ENZYMES Flashcards
(41 cards)
Define active site
Indented area on surface of enzyme molecule
Complementary shape to substrate molecules
Define catalyst
Chemical that speeds u the rate of reaction and remains unchanged and reusable at the end of the reaction
Define metabolism/metabolic
Chemical reaction that takes place inside living cells or organisms
Define product
Molecule produced from substrate molecule by an enzyme
Define substrate
Molecule that is altered by an enzyme catalysed reaction
Define metabolites
Reactants immediate and products in enzyme controlled reactions
What type of protein are enzymes?
Globular
Shape determined by tertiary structure
What does intracellular mean?
Enzymes work inside cells, most catalysing reactions that occur in series
What does extracellular mean?
Enzymes work outside the cells, catalysing hydrolysis reactions to break down macromolecules into small, soluble molecules that can be absorbed `
What is an example of intracellular enzymes?
Catalase protects cell from damage by reactive oxygen by breaking down hyperovide into water and oxygen
What is an example of extracellular enzymes?
Amylase- salivary glands, digest starch into maltose
Trypsin- pancreas acts in lumen of small intestines to digest proteins into smaller peptides by hydrolysing peptide bonds
How do enzymes work?
Speed up metabolic reactions
Enzymes make substrates into products and the reactions are either:
Catabolic- substrates broken down
Anabolic- substrate joined to form larger product
What does lactase break down into?
Glucose and galactose monomers
What does catalase break down down?
Hydrogen peroxide to water and oxygen
What is rubisco catalyse?
Binding of carbon dioxide to ribulose biphosphate in plants
What is activation energy?
Energy stored in bonds between atoms
Allow reactions= bonds break
Activation energy required
How is an anabolic reaction started?
If two molecules need to be joined, attaching to the enzyme holds them close together, reducing any repulsion between the molecules so they can bind more easily
How is a catabolic reaction started?
If enzyme is catalysing a breakdown reaction, fitting into active site puts strain on bonds in substrate
Strain means substate molecule breaks up more easily
What is meant by lock and key?
Complementary shape of active site and substrate molecule are like lock and key Enzyme + substrate enters active site Enzyme-substrate complex Enzyme-product complex Product (older model)
What its mean by induced fit?
Enzymes active site changes slightly upon collisions, active site fits closer to substrate Substate entering active site or enzyme Enzyme-substrate complex Enzyme-product complex Product leaving active site or enzyme
What is the kinetic energy and collision theory?
- KE means collisions happen at random
- as fluid heated= more KE= molecules move faster= more frequent collisions
- collisions occur with more energy (travelling faster) so collide with a greater force
- enzyme-substrate complexes only form when substate molecules collide with active site of enzyme
- if KE of both molecules has increased, there will be more collisions= increase rate of reaction and more product formed
What is denaturation?
Where the tertiary structure of enzyme is changed to the point that the enzyme doesn’t work
What is the effect of heating?
- molecules vibrate, vibrations strain bonds holding molecule together
- vibrations can break hydrogen and ionic bonds
- said bonds are vital in keeping active site shape and tertiary structure
- as heat increases, more bonds break and thus lowers the rate of reaction
What is the formula for working out the rate of reaction?
1/time taken to reach end point
