Cellular respiration Flashcards
Anaerobic
In the absence of oxygen. Anaerobic respiration breaks down organic molecules
Aerobic
In the presence of oxygen. Aerobic respiration breaks down organic molecules and uses oxygen as the final electron acceptor in the ETC
Fermentation
Partial degradation of sugars in the absence of oxygen. when glycolysis occurs in the absence of oxygen and there are no further respiration steps, fermentation is used to regenerate NAD+. If this didn’t happen, glycolysis cannot occur because there would be no NAD+ molecules to accept the electrons (NAD+ could not be reduced to NADH).
Phosphorylation
Addition of a phosphate group to a compound.
oxidative phosphorylation
Oxidative phosphorylation occurs in the ETC, ATP is made through the use of electron carriers, this is how most ATP is generated in eukaryote
substate level phosphorylation
Substrate level phosphorylation occurs in glycolysis and TCA, more direct way of making ATP but uses more energy to do so (less net gain) because coupled to high energy source intermediary (substrate)
ATP
Adenosine triphosphate, the main energy currency of the cell. Energy is held in phosphate bonds, if you break ATP to ADP you release that energy
What is meant by a “redox” reaction?
Reduction-oxidation - if a molecule is reduced it will have a reduced charge (gains electrons), oxidised will lose electrons
What are the three steps of cellular respiration that will occur in an aerobic eukaryotic cell?
Glycolysis - in the cytoplasm, this is substrate level phosphorylation meaning it uses enzymes
The citric acid cycle – in the mitochondrial matrix, substrate level
Electron transport chain – inter-membrane of the mitochondria, oxidative phosphorylation (creates a proton gradient that can be used to make ATP using ATP synthase enzyme)
What is glycolysis and where does it occur in all organisms?
The initial breakdown of energy molecule during cellular respiration. Occurs in the cytoplasm.
What are the two common products of pyruvate breakdown during fermentation?
Lactic acid and ethanol
What does pyruvate convert to before entering the citric acid cycle? Where does this happen in the cell?
Pyruvate is oxidised to Acetyl CoA. 3C molecule converted to 2C molecule, as a result the lost C is CO2 and NAD+ is reduced to NADH and H+. This happens for each pyruvate, therefore for one glucose at the start of glycolysis this produces 2x CO2, 2 x NADH and 2 x H+. happens in the mitochondrial matrix
Where does the citric acid (TCA) cycle occur in eukaryotes?
Matrix of the mitochondria
What is the role of the ETC?
Generate a H+ gradient that can be used to drive ATP synthesis
What is chemiosmosis and why is it important for cellular respiration?
This is how ATP is generated from the hydrogen ion gradient set up by the ETC. It uses the unequal amount of H+ on one side to drive ATP synthase, H+ enter the ATP synthase molecule and it uses this proton motive force to turn and generate ATP, pushing the H+ ion back into the matrix. Without the ETC there would be no gradient to drive ATP synthase.
