Bellringer What were the 2 food-based chemical reactions we studied in yesterday’s experiment? What are the proteins that speed up metabolic reactions called?
Agenda Collect LAB: Exploring Enzymes NOTES: Enzymes Shape, Function, and Naming Factor’s that slow enzymes Activation Energy
Enzymes & Substrates Enzymes are proteins that catalyze (speed up) chemical reactions in the body The molecules that are affected by enzymes are called substrates Example: Amylase is an enzyme in saliva that breaks down starchy foods like bread and pasta. In this case, starch is the substrate of amylase.
Summary of Enzyme Properties Shape: Enzymes are globular (balled up) proteins Function: Enzymes work by temporarily bonding with substrate molecules Reusable: A single enzyme can be used multiple times Name: Enzymes are named for the substrates they affect
Shape of Enzymes Substrate Enzyme Active Site Enzymes are long protein chains that are “knotted up” like a ball of yarn. The surface of an enzyme has a small pocket called the active site which is shaped to bind substrate molecules.
How enzymes work Substrate molecules temporarily bond with the enzyme at the active site. The enzyme bends the substrate in a way that either breaks the molecule apart or allows it to bond with another substrate Once the reaction is complete the enzyme releases the products.
Summarize what is happening in the video clip . . .
Enzymes are Reusable An enzyme only bonds with the substrate it works on for a short time. After the reaction is over, the enzyme returns to it’s original shape and is ready to work again. A single enzyme can induce millions of reactions per second.
Enzyme Naming Enzymes are specific to only one substrate. Since each enzymes only works on one reaction, they are named for the molecules they affect. To name an enzyme, simply add the ~ase ending. Examples Lactose sugar is broken down by the enzyme Lactase Sucrose is digested by the enzyme ______________
Factors that slow enzymes Enzymes are only effective when their active site is in the proper shape. Since enzymes are proteins, they can become denatured (unfolded) and will no longer work. 2 things will denature proteins Changes in pH Changes in Temperature
Activation Energy Many chemical reactions need energy to begin. This energy that starts a reaction is called the activation energy. Examples: Photosynthesis requires activation energy from the sun Wood will not start burning without initial heat source
Activation Energy Video Clip
Enzymes Lower Activation energy Enzymes speed reactions up by reducing the amount of activation energy a reaction needs. The activation energy is reduced because the molecules at the active site are held in positions that make reactions easier.