Enzymes Flashcards
How are metabolic pathways controlled?
By the presence and absence of particular enzymes
How do reactions start?
Chemical reactions involve the breaking and formation of bonds. Therefore energy is required to start a reaction (to initially break the bonds), this is known as the activation energy (EA).
What do enzymes do to reactions?
They lower the activation energy, as such meaning less energy is required to start it - consequently the reaction can occur quicker and more efficiently.
What happens once the activation energy is reached?
A transition state is reached
Enzymes work by -
Lowering the activation energy
Bring the substrates closer together to allow the reaction to happen
Induced fit model
The enzyme active site is not rigid, it is a flexible structure. The shape of the active site alters slightly to better fit the substrate, initially the shapes are complementary not an exact fit.
Induced fit ensures the active site comes in close contact with the substrate increasing the chance of the reaction taking place.
Enzyme substrate affinity
The substrate molecules are chemically attracted to the active site of the complementary enzyme - they have a high affinity for it.
The products form after the reaction do not, so they are free to leave the active site
How does the enzyme help when there are multiple substrates involved?
The active site will change shape and orientate the substrate in the right way for the reaction to occur
Tracking enzyme activity
Can be tracked by either the decrease in the substrates or increase in the products
Eg volume of gas produced
Changes in pH
Colour changes
