mod10 enzymes

what is an enzyme:

proteins that act as catalysts

how are enzymes similar to inorganic catalysts:

increases reaction rate, lowers activation energy

not consumed in the reaction

explain absolute specificity:

enzyme will catalyse one reaction of only one substance

explain relative specificity:

enzyme will catalyse the reactions of any structurally related substance

explain stereochemical specificity:

enzyme will only catalyse reactions of 1 3D shape

how does enzyme regulation occur:

cells control amount and type of chemical reactions occurring by controlling presence of enzymes

describe common enzyme nomenclature:

ends in -ase

how is the shape of an enzyme determined:

primary, secondary, tertiary and quaternary structure of polypeptides

an enzymes activity is related to:

its 3D shape at the active site

how is an enzyme-substrate complex formed:

enzyme active sites have very specific shape and only a substrate of thee exact shape can fit and react forming lock and key model

how does enzyme-substrate complex react:

functional groups on enzyme react with substrate to form products

explain the active site in a lock and key model:

rigid active site

active site is exactly right to match incoming substrate

explain induced fit model:

enzyme has flexible structure that can adapt the shape of active site to match substrate

define cofactor:

small non-protein molecule or ion that the enzyme needs to function

deine coenzyme:

an organic cofactor

define apoenzyme:

what is left when cofactors are removed from the enzyme

factors that affect enzyme activity:

enzyme concentration

substrate concentration

pH

temperature

if enzyme activity is high _____:

reaction rate is increased

if enzyme activity is low, ______:

reaction rate is the same without an enzyme

how does enzyme conc affect enzyme activity:

increased enzyme concentration increases reaction rate

how does substrate conc affect enzyme activity:

rate will increase until all sites are occupied then rate remains constant

how does pH affect enzyme activity:

most enzymes work at physiological pH (7), some adapt to work in extreme conditions

alters chemical bonds that holds enzymes 3D shape and active site

how does temperature affect enzyme activity:

work most effectively at physiological temperature (37), higher becomes denatured

how do inhibitors affect enzyme activity:

decrease rate of reaction

posions or medicines

how does irreversible inhibition occur:

inhibitor binds to a specific functional group in the enzyme, preventing the enzyme from working

example of irrevirsble inhibitors:

cyanide ions

heavy metals (Pb²⁺, Hg²⁺)

explain reversible inhibition:

act as regulatory process, prevents enzyme from reacting too often

explain competitive inhibition:

bids to active site, competing with substrate

must have similar molecular structure to substrate

explain uncompetitive inhibition:

binds to enzyme other than the active site

causes 3D shape of the enzyme to change, and active site shapes changes

enzyme no longer has shape to bind to substrate