ENZYMES Flashcards
Enzymes have great specificity, explain
Globular proteins have a very specific shape as a result of their primary secondary, tertiary and quaternary structure. This means that each enzyme will only catalyse a specific reaction
what do we call reactions that build up new chemicals
Anabolic
what do we call reactions that break down substances
catabolic
what do we call a combination of catabolic and anabolic reactions
Metabolic
examples of extracellular enzymes
digestive enzymes
lysome-tears
state what is meant by an enzyme
proteins that have very specific shape as a result of their primary, secondary tertiary and quaternary structures.
identify enzymes that catalyse reactions outside of cells
Extracellular enzymes
examples of intracellular enzymes
DNA polymerase
DNA ligase
state what is meant by a catalyst
a substance that speeds up reactions without changing the substance being produced or being changed itself
define metabolic chain (Metabolic pathway)
a series of linked reactions in the metabolism of a cell
identify enzymes that catalyse reactions within the cell
Intracellular enzymes
For reactions to take place , reacting molecules must have enough energy to break the chemical bonds that hold them together… what is this energy called?
Activation energy
Lock and key hypothesis can be replaced by what theory? outline it
Induced fit hypothesis-the active site still has a distinctive shape but it is flexible. Once the substrate enters the active site, its shape modifies around it to form an active complex.
the enzyme reverts to its inactive and relaxed form until another substrate molecule binds
define what is meant by molecular activity/ turnover number
the number of substrate molecules transformed per minute by a single enzyme molecule
describe the effect of temperature on enzyme efficacy
Kinetic energy increases, substrate particles move around faster increasing the chances of particles colliding into the active site.
the rate of reaction doubles for every 10 C increase in temp
Low temperatures inactivate the enzyme
Temperatures above the optimum temp may denature the enzyme
describe the effect of pH on enzyme efficacy
Changes shape of protein molecules as the charges on the amino acid side chains are affected by hydrogen of hydroxide ions.
describe the effect of concentration of enzyme efficacy
As the concentration of a substrate increases if the amount of enzyme stays constant the rate of reaction will increase.
at some point all the enzyme active sites will be working at full capacity , therefore rate of reaction will plateau.
state the role of buffers
maintain a constant pH
What are enzyme inhibitors
substances that slow down enzymes or stop them from working
what is reversible inhibition
inhibition of the action of an enzyme by an inhibitor that does not permanently affect the functioning of the enzyme and can be removed from the enzyme. Often used to control the reaction rates within a cell
What is irreversible inhibition
the inhibition of the action of an enzyme that is permanent and cannot be undone. It is never used within cells to control the rate of reaction.
what is competitive inhibition
inhibition where the inhibitor molecule is similar in shape to the substrate molecule and competes with it for the active site of the enzyme (affected by both substrate concentration and inhibitor)
what is non competitive inhibition
inhibition in which the inhibitor does not compete for the active site but forms a complex with the enzyme or enzyme substrate complex and changes the shape of the active site so it can no longer catalyse the reaction (affected by only the concentration of inhibitor)
outline end product inhibition
control system in many metabolic pathways in which an enzyme at the beginning of the pathway is inhibited by one of the end products of the reaction.
what do products bind to in end product inhibition
allosteric site of enzyme
