Enzymes Flashcards
What is metabolism
the combination of all the chemical reaction in the body, that occur in sequences called metabolic pathways
What are anabolic reactions
They build up large molecules from smaller ones, eg, glucose into starch
What are catabolic reactions
They break down large molecules into smaller ones, eg, proteins into amino acids
What are intracellular enzymes
They work inside the cell
What are extracellular enzymes
They work outside the cell
Enzymes are proteins with what type of structure and therefore are held in shape by what type of bonds
They have a tertiary structure and can therefore be held together by hydrogen, ionic and disulphide bridge bonds
What are thermostable enzymes
Enzymes that are more resistant to high temperatures
How do enzymes work
They lower the activation energy needed for a reaction to occur making it easier to start a reaction
What effect does temperature have on enzyme-controlled reactions
It speeds them up initially as the kinetic energy is increased. Then as it gets hotter the active site is weakened and the reaction slows rapidly
What are thermophilic bacteria
Bacteria with enzymes that are highly thermostable
What are acidophile bacteria
Bacteria that can survive pH 1
What effect does the concentration of substrate have on enzyme-controlled reactions
A greater concentration increases the rate of reaction before plateauing as all the active sites are occupied
What is competitive inhibition and give an example
Where a molecule that is a similar shape to the substrate fits the active site of an enzyme and prevents the substrate being broken down. For example, methanol inhibits ethanol being broken down by alcohol dehydrogenase
What is non-competitive inhibition and give an example
When a molecule binds to an enzyme somewhere other than the active site and changes the shape of the active site so the substrate not longer fits. For example, potassium cyanide binds to cytochrome oxidase and prevents respiration reactions
What is end-product inhibition and give an example
Where the end product in a metabolic pathway is an inhibitor for another stage of the pathway, stopping more product being created. For example, ATP is capable of inhibiting stage 1 of the respiratory metabolic pathway
What is an allosteric enzyme
They only work if an activator molecule attaches to it and causes the active site to change shape to accommodate a substrate
What is a buffer
Used to maintain a constant pH in enzyme-controlled reactions
How are enzymes immobilised
By trapping them in a large, insoluble matrix or in a mesh.
What are the benefits of using immobilised enzymes
Less likely to denature
Are more thermostable
Easy to recover and reuse after a reaction
Allows you to easily add or remove enzymes giving you greater control over a reaction
How do biosensors work
Enzymes can detect the presence of specific molecules in a mixture. They produce a chemical signal which, when connected to an electrical device is able to produce an electrical impulse which is proportional to the concentration of the molecules in the mixture.
What are biosensors used for
Blood glucose monitors used by diabetics
What are the two possible structures for the enzyme-substrate complex
Induced fit and lock & key
