Module 2.4 Flashcards
Enzymes
Role of enzymes
Catalyse reaction without being used up
Lower activation energy
Catalase role
Catalyses the break down of hydrogen peroxide into water and oxygen
Intracellular
Amylase role
Catalyses the break down of starch into maltose
Extracellular
What is specificity
The shape of the active site of the enzyme is complimentary to the shape of the substrate it is highly specific so will only catalyse reaction with the particular substrate that fits into the active site
lock and key hypothesis
Substrate fits into active site as they are complimentary shapes
bind forming enzyme substrate complex
product leaves the active site
Induced fit hypothesis
When the substrate enter the enzyme it causes a slight change in the shape so the conformation to the substrate is more precise
this allows the substrate to bind more effectively to the active site
enzyme-substrate complex
The product is formed but it has a slightly different shape to the substrate so detaches from the active site
Order of product formation
substrate, enzyme-substrate complex, enzyme-product complex, product
How enzymes catalyse reactions
Lower the activation energy by bringing the substrate molecules close enough together to react without excessive heat
Effect of pH
H+ and OH- ions break ionic bonds and H bonds in the tertiary structure causing the enzyme to denature when not at optimum pH
Effect of temperature
Kinetic energy from heat breaks H bonds in the tertiary structure
Enzyme denatures when over kinetic energy
Below optimum temperature rate of reaction is slower as there is less movement from kinetic energy so less collisions to form ES complexes
Effect of enzyme concentration
Rate of reaction will increase as concentration increases until substrate is limiting factor when rate will level off as all substrate molecules will have been turned into their product
Effect of substrate concentration
Rate of reaction will increase as concentration increases until enzyme is limiting factor when rate will level off as all enzyme active sites will be occupied
temperature coefficient (Q10) equation
rate of reaction at (T+10 degrees) / Rate of reaction at T degrees
What are coenzymes
small organic non-protein molecules that bind temporarily to the active site just before or at the same time as the substrate
They are chemically changed in the reaction
What are cofactors
small non-protein molecules that some enzymes need to work
