Enzymes study

enzyme-substrate specificity

enzyme-substrate specificity

- active site has a complementary shape to the substrate
- enzymes are very specific to the substrates they can bind to

Enzymes

Catalysts (speed reactions up, reduce activation energy) for chemical reactions in living things

Intracellular enzymes

enzymes that catalyse reactions within the cell

Extracellular enzymes

Enzymes released by cells. They work and function outside of cells

How do enzymes work?

- Substrate collides with the active site of an enzyme, making it slightly change shape.
- The shape of shape puts a strain on the substrate molecule, weakening bonds in the enzyme, reducing activation energy.
- This facilitates the transformation of the substrate into product(s) more rapidly and efficiently.
- Once the products leave the enzyme, it goes back to its original shape.

anabolic reactions

building larger molecules from smaller ones.
eg. protein synthesis (amino acids to build a protein)

catabolic reactions

breaking larger molecules into smaller ones.
eg. digestion

What is needed for a substrate molecule and an active site to come together?

Movement

Enzymes can be immobilized by

being embedded in membranes.
eg. respiration

denaturation

hydrogen/ionic bonds weaken and start to break, changing the shape of the active site, therefore substrate molecules can no longer bind to the active site

activation energy

the minimum amount of energy required to start a chemical reaction

temperature effect on rate of reaction

-increasing temperature increases kinetic energy of the particles
- particles move faster and therefore have more frequent and successful collisions between the active site of the enzyme and substrate molecules.
- faster rate of reaction
-increasing temp above optimum denatures the enzyme

ph effect on rate of reaction

- Every enzyme has optimal pH.
- If the pH is too low or too high, the charges on the amino acids of the enzyme can be affected. This causes ionic bonds or hydrogen bonds within the enzyme to be weakened or broken. When these bonds are affected, the enzyme becomes denatured. Making the enzyme fail to function or work less efficiently, meaning less enzyme activity and thus, a lower rate of reaction.
- The closer the pH is to the enzyme's optimum range, the higher the rate of reaction. At the pH levels that are further away from the optimum, the rate of reaction decreases.

substrate concentration effect on rate of reaction

- increasing substrate concentration leads to a higher collision rate with the active sites of enzymes.
- rate of reaction increases to a maximum rate when all of the active sites are occupied by substrate molecules. (The enzyme is saturated and is working at its maximum reaction rate)