Biochemical Reactions B-2.8Explain the factors that affect the rates of biochemical reactions (including pH, temperature, and the role of enzymes as catalysts).

Biochemical Reactions Allows organisms to grow, develop, reproduce, and adapt. – A chemical reaction breaks down some substances and forms other substances.

Factors that affect the rates of biochemical reactions: 1.Chemical reactions have to have sufficient amounts of energy in order to take place. – Activation energy—the amount of energy needed to cause a chemical reaction Some reactions must absorb energy for a reaction to start—comes in the form of heat. Heat and light can be given off as a result of a reaction – Ex-cellular respiration or bioluminescence

Factors that affect the rates of biochemical reactions: 2.Changes in temperature – Gaining or losing heat 3.Most organisms have to have a very narrow pH range for cell processes to take place. – Buffers—used to regulate pH homeostasis in a cell – Small changes in pH disrupts cell processes

Factors that affect the rates of biochemical reactions: 4.Catalysts-speeds up the rate of a chemical reaction. – Allows a chemical reaction to activate at a lower than normal temperature. – Lower the activation energy of a chemical reaction – Is not altered during the chemical reaction

Factors that affect the rates of biochemical reactions: – Enzymes-proteins that serve as catalysts in living organisms. Enzymes are specific—can only catalyze one chemical reaction by working on one specific substrate (reactant) Involved in many of the chem. reactions necessary for organisms to live, reproduce, and grow. – Ex-digestion, respiration, reproduction, movement, cell regulation Enzyme structure can be changed by temperature and pH which means they work best at specific temps. and pH’s.

Activation Energy Enzymes lower the activation energy of a chemical reaction, making it occur more easily and quickly.

Enzymes are highly specific protein molecules based on shape. – Each enzyme shape only fits a specific molecule – If the shape of the enzyme changes, it will no longer function.

LE 5-16 Substrate (sucrose) Enzyme (sucrose) Fructose Glucose