chapter 3 - enzymes Flashcards
what are enzymes?
organic catalysts that lower the activation energy of reactions.
what do enzymes do
enzyme’s active site binds to substrate that is
complementary in shape - forms enzyme substrate complex.
substrate undergoes a chemical reaction and forms product(s).
what does the active undergo upon binding
conformational change to accommodate the substrate
what are the ten features of enzymes
- reusable
- specific
- reversible
- speed up, not create
- have an active site
- are proteins
- subset of catalysts
- act on biochemical pathways
- end in ‘ase’
- above the arrow (explain)
what is activation energy
The minimum amount of energy required to energise atoms/molecules to a state where they can undergo a chemical transformation.
what is an anabolic reaction
when two or more smaller molecules combine to form a larger one.
Requires an input of energy.
what is a catabolic reaction
a larger molecule turning into two or more smaller molecules.
Energy is released
what are the 6 factors affecting enzymes
temperature, pH, concentration, competitive + non-competitive inhibition, coenzymes
what happens to enzyme activity when it’s too cold?
- activity decreases
- molecules move slower + collide less frequently.
- experience little to no activity and can freeze (reversible)
what happens to enzyme activity at optimal temp?
- molecules have greater kinetic energy
- collide more frequently
- more enzyme-substrate complexes form.
what happens to enzyme activity when it’s too hot?
- denaturation (hydrogen bonds to break)
- conformational change in the active site, causing the substrate to no longer fit. (irreversible)
what happens to enzyme activity when the pH is too acidic or basic?
enzymes denature at non-optimum pHs, depending on where they are located
what does increasing SUBSTRATE concentration do?
- increases reaction rate
- increases the number of collisions
- eventually all active sites will become saturated (full), and rate of reaction will not increase (plateau).
what does increasing ENZYME concentration do?
- more enzyme molecules means more active sites available for substrates to bind to, resulting in faster rate of reaction.
- excess in enzymes causes reaction rate to plateau. (not enough substrate)
what is competitive inhibition?
- when an inhibitor molecule complementary in shape binds to an enzyme’s active site, directly occupying and blocking the active site.
- substrate can no longer bind with the enzyme and no reaction will occur
what is non-competitive inhibition?
- when an inhibitor binds to an enzyme at a site other than the active site (an allosteric site).
- causes a conformational change in the active site’s structure
- prevents the substrate from binding to it, preventing the reaction from occurring.
what are coenzymes?
- a subset of cofactors that assist enzymes in catalysing reactions.
what is ATP?
Adenosine triphosphate is the main coenzyme of the cell.
what does ATP do?
- undergoes coenzyme cycling
- ATP (loaded) loses a phosphate group and becomes ADP (unloaded)
- ADP has phosphate group re-added (ATP again)
what do coenzymes do?
- bind to active site and donates energy or molecules.
- is recycled by accepting more energy, to assist in more reactions.
