Enzymes Chemical Reactions

Characteristics of Enzymes (Catalysts) Are specific for their job! Work in chemical reactions. Only work for a short time. Do not change in a chemical reaction! But, causes others to change in a reaction. Enzymes are used over & over & over again (reused)! Speed up reactions!!!!!!! !! Made by the cells of organisms ** Most enzymes are made of proteins.

Lock & Key Model (Active Site)

Enzymes Have A SPECIFIC SHAPE. This allows them to have SPECIFIC FUNCTIONS!!!!!!!!!!!!!!!!!!!!!!!! KEY IDEA

Lock & Key Model Substrate – the reactant that binds with the enzyme. Substrate Enzyme – special proteins that speed up a reaction. Also, called a catalyst. Enzyme-Substrate Complex – when the substrate binds to the enzyme. Active Site Active Site – the part of the molecule where the substrate fits into the enzyme.

Enzymes Enzymes act like a scissor (break down particle).

1. Digestion - break down food 2. Synthesis- build up Functions of Enzymes (Catalysts)

More Key Ideas Enzymes are also called catalysts. Enzymes end in –ase. Enzymes are organic molecules made of proteins. Enzymes are written above the arrow for equations. Reactants Products (combined) (formed) Catalase (enzyme)

Why is the SHAPE of ENZYMES Important? An enzymes SHAPE determines its specific FUNCTION. If the shape is incorrect, the enzyme will NOT work or the reaction will SLOW down or STOP!!!!!

SHAPE = SPECIFIC FUNCTION ENZYMES ARE VERY SPECIFIC AND ONLY WORK WITH CERTAIN SUBSTRATES

Examples: Maltase – breaks maltose into 2 glucose molecules. Lipase – breaks down fat Sucrase– breaks down sucrose into 2 simple sugars Lactase– breaks down the sugar in milk into 2 simple sugars Protease – breaks down peptide bonds in proteins Enzymes end in –ASE

Lock and Key Sucrose Glucose Fructose Dehydration Synthesis or Hydrolysis? ____________________ Hydrolysis

Do Now 2. An example of synthesis or digestion? 1. An example of synthesis or digestion?

Factors that Affect Enzyme Reactions 1. Enzyme Concentration 2. Temperature 3. pH **least affected by light & CO 2 **

Enzyme Concentration More enzymes = faster rate of reaction. Eventually rate stops going faster because there is no more extra enzymes.

Enzyme Concentration When all substrates are used up, the rate is limited because no more enzymes to bind with. Small amount of enzymes limit the reaction rate.

Temperature At the optimum (best) temp, enzymes function at the highest rate (faster). Optimum temp 98.6° F (36 C) (human enzymes). Reaction rate speeds up till it reaches its’ optimum rate then slows down, shape changes, & breaks apart. Active site shape changes = No enzyme function (DENATURATION)

pH Changing pH, changes the H-bonds and the shape changes! When shape changes then enzyme action stops (denaturation)! Optimum pH for most enzymes Stomach enzyme (pepsin) works best at 2-3 pH. Small intestine enzymes work best at a pH of 8.