4) Enzymes Flashcards
Describe enzymes
Globular proteins
Describe the lock and key model
Substrate fits into an enymes active site, this is complementary to eachother . THis creates an ezyme-substrate complex
What is the induced fit of an enzyme
Enzymes are specific to a particular substrate . The actice site will change shapethe right wat to fit the substrate even better
How does temperature affect enzyme activity
Temp inc , rate inc
More kinetic energy , move faster, more likely to collide so energy of reaction increases.
Molecules vibrate more , break some bonds , active site changes shape , enzyme nolonger fit to substrate
Low temp- reactions work slowly
High temp- enzymes denature
How does pH affect enzyme activity
Have an optimum value ,
Hydrogen and hydroxide ions can alter ionic vonds and hydrogen bonds.
Cause active site to denature
How does enzyme concentration affect enzyme activity
More enzymes molecules , increase enzyme-substrate complex .
Substrate is limited , point where there is no more active sites , no further affect
How does substrate concentration affect enzyme activity
Higher concentration of substrate , faster reaction , collision more likely to more active sites will be used.Until saturation , all active sites are full to adding more makes no difference.
Enzyme concentration becomes the limiting factor.
What are cofactors
Non-protein substances that bound to enzymes .
Inorganic or ions .
eg , chloride ions for amylase
What are coenzymes
organic molecules , carriers moving chemical groups .
for eg , vitamins.
what are prosthetic groups
cofactors that are tightly bound to enzymes.
eg zinc for carbonic anhydrase.
Describe competitive inhibition
Similar shape to substrate
Compete with substrate for same active site.
High conc on inhibitor, take up active sites quicker.
what is non-competitive inhibition
Bind away from the active site - allosteric site.
WHen binds , cause active site to change shape permanently
Vmax is much lower.
Describe end product inhibition
Product of first reaction takes part in the second reaction etc etc
Final product in a metabolic pathway inhibits an enzyme that acts earlier on in the pathway.
-Way of controlling amount of end-product.
Reversible
How does enzyme inhibition help to protect cells
Inactive precursors to prevent cell damage.
Part of the molecule inhibits its action as an enzyme ,this part is then removed to allow enzyme to be active.
