Enzymes Flashcards
What are enzymes?
They are globular tertiary proteins with a 3D structure. They are biological catalysts and lower the activation energy nor reactions both intracellular and extracellular.
What is activation energy?
The energy needed (that must be overcome) to activate a reaction
What are active sites?
A specific region of the enzymes is functional, this is the active site, substrates fit into these active site and they are very specific. The substrate molecules must have a complementary shape to the a active site.
What are active sites made up of?
Amino acids.
What happens what a substrate and enzyme join?
When a substrate molecule forms with the enzyme it forms an enzyme-substrate complex, this occurs by the induced fit theory.
What’s the induced fit theory?
This theory suggests that the active sites form as the enzyme and substrate interact. The enzyme is flexible and can mould around the substrate. The enzyme has a general shape which alters in the presence of the specific substrate. As the shape changes it puts strain on the substrate molecule. This strain distorts a particular bond or multiple bonds in the substrate which lowers the activation energy needed to break the bond.
What are changes in the enzymes environment likely to do?
Change its shape.
How is the dipeptide formed?
Two amino acids join in a condensation reaction to make a dipeptide, a water molecule is lost in this.
What’s the primary structure of enzymes?
The order of the amino acids, this order determines the function of the protein, the type and position of bonds do this.
What’s the secondary structure of enzymes?
Where the polypeptide chain folds or coils into an alpha helix or beta pleated sheet, these are made by hydrogen bonds.
What’s the tertiary structure of enzymes?
Further folding or coiling and these are held together by hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interactions.
What effects the rate of reaction?
Temperature pH Substrate concentration Enzyme concentration Competitive inhibitors Non-competitive inhibitors
How is the rate of reaction effected at a low temperature?
At a low temperature the rate of reaction is low, there is not much kinetic energy so the molecules are moving slowly causing few successful collisions.
How is the rate of reaction effected at the optimum temperature?
At the optimum temperature the rate of reaction is high. There is more kinetic energy so the molecules are moving fast causing many successful collisions.
How is the rate of reaction effected at a high temperature?
At a high temperature the rate of reaction is low. There is too much kinetic energy increasing the vibrations in the molecule, this cause the hydrogen bonds in the molecule to break, changing its structure and denaturing it.
