Enzymes Flashcards
What are enzymes?
Enzymes are biological catalysts that speed up metabolic reactions in living organisms.
How would you speed up a chemical reaction in a laboratory setting?
• Raising the temperature
• Increasing the pressure
Define anabolic
These reactions build up or synthesise large polymers.
Eg. Cellulose for cell walls
Define catabolic
These reactions break down large organic molecules
Eg. Digestion of organic material such as starch to its monomer glucose
Where do enzymes function?
Intercellularly and extracellularly
Why are enzymes important?
In order to sustain life chemical reactions must occur rapidly. Without enzymes they would occur too slowly.
The number of reactions that an enzyme molecule can catalyse per second is called its __________ _______.
Turnover number
What type of protein are enzymes?
Enzymes are globular proteins
This means they are soluble in water because of the hydrophilic nature of the side groups of their amino acids.
What happens to catalysts after the reaction?
Catalysts remain unchanged and can be used again
Give examples of digestive enzymes
Protease
Amylase
What does protease digest?
Proteins
What does carbohydrase digest?
Carbohydrates
What does lipase digests?
Lipids
What does cellulase digests?
Cellulose
What is catalase?
Catalase is an intracellular enzyme that protects cells from damage by breaking down hydrogen peroxide to water and oxygen.
Why do white blood cells use catalase?
White blood cells use catalase to kill microbes once they are ingested.
What is a metabolic pathway?
A metabolic pathway is a series of consecutive reactions with each step being catalysed by a different enzyme that is specific for the substrate produced.
What happens to the metabolic pathway if one enzyme can’t function?
If one enzyme can’t function, the metabolic pathway cannot run
What are the reactants, intermediaries and products known as?
Metabolites
Are metabolic pathways anabolic or catabolic?
They can be both anabolic and catabolic
What is the name of the energy required for a reaction to start?
Activation energy
Name two examples of metabolic pathways
Respiration and photosynthesis are both examples of complex metabolic pathways
How does enzyme concentration affect the rate of reaction?
As the enzyme concentration increases so does the rate of reaction as substrates have more active sites to bind to
How does substrate concentration affect the rate of reaction?
As substrate concentration increases so does the rate of reaction as more enzyme-substrate complexes are formed
What is an enzyme inhibitor?
An inhibitor slows down or stops a reaction by affecting the binding of substrates to enzymes.
Can be reversible and irreversible
How do reversible inhibitors work?
They bind to the active site through hydrogen bonds and weak ionic interactions therefore they don’t bind permanently
What are competitive inhibitors?
They are similar in structure to the substrate molecule therefore they can bind to the active site of an enzyme.
They decrease the activity as the compete with substrates for the active site however they don’t affect the yield of product formed
What are competitive inhibitors?
They are similar in structure to the substrate molecule therefore they can bind to the active site of an enzyme.
They decrease the activity as the compete with substrates for the active site however they don’t affect the yield of product formed
What are non-competitive inhibitors?
They don’t bind to the active site but instead bind to the allosteric site.
Binding of non-competitive inhibitors change the shape of the active site affecting the binding of the substrate
What are coenzymes?
They are organic cofactors which do not bind permanently. They facilitate the binding of substrate to enzyme
What conditions affect the rate of enzyme-controlled reactions?
Temperature
pH
Enzyme conc.
Substrate conc.
What are the difference between reversible and non-reversible inhibitors?
Reversible means the inhibitor can be removed whereas non-reversible means the inhibitor cannot be removed from the enzyme
What is end-product inhibition?
The products of some reactions can act as reversible inhibitors for the enzymes involved, controlling the reaction
