Number 1 What is a chemical reaction?

Transcription

1 Chemical Reactions and Enzymes

2 Number 1 What is a chemical reaction? A process that changes, or transforms, one set of chemicals into another by changing the chemical bonds that join atoms in compounds.

3 Number 2 What is conserved during chemical transformations? MASS ENERGY

4 Number 3 Compare / contrast reactants and products. Both are parts of a chemical reaction and both can be elements or compounds Reactants are the elements or compounds that enter into a chemical reaction Products are the elements or compounds produced by a chemical reaction

5 Number 4 Reactants and products of the following 2 Na + 2 HCl 2 NaCl + H 2 REACTANTS PRODUCTS

6 Number 5 What is changed in a chemical reaction? The chemical bonds that join atoms in compounds are changed in a chemical reaction Bonds can be either created or broken

7 Number 6 Why is the melting of ice not a chemical reaction? New chemical bonds are not formed The bonds between hydrogen and oxygen are not changed

8 Number 7 Chemical reaction in your bloodstream As CO 2 enters the blood, it reacts with water to produce carbonic acid (H 2 CO 3 ), which is highly soluble This reaction enables the blood to carry the carbon dioxide to the lungs In the lungs, the reaction is reversed and produces carbon dioxide gas, which you exhale

9 Number 8 How do plants get the energy needed to stay alive? Plants trap and store the energy from sunlight in energy-rich compounds

10 Number 9 How do animals get the energy needed to stay alive? Animals consume plants or other animals to get their energy

11 Number 10 What is activation energy? The energy that is needed to get a reaction started It is the difference between the required energy and the energy of the reactants

12 Number 11 Label the following C A B A = Reactants B = Activation Energy C = Products This is an energy-absorbing reaction (endothermic reaction)

13 Number 11 Label the following A B C A = Reactants B = Activation Energy C = Products This is an energy-releasing reaction (exothermic)

14 Number 12 What is a catalyst? Why are catalysts important? A substance that speeds up the rate of a chemical reaction Catalysts work by lowering the activation energy Catalysts are important because some reactions that make life possible are too slow or have activation energies that are too high

15 Number 13 What are enzymes? Proteins that act as biological catalysts Enzymes speed up chemical reactions that take place in cells

16 Number 14 Steps of an enzyme-catalyzed reaction 1. The substrates bind to the enzyme on the active site 2. The substrates are converted into products 3. The products are released 4. The enyzme is ready for another reaction The enzyme brings the substrate together which means less energy is required

17 Number 15 Why is the enzyme-substrate complex compared to a lock and key? The active site and the substrates have complementary shapes The fit is very precise, much like a lock that can only be The fit is very precise, much like a lock that can only be opened by one key

18 Number 16 What are some variables that can affect enzymes? Temperature, ph, and regulatory molecules are all factors that can affect the activity of enzymes. Enzymes work best at certain temperatures. Enzymes produced by human cells generally work best at temperatures close to 37 degrees Celcius, 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.