Structure And Function Of Enzymes Flashcards
(16 cards)
What is an enzyme?
A biological catalyst that speeds up metabolic reactions.
Enzymes facilitate biochemical reactions in living organisms.
What type of molecules are enzymes?
Globular proteins with a precise 3D shape due to ionic, hydrogen, disulphide bonds and hydrophobic interactions of the tertiary structure.
The unique structure of enzymes is crucial for their function.
What is an active site?
The portion of the enzyme molecule to which the substrate binds.
The active site is critical for enzyme specificity and function.
What is an anabolic reaction?
The building up of molecules.
Anabolism requires energy input to synthesize complex molecules from simpler ones.
What is a catabolic reaction?
The breakdown of molecules.
Catabolism releases energy by breaking down complex molecules.
What is activation energy?
The amount of energy needed to initiate a reaction.
Activation energy is a crucial factor in determining the rate of a chemical reaction.
What effect do enzymes have on activation energy of a reaction?
Enzymes lower the activation energy.
This allows reactions to proceed more quickly and efficiently.
What is the benefit to living organisms of having enzymes?
Enzymes allow reactions to take place at body temperature at the rapid rate necessary to sustain life.
Without enzymes, many biochemical reactions would occur too slowly to support life.
Describe how an enzyme works in a catabolic reaction.
Substrate collides with enzyme and fits into the active site forming an enzyme-substrate complex. The bonds with the substrate are strained lowering the activation energy and forming the product. The product does not fit into the active site and is released from the enzyme. The enzyme can be reused.
This process illustrates the catalytic action of enzymes in facilitating breakdown reactions.
What does the term ‘enzyme specificity’ mean?
Each enzyme is specific to a particular substrate. Only one substrate is the exact complementary shape to the active site.
This specificity is crucial for the regulation of metabolic pathways.
What is the ‘lock and key hypothesis’?
The enzyme active site is an exact match to the shape of the substrate, they are complementary to each other.
This hypothesis explains how enzymes interact with substrates to catalyze reactions.
What is the ‘induced fit hypothesis’?
The active site moulds around the substrate forming a precise fit.
This hypothesis explains how enzymes adjust their shape to better accommodate substrates.
What is a co-factor?
A non-protein substance that an enzyme may require to function.
Some cofactors are permanently attached to the enzyme.
Name some examples of cofactors.
- Metal ions e.g. Chloride ion in salivary amylase
- Prosthetic groups e.g. haem group in catalase
Cofactors can be metal ions or organic molecules that assist in enzyme activity.
What is a co-enzyme?
Co-enzymes are non-protein, organic molecules necessary for enzyme action.
Co-enzymes are never permanently attached to the enzyme.
Give some examples of coenzymes.
- NAD
- FAD
NAD and FAD are co-enzymes involved in cellular respiration.
