BIO.A.2.3 Enzyme Regulation of Biochemical Reactions BIO. A.2.3.1 Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction. BIO.A.2.3.2 Explain how factors such as pH, temperature, and concentration levels can affect enzyme function.

Chemical Reactions A chemical reaction is a process that transforms one set of chemical substances to another. Atoms are never gained or lost, just rearranged. Reactants – enter into the chemical reaction. Reactants are on the left side of the arrow. Products – are produced as a result of the chemical reaction Products are on the right side of the arrow.

Endothermic and Exothermic Reactions Endothermic chemical reactions absorb energy. 6CO2 + 6H2O → C6H12O6 + 6O2 (ENERGY ABSORBING) Exothermic chemical reactions release energy. C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ENERGY RELEASING)

Activation Energy Just like it sounds. Activation Energy is the energy required to initiate or start a chemical reaction.

ridding the body of waste. Catalysts and Enzymes Catalysts are substances that lower activation energy required to initiate chemical reactions. Enzymes are biological protein catalysts used by cells to initiate and control specific chemical reactions. Enzymes are specialized protein molecules facilitating most of the body’s metabolic processes – such as: supplying energy, digesting foods, purifying your blood, ridding the body of waste.

Why Do We Need Enzymes? Reactions with enzymes are up to 10 billion times faster than those without enzymes. Enzymes typically react with between 1 and 10,000 molecules per second.  Fast enzymes catalyze up to 500,000 molecules per second.

Enzyme - Substrate Complex Enzymes bind to specific reactant molecules called substrates at a location called the active site. Together, they fit like two puzzle pieces or a lock & key.

BIO. A.2.3.1 Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction.

Carbon dioxide is a waste product of cellular respiration. BIO. A.2.3.1 Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction. Carbon dioxide is a waste product of cellular respiration. The enzyme carbonic anhydrase converts the substrates CO2 and H2O into H2CO3 carbonic acid. In the lungs the reaction is reversed and the CO2 is exhaled. Carbon Dioxide in the Bloodstream

Catalase Enzyme 2 H2O2 → 2 H2O + O2 Hydrogen peroxide is a harmful byproduct of many normal metabolism. To prevent damage to cells and tissues, it must be quickly converted into a less dangerous substance. Catalase is used by cells to rapidly breakdown hydrogen peroxide into less-reactive oxygen gas and water molecules. Enzymes are very specific, generally catalyzing only one chemical reaction.

Enzymes are never used up in chemical reactions. They can immediately bind with another substrate.

What suffix do most enzymes have in common?

BIO. A.2.3.1 Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction.

BIO.A.2.3.2 Explain how factors such as pH, temperature, and concentration levels can affect enzyme function. Temperature, pH, and regulatory molecules are all factors that can affect the activity of enzymes. Enzymes produced by human cells generally work best at temperatures close to 37°C, the normal temperature of the human body. Enzymes work best at certain pH values. For example, the stomach enzyme pepsin, which begins protein digestion, works best under acidic conditions. The activities of most enzymes are regulated by molecules that carry chemical signals within cells, switching enzymes “on” or “off” as needed

Substrate Concentration At lower concentrations, the active sites on most of the enzyme molecules are not filled because there is not much substrate.  Higher concentrations cause more collisions between the molecules.  With more molecules and collisions, enzymes are more likely to encounter molecules of reactant. The maximum velocity of a reaction is reached when the active sites are almost continuously filled. Reaction rate therefore increases as substrate concentration is increased but it levels off.

Enzyme Concentration If there is insufficient enzyme present, the reaction will not proceed as fast. Additional active sites could speed up the reaction. As the amount of enzyme is increased, the rate of reaction increases. If there are more enzyme molecules than are needed, adding additional enzyme will not increase the rate. Reaction rate therefore increases as enzyme concentration increases but then it levels off.

Higher temperature generally causes more collisions among the molecules and therefore increases the rate of a reaction. More collisions increase the likelihood that substrate will collide with the active site of the enzyme, thus increasing the rate of an enzyme- catalyzed reaction. Above a certain temperature, activity begins to decline because the enzyme becomes denatured. The rate of chemical reactions therefore increases with temperature but then decreases. Temperature

Optimal Ranges Since enzymes are specific for a certain reaction, they have optimal temperature and pH values in which they function best.

Denaturation = Loss of Shape = Loss of Enzyme Activity Enzymes can become denatured at high temperatures (>37⁰C). Enzymes can also be denatured by extreme pH levels.

How are enzymes influenced by:. Temperature. pH How are enzymes influenced by: *Temperature * pH *Substrate Concentration?

Substrate Concentration At low values, the effect on enzyme activity: When does increasing the substrate concentration have no effect?

Enzyme Concentration At low values, the effect on enzyme activity: When does increasing the enzyme concentration have no effect?

How Does Temperature Affect Enzyme Activity? Increasing the Concentration of Substrate How Does Temperature Affect Enzyme Activity? At low values, the effect on enzyme activity: Beyond what temperature in humans do increases have a different effect?

What is the effect of high temperatures on enzyme molecules? Increases in temperature and concentration have what underlying physical cause in common? High temperatures cause enzyme molecules to change their shape, or denature, thus altering the shape of the active site so that it no longer fits the substrate. A denatured cannot catalyze reactions.

Competitive Inhibitors complete for the Active Site and halt the chemical reaction when sufficient product has been made.

BIO.A.2.3.2 Explain how factors such as pH, temperature, and concentration levels can affect enzyme function.