L14- Introduction to metabolism Flashcards
What does a multistep enzyme pathway do?
Releases energy in smaller amounts so that eaxch small packet of energy can be used by the cell
What do metabolic pathways’ flow of materials depend on?
- Supply of substrates
- Removal of products
- . Pathway enzymes activities (rates of rxns)
What is feed-forward activation?
Metabolite early in the pathway activates an enzyme further down the pathway
How are enzymes rapidly and reversibly altered?
By covalent modification of enzyme-
Protein kinases phosphorylate enzyymes
Protein phosphatases remove phosphate groups
What is ∆G? When is a reaction favoured?
Free-energy change. A measure of the chemical energy available from a reaction.
-∆G = favoured reaction
Whats the equation of ∆G?
∆G= ∆H - T∆S
(you want a negative enthalpy chnage and a positive entropy change which will make a negative gibbs energy change)
What 3 types of compounds does catabolism produce for energy utilization?
- Nucleoside triphosphates (eg ATP)
- Acetyl Coenzyme A (acetyl coA)
- Reduced coenzymes (NADH, NADPH, FADH2, QH2)
How is energy from oxidation of metabolic fuels recovered?
In the form of ATP
Which bonds in ATP, GTP etc release los of energy when hydrolysed?
Phosphoanhydride bonds
What kind of compound is acetyl coA and why is it useful?
A thioester. Thioesters have high free energies of hydrolysis
What is oxidized in th catabolic pathways?
Amino acids, monosaccharides and lipids
What happens to most of the NADH formed in cells?
It’s oxidized in the respiratory electron transport chain
What happens to the enrgy generated by NADH oxidation?
It’s used to produce ATP from ADP and phosphate
What’s rh free energy change during oxidation of NADH by oxygen?
-220 KJ/mol
