1. The Chemistry of Life Ch

2. Recall: Levels of Organization

3. Biology Depends on Chemistry
In our biosphere, everything is made of atoms
Through the interaction of chemicals we can better understand our biosphere

4. Atoms Basic unit of matter Protons Neutrons Electrons (+) charge
In nucleus
Neutrons
(0) charge
Electrons
(-) charge
Around nucleus at varying energy levels

5. Molecules 2 or more atoms held together by chemical bonds
Importance to biology: macromolecules make up cells and cellular components

6. Chemical Bonds: Ionic Electrons transferred from one atom to another
Ex: NaCl (salt)
Importance to biology: many salts are made this way (homeostatic balance)

7. Chemical Bonds: Covalent
Electrons are shared between atoms
Ex: CO2
Importance to biology: carbon compounds, water

8. Chemical Bonds: Hydrogen
Weak bond formed from by the attraction of two electronegative molecules
Slightly positive, slightly negative ends
Importance to biology: critical to water’s properties, holds DNA together

9. Chemical Reactions Synthesis Decomposition
Make a compound
Ex: Photosynthesis
Decomposition
Break down a compound
Ex: Cellular Respiration
Both reactions important to biology: metabolism