Enzymes Flashcards
What are enzymes?
globular proteins that act as biological catalysts
How does an enzyme act as a biological catalyst?
alter rate of chemical reaction by lowering activation energy required without undergoing permanent change themselves
What is required to start a chemical reaction?
-must collide with sufficient energy
-energy of products must be lower than substrates/reactants
-minimum amount of energy to start reaction-activation energy
What is the structure of an enzyme?
Specific region- active site
What is an active site?
forms small depression within the much larger enzyme molecule
What is the active site made up of?
relatively small number of amino acids
What is the molecule that the enzyme acts upon called?
substrate
What is formed when the active site and substrate collide?
enzyme-substrate complex
How is an enzyme substrate complex formed?
substrate and active site collide
substrate held within active site that temporarily form bonds between certain amino acids of substrate and active site
What does the lock and key enzyme model suggest?
enzyme active site specific shape to particular substrate
enzyme active site and substrate are exactly complimentary
when substrate collides with active site an enzyme substrate complex is formed
What does the enzyme induced fit model propose?
active site and substrate not EXACTLY complimentary
active site forms as enzyme and substrate interact
proximity of substrate alters shape to form functional active site
enzyme moulds itself around substrate
enzyme substrate complex is formed
What two changes are most frequently measured to determine the length of enzyme-catalysed reactions?
-formation of products
-reduction in starch concentration
How can we measure the change in a rate of reaction?
measure gradient at chosen point
How can we obtain a gradient from an enzyme-catalysed reaction ?
equal to gradient of tangent to curve at point
tangent- point at which straight line touches the curve without cutting across it
normal line- line that pass through a point at 90•
gradient- A/B
How do we create a control when measuring the rate of an enzyme-catalysed reaction?
enzyme and substrate concentration constant
all possible inhibitors absent
active site and substrate mustn’t be complementary