Enzymes Flashcards
Why are enzymes called biological catalysts?
They increase the rate of metabolic reactions in living organisms, by lowering the activation energy
What are some features of a ‘catalyst’
Catalysts remain unchanged at the end of a reaction, and can be used again
A small amount of catalyst can convert a lot of substrate molecules into product molecules
What is meant by a metabolic pathway?
A series of consecutive reactions, each step catalysed by a specific enzyme that produces a specific product
What is a catabolic pathway?
Metabolites are broken down into smaller molecules and energy is released
What is an anabolic pathway?
Energy is used to synthesise larger molecules from smaller ones
What are extracellular enzymes? Give two examples.
Enzymes that are secreted and work outside of the cell
Amylase in the salivary glands
Trypsin in the pancreas
What is a prosthetic group? Give an example.
A cofactor that is permanently bound by covalent bonds to an enzyme.
Zinc ion in carbonic anhydrase
What is a cofactor?
The general term for a substance that has to be present to ensure an enzyme reaction occurs at the appropriate rate (these can include prosthetic groups or coenzymes)
What is a coenzyme?
Organic non protein molecules that bind temporarily to the active site
Explain the lock and key hypothesis
The tertiary structure of the enzymes active site is complimentary to the substrate molecules
Why is the induced fit hypothesis widely recognised as a more accurate representation?
It suggests the active site is not a fixed rigid shape
The active side is flexible and ‘moulds’ itself around the substrate for a more effective binding
