U3 AOS 2

• Biochemical reactions are reactions occurring in cells that lead to the formation of a product from a reactant
• A biochemical pathway is a series of linked biochemical reactions that start with an initial reactant that is converted to a final product.
• metabolism is the total of all chemical reactions occurring in an organism.
• An enzyme is a protein that acts as a biological catalyst, speeding up reactions without being used up.
• A reactant is a substance that is changed during a chemical reaction.
• A product is the compound that is formed during a chemical reaction.
• A substrate is the compound on which the enzyme acts.
• In anabolic reactions complex molecules are built from simple molecules.
• Endergonic reactions are energy-requiring.
• In catabolic reaction complex molecules are broken down into simple molecules.
• Exergonic reactions are energy-releasing.
• A catalyst is a factor that causes an increase in the rate of a reaction.
• Activation energy is the minimum amount of energy required to initiate a chemical reaction.
• The active site is the region of an enzyme that binds temporarily with the specific substrate of the enzyme.
• Cofactors are a non-protein molecule or ions that is essential for the normal functioning of some enzymes.
• Coenzymes are an organic molecule that act with an enzyme to alter the rate of reaction.
• Loaded: The form of coenzymes that can act as electron donors.
• Unloaded: The form of coenzymes that can act as electron acceptors.
• Optimum temperature is the temperature at which the rate of reaction catalyzed by an enzyme is at its highest.
• Factors that can affect enzyme activity:

  • temperature
  • pH
  • substrate concentration
• Competitive inhibitors bind to the active site of an enzyme, preventing substrates from binding.
• Competitive inhibition is inhibition in which a molecule binds to the active site of a molecule instead of the usual substrate.
• Non-competitive inhibition is inhibition in which a molecule binds to the allosteric site of an enzyme causing a conformational change in the enzyme so it cannot bind with the substrate and produce a product.
• The allosteric site is a location on an enzyme molecule where a compound can bind and alter the shape of the enzyme.
• Allosteric regulation is the control of the rate of reaction of enzymes through conformational changes in enzymes.
• feedback inhibition  occurs when the end product of a pathway inhibits an enzymes earlier in the pathway as a negative feedback mechanism; also known as end-product inhibition.
• Allosteric inhibitors are molecules that bind to the allosteric site of an enzyme and stop enzyme activity.
• Allosteric activators are molecules that bind to the allosteric site of an enzyme and increase enzyme activity.