1. Chemical Reactions in Cells To keep your body alive, your cells undergo countless chemical reactions. – Many of these reactions are occurring 24/7. These chemical reactions drive cellular processes!

2. Cells in your body produce CO 2, then blood carries the CO 2 from the cells to your lungs (you exhale it out). PROBLEM CO 2 is not soluble (dissolvable) in water, so it cannot be carried through your blood. A chemical reaction in your body converts CO 2 into a soluble compound.

3. In blood, CO 2 is converted to a soluble compound: CO 2 + H 2 O  H 2 CO 3 In the lungs, the reaction is reversed to exhale the CO 2 : H 2 CO 3  CO 2 + H 2 O

4. Chemical Reactions & Enzymes

5. Chemical Reactions A change of one set of chemicals into another – Can be slow or fast – Require collisions between molecules – Involves changes in chemical bonds

6. Chemical Reactions Reactants: elements or compounds that enter into a chemical reaction – Bonds of reactants are broken in a chemical reaction. Products: elements or compounds that are produced in a chemical reaction – Bonds of products are formed in a chemical reaction. What are the reactants in this reaction? The products?

7. Chemical reactions involve changes in chemical bonds! Whenever a reaction occurs that rearranges the atoms of molecules, bonds in the reactants must be broken & new bonds in the products must be formed.

8. Chemical Reactions & Energy Breaking & forming chemical bonds requires energy release or absorption. Reactions that release energy can occur spontaneously (but not all do). – Energy is released as heat. Reactions that absorb energy will not occur without an energy source.

9. The chemical reaction of photosynthesis requires energy from the sun.

10. Activation Energy The energy needed to get a reaction started BUT, some chemical reactions are very slow or require lots of energy, so they cannot occur on their own. Activation Energy Video

11. Catalysts Catalysts are proteins that speed up the rate of a chemical reaction by lowering the activation energy of the reaction.

12. Enzymes An enzyme is a protein that acts as a biological catalyst. – Enzymes speed up reactions that take place in your body.

13. Enzymes Enzymes provide a site (called the active site) where reactants (substrate) can be brought together to react. – This decreases the activation energy.

14. Enzymes The structure formed when the substrate (reactants) bind to the active site is called the enzyme-substrate complex.

15. Enzymes Enzymes can be reused, but they are specific. – The enzyme’s structure allows only certain substrates to bind to the enzyme.

16. The enzyme-substrate relationship is like a lock & key! Only the correctly shaped key will open the lock…

20. Enzymes If enough substrate is present, a single enzyme can act on 1,000 molecules per second!

22. Disruptions in homeostasis can prevent enzymes from functioning. Enzymes function best in a small range of conditions. In the wrong conditions, an enzyme can denature (lose its structure). – Temperature changes – pH changes – Other chemicals

23. Why is the shape of the enzyme important?

25. The sugar found in milk is called LACTOSE. Lactose is a disaccharide. This means that lactose is composed of 2 monosaccharides – glucose & galactose. Remember! When you digest your food, your body breaks it up into its smallest subunits.

26. Do we need the enzyme LACTASE to digest milk?