Enzymes
Globular proteins that catalyze nearly all the chemical reactions in living things.
Why are they essential to life
Because they allow chemical reactions to occur rapidly and efficiently without having to increase the temperature of the system.
substrate
a reactant acted on by an enzyme
The activity of an enzyme depends on what
its 3D shape: tertiary structure
The shape of the enzyme is denatured
it no longer has its catalyzing ability
Equation of an enzyme catalyzing a reaction
Enzyme + substrate Enzyme-subsstrate——>enzyme + product
Why do some plants and vegetables turn burn when peeled or sliced
Due to a formation of a class of compounds called quinones by damaged plant cells
One function of quinones
protect the interior of the potato from invasion by soil microorganisms. Th brown patch not only seals the damaged area but is toxic to most microbes.
If large amounts of quinone is toxic to the plant how does the plant survive.
In addition to cellulose, the cell walls of potatoes contain catechol
Catechol
Is a chemical when exposed to oxygen converts to quinone. However this process happens too slowly to be of any use to the damaged potato
The mechanisms that allow catechol to become quinone faster
The cytoplasm of potato cells contains a enzyme ( polyphenol oxidase or PPO) that speeds up the conversion.
In an undamaged potato the PPO remains inside the cell in the cytoplasm and the catechol is outside. When the cell is damaged the cytoplasm leaks out allowing the PPO to come into contact with the catechol and catalyze the conversion to quinone
The equation of the conversion to quinone
Enzyme (PPO) +substrate (CATECHOL) (enzyme-substate)—> enzyme( PPO)+ product(QUINONE) (brown color)
The activity of any enzyme can be measured by
detecting the product of the reaction catalyzed by the enzyme.
When a yellow/ brown color is seen what does it mean
that a reaction has occurred
the color f a quinone molecule is
a faint copper color, however, the intensity of the color is proportional to its concentration ( the darker the solution the more product present
