metabolism Flashcards
What is metabolism?
Sum total of all the chemical reactions that occur in a cell
Differentiate between catabolic and anabolic pathways. Which is endergonic and which is exergonic?
Anabolic is a biosynthesis pathway, it uses energy to build up (e.g. monomers to polymers). In is endergonic.
Catabolic is a biodegradation pathway, it releases energy when bonds between molecules are broken (e.g. hydrolysis of ATP to ADP and Pi). It is exergonic.
What is ATP? How is ATP/ADP generated in the cell?
ATP – Adenosine triphosphate, the energy currency of the cell. Made from an adenine, a ribose sugar and three phosphates
ATP is hydrolysed into ADP + Pi. When the triphosphate is broken to diphosphate plus inorganic phosphate there is a release of energy. This cycles back through dehydration.
What is meant by “activation energy”?
the minimum amount of energy required to activate molecules in a reaction
What is an enzyme?
Enzymes are proteins that act as biological catalysts which accelerate chemical reactions
What is a cofactor?
A non-protein molecule that is required to make the enzyme work, but are not part of the substrate
competitive inhibitors
bind to active site of enzyme, competing with the substrate
noncompetitive inhibitors
bind to another part of an enzyme, causing enzyme to change shape and making active site less effective
How does feedback inhibition work?
feedback inhibition is used to ‘turn off’ pathways. Has two binding sites, the active site and an allosteric site.
The product made can bind to the allosteric site, altering the shape of the initial enzyme so that the active site is not available.
If there is no product to bind to the allosteric site, the pathway will continue to make the product. If there is excess product, it binds to the allosteric site, stopping the pathway.
