Enzyme o/a lets see what you can remember  1. In 30 seconds, tell me 3 things you can remember about enzymes (they are proteins, they catalyze reactions, they are specific, they can be used over and over, they lower activation energy) 2. sketch an enzyme , an active site, and a substrate and label all.

O/A review on enzymes continued true or false? 3. Enzymes make chemical reactions occur…. (false-they lower activation energy to make the reaction quicker/easier) 4. There are only a few type of enzymes in our bodies. (false- since enzymes are specific, there are hundreds to thousands of them in our bodies) 5. Enzymes names are hard to understand. (false- they are usually named be the substrate they act upon and usually end in …..ASE ex. Lipid-lipase, lactose-lactase 6. enzymes can only be used once, then they are broken down and reabsorbed. (false- a single enzyme molecule can catalyze numerous reactions)

A Review of Enzymes and Chemical Reactions

Chemical Reactions: Chemical Reaction: Reactants: Products: A process that changes one set of chemicals into another set of chemicals Reactants: Elements entered into the reaction Products: Elements or Compounds produced by the reaction Always involves the breaking of bonds in reactants and forming of new bonds in products. REACTANTS PRODUCTS

Carbon Dioxide in your Blood: EXAMPLE: Carbon dioxide plus water produces a soluble compound called carbonic acid and is carried through the blood CO2 + H2O H2CO3 In the lungs the reaction is reversed H2CO3 CO2 + H2O

Energy in Reactions: Energy is either released or stored in chemical reactions…Why? Because bonds are formed or broken! Exothermic reactions Reactions that release energy Often occur spontaneously Endothermic reactions Absorb energy Will not occur without a source of energy 2H2 + O2 2H2O

Enzymes: Proteins that act as biological catalysts. Catalyst: Enzymes: A substance that speeds up the rate of chemical reactions. It lowers the activation energy required for the reaction to occur. Enzymes: Proteins that act as biological catalysts. Cells use enzymes to speed up chemical reactions that take place in the cell.

Lock and Key Model When you go home at night and the door is locked, can it open itself or can you use a different key Of course NOT! Enzymes work in the same way. Enzymes complete very specific jobs and do nothing else. Enzymes are the specific locks The compounds they work with are the keys!

Enzyme Action: For a chemical reaction to take place, the reactants must collide with enough energy so that the existing bonds will be broken and new bonds will be formed.

Enzyme-Substrate Complex: Enzymes provide a specific binding site where reactants can be brought together to react. The reactants are known as substrates. Substrate Enzyme

The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form. The active sites are the key holes! The substrates are the keys!

Regulation of Enzyme Activity: Enzymes can be affected by: 1. pH – can change enzymes’ shape 2. Temperature- can change enzymes’ shape and cause them not to work 3. Activators – make enzymes work faster 4. Inhibitors – slow down or stop activity

More Enzyme Facts Each type of enzyme catalyzes only ONE type of reaction Each enzyme can catalyze thousands of the same reaction every minute!

Naming Enzymes The first part of the name comes from the substrate that the enzyme binds with. Always ends in –ASE!!! Example: Substrate = sucrose Enzyme’s Name=sucrase

How do enzymes work? 1. Enzyme and a substrate are in the same area 2. The enzyme grabs onto the substrate with the active site 3. Catalysis occurs – when the substrate is changed into something new. 4. The enzyme lets go and returns to normal – the substrate is no longer the same. The substrate is now called the product