Chapter 12 - Respiration Flashcards
What is Glycolysis?
The breakdown of glucose in the cytoplasm and the first step of both anaerobic and aerobic respiration
What is the first step in the breakdown of glucose?
Phosphorylation of glucose - glucose phosphate using ATP
What happens to Glucose Phosphate?
It breaks down into 2 Triose Phosphate molecules
What happens to the TP molecules?
They are broken down into pyruvate molecules and a net gain of ATP molecules as well as reduced NAD
Where does pyruvate go once produced?
It enters the mitochondrial matrix via active transport
Outline the steps of the link reaction
Pyruvate is oxidised to acetate by reducing NAD and losing a CO2 molecule. This acetate molecule then reacts with Coenzyme A to form Acetylcoenzyme A (AcetylCoA)
Outline the major processes of the Krebs Cycle
AcetylCoA bonds with a 4 carbon molecule to form a 6 carbon molecule and drops off CoA, then oxidation and reductions occur resulting in substrate-level phosphorylation (ATP released) and the formation of reduced NAD and FAD as well as the release of CO2, until eventually the original 4 carbon molecule is reformed
What is the function of the Krebs Cycle
Predominantly, it is to form reduced coenzymes FAD and NAD which are essntial for the last stage, oxidative phosphorylation which involves the Electron Transport Chain
How does the electron transport chain work?
The reduced coenzymes donate the electrons from their hydrogen to the first electron transport protein and then they donate their remaining protons to the matrix. As the electron cascades down the chain energy is released which moves the protons through the cristae via active transport. Due to this gradient they are able to move back into the matrix through ATP synthase, and the mechanical movement of the protons essentially “turns” the protein, allowing it to phosphorylate ADP.
Why is oxygen needed in respiration?
It acts as the final electron acceptor, without which the process would end and the final protein would hold onto an electron.
What is different about anaerobic respiration
In anaerobic respiration the reduced NAD formed during glycolysis is used to oxidise the pyruvate into lactate (in mammals) to regenerate the NAD so that glycolysis can continue to release ATP, as the ETC cannot occur without oxygen
Is glucose essential?
No, other respiratory substrates can be broken down such as lipids and amino acids, and then entered into the Krebs Cycle
