1. The Chemistry of Life
Unit One
Biology Notes

2. The Atom Atom – smallest particle of an element
Composed of 3 subatomic particles:
1. Proton – positively charged particle found within the nucleus 2. Neutron – particle with no charge found within the nucleus 3. Electron – negatively charged particle found outside the nucleus

3. Elements Element – pure substance made of one type of atom
Periodic Table – Organizes elements
Atomic Number - # of protons
Atomic Mass - # of protons + neutrons

4. Compounds
Compound – a substance that is made of atoms of different elements chemically combined.
Water is a compound H2O
Properties are different from those of the individual elements.
Table salt (NaCl) – which is made of Na and Cl

5. Compounds

6. Chemical Bonds An atom is most stable when outer most shell is full
Atoms will gain, lose, or share electrons with other atoms to become stable
Valence electrons – electrons in the outermost energy level which are involved in bonding.

7. Bond Types Ionic Bond – electrons are gained or lost
Ion – an atom that has gained or lost electrons
Covalent Bond – sharing electrons
Molecule – a group of atoms held by covalent bonds and have no charge
A molecule of water is represented by H2O

8. Ionic Bond

9. Covalent Bond

10. The Water Molecule
Water is one of the most important compounds in living organisms.
Water serves as a means of transport.
Water makes up 70 – 95% of organisms
Water is an example of a polar molecule
Polar molecule – molecule with an unequal distribution of charge.
Has positive and negative ends = dissolve things
Hydrogen Bond – weak bond between hydrogen and oxygen

11. Hydrogen Bond

12. Solutions and Mixtures
Mixture – a combination of substances in which individual substances retain own properties
Ex. Mix sand and sugar – they neither change nor combine
Solution – a mixture in which one or more substances are distributed evenly in another substance – Ex. Kool-aid mix and water
Solute – substance being dissolved – sugar
Solvent – being dissolved in – Water is the universal solvent

13. Solute vs. Solvent

14. Solution
Na+
Cl -
Water

15. Carbon Compounds Carbon – a very unique and important element
It can share bonds with other carbon atoms or other elements
Can form single, double, or triple bonds
Can form chains, rings, and large complex molecules

16. Macromolecules
Large molecules (polymers) formed by linking many smaller molecules (monomers)
Main categories of macromolecules:
1. Carbohydrates
2. Lipids
3. Nucleic Acids
4. Proteins

17. Carbohydrates
Carbohydrates – organic compounds composed of carbon, hydrogen, and oxygen. Main source of energy for almost all living things
A. Monosaccharides – simplest type of carbohydrate – glucose and fructose
B. Disaccharide – two monosaccharides linked together – sucrose or table sugar
C. Polysaccharide – many monosaccharides (starch, cellulose, and glycogen)

18. Lipids
Lipids – fats used to store energy. Insoluble in water (important to membranes)

19. Nucleic Acids Contain C, H, O, N, and P Store information
Made up of monomers called nucleotides
- RNA – ribonucleic acids
- DNA – deoxyribonucleic acids

20. Nucleotides

21. Proteins Proteins – contain C, H, O, N.
Made of monomers called amino acids.

22. Chemical Reactions
Reactants – substances undergoing the reaction. On left side of arrow
Products – substances being produced. On right side of arrow
Equations – must always be written balanced
H2 + O H2O

23. Enzymes
Catalyst – any substance that speeds up a chemical reaction without being used up in the process. Lowers the activation energy
Enzyme – a protein that acts as a catalyst in a living organism. Changes in temperature or pH can adversely affect enzymes
Substrate – substance that is acted on by the enzyme. It binds to enzyme where a new product is formed and released