SPEC POINT 2.10 Flashcards
(14 cards)
What is an enzyme?
A biological catalyst that speeds up the rate of reaction by reducing the activation energy of reactions
What is the structure of an enzyme?
Globular protein with an active site and charged R groups on the outside of molecules (hydrophilic)
Why are enzymes described as biological catalysts?
They are proteins which reduce the activation energy of biological reactions
What is the effect of changing enzyme concentration on the initial rate of reaction?
Enzymes reduce activation energy. Active sites of enzymes become occupied but as substrate concentration decreases it becomes the limiting factor as not all active sites are occupied.
What type of protein is an enzyme?
Globular, with complex tertiary structure
What is the difference between intercellular and extracellular proteins?
Intercellular - produced and function inside cell
Extracellular - secreted by cells and catalyse reactions outside cells
How do enzymes reduce activation energy?
By providing an alternative reaction pathway
How can pH and temperature alter enzyme activity?
They can alter protein structure and change the shape of the active site - denaturation
What must happen for a reaction to occur between the substrate and active site of an enzyme?
Substrates must collide with the active site at the correct orientation and speed in order for a reaction to occur
What creates enzyme specificity?
The complementary nature of the active site and substrate
What determines the shape of the active site of an enzyme, and what can alter this (apart from temp and pH)?
Determined by the complex tertiary structure of the protein
If the tertiary structure is altered in any way (different polypeptide chain sequence), the active site will change and the substrate will not fit
What is the lock and key theory?
The theory that the substrate fits exactly into the active site
What is the induced fit theory?
The enzyme and its active site (and sometimes substrate) can change shape slightly as the substrate molecule enters the enzyme
Conformational change
How does the induced fit theory maximise the ability of the enzyme to catalyse a reaction?
Conformational change
Ensures an ideal binding arrangement between the enzyme and substrate
