molecules)
What product starts of the Krebs cycle?
2x Acetyl CoA (2C molecules)
What products are used to start off the electron transport chain?
Hydrogen protons
Where does oxidative phosphorylation happen?
Inner mitochondrial membrane (cristae)
What is oxidative phosphorylation?
The formation of ATP by adding a phosphate group to ADP, in the presence of oxygen
What does the electron transport chain do?
Releases energy stored in the hydrogen carriers to synthesise ATP through oxidative phosphorylation
What are the basic steps of oxidative phosphorylation?
1) Proton pumps create electrochemical gradient (proton motive force)
2) ATP synthase uses the subsequent diffusion of protons (chemiosmosis) to synthesis ATP
3) Oxygen is reduced, accepting electrons and protons – forms water
How is the proton motive force generated?
1) NADH and FADH2 are oxidsed, releasing high energy electrons and protons
2) The electrons pass through the ETC, losing energy to the chain to pump protons from the matrix
3) Protons collected in the intermembrane space create electrochemical gradients - the proton motive force
How does chemiosmosis synthesis ATP?
1) H+ protons are diffused back to the matrix by proton motive force
2) The diffusion is called chemiosmosis
3) The protons move through ATP synthase, triggering enzyme rotation and phosphorylation reaction - causes synthesis of ATP
What is the role of oxygen in oxidative phosphorylation?
It acts as an electron acceptor
It removes de-energized electrons (becomes reduced) - forming water to maintain the hydrogen gradient
What is chemiosmosis?
The flow of hydrogen ions (protons) across a membrane
How many ATP molecules are produced from one glucose molecule in aerobic respiration?
38
