1. Chapter 2
The Chemistry of Life

2. Section 1 – The Nature of Matter
Atoms are the basic unit of matter.
Subatomic particles that make up atoms are protons, neutrons, and electrons.
Protons – positively charged particles
Neutrons – carry no charge, neutral
Protons and neutrons are found in the nucleus of the atom

3. Electrons Electron – negatively charged particle
In constant motion in the space surrounding the nucleus.

4. Elements
Element – pure substance that consists entirely of one type of atom.
Represented by a one- or two- letter symbol.
Elements are arranged into the periodic table.

5. Chemical Compounds
A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions.

6. Chemical Bonds
Ionic bonds – formed when one or more electrons are transferred from one atom to another.
Covalent bonds – formed when electrons are shared between atoms.
Van der Waals forces – when molecules are close together, a slight attraction can develop between oppositely charged regions of nearby molecules. These attractions are not as strong as ionic or covalent bonds.

7. Section 2 - Properties of Water
Polarity – a molecule in which the charges are unevenly distributed is a polar molecule.
A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.

8. Hydrogen Bonds
A single water molecule may be involved in as many as four hydrogen bonds at the same time.
Cohesion: an attraction between molecules of the same substance.
Adhesion: an attraction between molecules of different substances.

9. Mixture
Mixture – a material composed of two or more elements or compounds that are physically mixed together but not chemically combined.

10. Solutions Solution – all components are evenly distributed throughout.
Solute – the substance that is dissolved
Solvent – the substance in which the solute dissolves

11. Suspensions Suspension – mixture of water and non-dissolved materials.
Materials will separate into pieces but do not settle out

12. Acids, Bases and pH
The pH scale – a measurement system that indicates the concentration of H+ ions in a solution.
Ranges from 1 – 14
7 is neutral
Under 7 is acidic
Above 7 is basic

13. Acids
Any compound that forms H+ ions in solutions.
pH value below 7

14. Bases Any compound that produces hydroxide (OH-) ions.
pH value above 7

15. Buffers
Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.
Help control pH and retain homeostasis in the body.

16. Section 3 – Carbon Compounds
Macromolecule: LARGE carbon molecule
Polymer: Large molecule formed when many smaller molecules bond together

17. Carbohydrates 2 H atoms for every O & C
1. Simplest carbs: Called Monosaccharides (one sugar)
-Ex: glucose; fructose
- 2. Disaccharides – two sugars
-Sucrose (glucose + fructose)
- 3. Polysaccharides – many sugars
-Starch, glycogen, and cellulose

18. Lipids
Lipids: Fats; Organic compounds that have a large proportion of C-H bonds and less O than carbs.  
Insoluble in water because lipids are nonpolar
 Saturated Fat: Animal fats
Unsaturated Fat: Oils

19. Proteins
A large, complex polymer composed of carbon, hydrogen, oxygen, nitrogen, and usually sulfur; have an “R” group that makes each different
Made from amino acids 
20 common amino acids 
Proteins are the building blocks of many structural components

20. Proteins
Amino Acids are linked together when an H-group and –OH group are removed to form water
The covalent bond formed between A.A. is a PEPTIDE BOND

21. Nucleic Acids
A complex macromolecule that stores cellular info. in the form of a code
Nucleic acids are made up of smaller subunits called Nucleotides
Nucleotides consist of three basic parts:
1. Nitrogen-containing base
2. Pentose sugar
3. Phosphate group

22. Types of Nucleic Acids 1. DNA: Deoxyribonucleic acid
Master copy of organism’s genetic info.
Contains instructions used to form organism’s enzymes and proteins
2. RNA: Ribonucleic acid
Forms a copy of DNA for use in making copies and proteins

23. Section 4 - Chemical Reactions
Chemical formulas describe the substances in the reaction and arrows indicate the process of change
Reactants – starting substances on the left side of the arrow
Products – substances formed during the reaction on the right side of arrow
Arrow can be read as “yields” or “react to form”

24. Energy in Reactions Key to starting a chemical reaction is energy
Energy in the form of heat is need
Most compounds in living things cannot undergo chemical reactions without energy

25. Activation Energy
Minimum amount of energy needed for reactants to form products in a chemical reaction

26. Energy Change in Chemical Reactions
In every chemical reaction, there is a change in energy due to the making and breaking of chemical bonds
Exothermic reactions – energy of the product is lower than the energy of the reactants
Energy is released in the form of heat
Endothermic reactions – energy of the products is higher than the energy of the reactant
Heat energy is absorbed

27. Endothermic Reaction

28. Exothermic Reaction

29. Enzymes
Catalyst – substance that lowers the activation energy needed to start a chemical reaction
Enzymes – special proteins that are the biological catalysts that speed up the rate of chemical reactions in biological processes
Essential to life
Not used up by the chemical reaction
Can be used again
Most enzymes are specific to one reaction

30. Enzymes Substrates – reactants that bind to the enzyme
Active Site – specific location where a substrate binds on an enzyme
The active site and substrates have complementary shapes
Only the substrate with the same shape as the active site will bind to the enzyme
Example : Lock & Key

31. Enzymes
Once the substrates bind to the active site, the site changes shape and forms the enzyme-substrate complex
The new complex helps chemical bonds in the reactants to be broken and new bonds are formed
The substrates react to form products
The enzyme then releases the products

32. Enzymes
Factors such as pH, temperature, and other substances affect enzyme activity
Enzymes affect many biological processes
Examples:
Photosynthesis
Respiration
Snake bite
Fruit ripening