Respiration Flashcards
What is the equation flr aerobic respiration?
Glucose + oxygen —> carbon dioxide + water
What are the four main stages of aerobic respiration, and where do they take place?
Glycolysis- cytoplasm
Link reaction- mitochondria
Krebs cycle- mitochondria
Oxidative phosphorylation- mitochondria
Describe the role of the mitochondria in respiration
The outer membrane controls the movement of materials
The inner membrane contains electron transport chains for oxydative phosphorylation
The matrix contains enzymes that catalyse the link reaction and krebs cycle
Circular DNaA and 70S ribosomes allow for protein synthesis
Describe the process of glycolysis
The phosphorylation of glucose by ATP converts it to glucose phosphate (ATP comverted back to ADP).
Glucpse phosphate is split into two molecules of tripse phosphate.
Tripse phosphate is oxidised into two molecules of pyruvate. NADaccepts the hydrogen to become rediced NAD
two molecules of ATP are produced per molecule of pyruvate (Pi from triose phosphate and ADP) this is called substrate level phosphorylation
What is the net production for glycolysis?
2X pyruvate
2X NADH
2X ATP
Describe the process of the link reaction
Pyruvate produced in glycolysis is actively transported from the cytoplasm into the matrix.
Pyruvate is oxidised to acetate, the hydrogen released reduced NAD to reeuced NAD.
A molecule of carbon dioxide is released.
Acetate combines with co-enzyme A to produce acetyl coenzyme A
THIS HAPPENS TWICE AS THERE ARE TWO PYRUVATE MOLECULES.
Descrobe the process of the krebs cycle
Acetylcoenzyme A reacts with a 4C compound to make a 6C molecule
This releases coenzyme A (which is reused in the link resction)
The 6C molecule goes through a series of oxidation reactions to produce the 4C molecule again
3 NAD are reduced to 3 reduced NAD, using the hydrogen atoms
1 FAD is reduced to reeuced FAD
2 molecules of carbon dioxide are released
One molecule of ATP is produced by substrate level phosphorylation
The 4C molecule starts the cycle again.
What is thened production of the krebs cycle per molecule of glucose?
2 ATP
6 NADH
2 reduced FAD
4 CO2
Where does oxidative phosphorylation take place?
In the inner mitochondrial membrane of the chloroplast (folds to form cristae)
Describe the process of oxidative phosphorylation
Reduced FAD and NAD release hydrogen, which becomes a proton (H+) and electron.
The elctron passes along the electron transport chain in a series of redox reactions, this releases energy.
This energy is used to pump protons (H+) into the intermembrane space. This creates a conc gradient.
The protons diffuse back into the matrix through ATP synthase. This combones ADP and Pi to make ATP (chemiosmosis)
Pxygen acts as a terminal electron acceptor, combining with the elctrons and protons to create water.
This allows 34 ATP molecules to be made
In oxidative phosphorylation, how many ATP molecules can each NAD and FAD make? Why is there a difference?
NAD releases enough energy for 3, FAD releases enough energy for 2 because the reduced FAD binds later than NADH in the electron transport chain.
What are two alternative respiratory substrates?
Lipids and proteins
Explain how lipids can be used for respiration
They are hydrolysed into glycerol and fatty acids.
Glycerol is converted to triose phosphate and then enters glycolysis
Fatty acids can be converted into many hydrogen atoms (for oxidative phosphorylation) and 2- carbon molecules, which can be converted into acetyl coenzyme A for the krebs cycle
Explain how proteins can be used for respiration
Hydrolysed to their constituent amino acids
Amino groups are removed, leaving carbon molecules
Enter respiratory pathways depending on how many carbons they contain
Why can only glycolysis occur in anaerobic conditions?
Glycolyis, it is the only stage that does not require oxygen
