Respiration Flashcards
4 stages of aerobic respiration
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Features of aerobic respiration
Produces water & carbon dioxide & more ATP.
Features of anaerobic respiration
In animals, it produces lactate. In plants & fungi, it produces ethanol & carbon dioxide. Less ATP.
What are coenzymes?
Molecules required for the functioning of certain enzymes, e.g., by carrying H atoms between molecules.
3 examples of coenzymes
FAD: KREBS CYCLE.
NADP: PHOTOSYNTHESIS.
NAD: works with DEHYDROGENASE ENZYMES that catalyse the removal of H atoms from substrates and transfer them to other molecules involved in OXIDATIVE PHOSPHORYLATION.
How does glycolysis provide indirect evidence for evolution?
It is a universal feature of all living organisms; it is the 1st step of both aerobic and anaerobic respiration.
Where does glycolysis occur?
In the cytoplasm of all living cells.
Summary of glycolysis
Splitting the hexose glucose molecule into 2 triose pyruvate molecules.
Describe the 1st step of glycolysis.
Phosphorylation of glucose to glucose phosphate: glucose is activated/made more reactive by the addition of 2 phosphate molecules.
In the first step of glycolysis, where do the 2 phosphate molecules for the phosphorylation of glucose come from?
They come from the hydrolysis of 2 ATP molecules to ADP. This provides a lower activation energy for the subsequent enzyme-controlled reactions and the energy to activate glucose.
2nd step of glycolysis
Each phosphorylated glucose molecule is split into 2 triose phosphate molecules.
3rd step of glycolysis: oxidation of triose phosphate
Hydrogen is removed from each of the triose phosphate molecules & transferred to NAD (a hydrogen carrier molecule) to form reduced NAD.
4th step of glycolysis: the production of ATP
Enzyme-controlled reactions convert each triose phosphate molecule into 3-carbon pyruvate molecules. 2 molecules of ATP are regenerated from ADP in the process.
What are the overall products of glycolysis?
2 molecules of pyruvate.
2 molecules of reduced NAD.
Net increase of 2 molecules of ATP.
Summary of the link reaction
The triose pyruvate molecules undergo a series of reactions to form 2-carbon acetylcoenzyme A.
Where does the link reaction occur?
The matrix of mitochondria.
Overall word equation for the link reaction
Pyruvate + NAD + CoA —> Acetylcoenzyme A + reduced NAD + CO2
Via series of reactions.
Describe the link reaction in detail.
- The 2 molecules of pyruvate from glycolysis are actively transported into the matrix of the mitochondria.
- The pyruvate is oxidised to acetate. The 3-carbon pyruvate loses a CO2 + 2H.
- The 2H are accepted by NAD to form reduced NAD.
- The 2-carbon acetate combines with coenzyme A to form acetylcoenzyme A.
Where does the Krebs cycle occur?
The matrix of mitochondria.
Summary of the Krebs cycle.
Acetylcoenzyme A is introduced to a cycle of oxidation-reduction reactions that yield some ATP & lots of reduced NAD & FAD.