2. AP Biology 2007-2008 The Chemistry of Life

3. AP Biology Why are we studying chemistry? Chemistry is the foundation of Biology

4. AP Biology What level of organization are we now on? atom compound cell tissue Organ system organism organ molecule

5. AP Biology ProtonNeutronElectron Hydrogen 1 proton 1 electron Oxygen 8 protons 8 neutrons 8 electrons +0–  Everything is made of matter  Matter is made of atoms

6. AP Biology What are atoms made of?  Each atom is made of protons, neutrons and electrons  Protons are positively charged particles  Neutrons are neutral (they have no charge)  Electrons are negatively charged particles Draw the atom from the board in your notebook !

7. AP Biology Why are electrons important?  two atoms connect to each other through the interaction of the electrons – –

8. AP Biology The World of Elements C Different kinds of atoms = elements H ON PSNa K Mg Ca

9. AP Biology Life requires ~25 chemical elements  About 25 elements are essential for life  Four elements make up 96% of living matter: carbon (C) hydrogen (H) oxygen (O) nitrogen (N)  Four elements make up most of remaining 4%: phosphorus (P) calcium (Ca) sulfur (S) potassium (K)

10. AP Biology What is a compound?  A compound is a substance made up of atoms of two or more different elements. This example is carbon dioxide Molecules are made of atoms. Compounds are types of molecules! Draw the molecule From the board In your notebook !

11. AP Biology – – H 2 (hydrogen gas) Covalent bond Bonds in Biology  Weak bonds  hydrogen bonds  attraction between + and –  Strong bonds  covalent bonds  two atoms share a pair or more of electrons  Both atoms are holding on  Very stable and forms MOLECULES!  More than one pair of elections = double and triple bonds… VERY STRONG!  CARBON forms ORGANIC MOLECULES Hydrogen bond H2OH2O H2OH2O

12. AP Biology What is an example of Hydrogen bonding in biology?  A hydrogen bond is a weak chemical bond. * The strands of DNA are bonded by hydrogen bonds

13. AP Biology Why do we need to know about BONDS??  Think back to levels of organization: when we start with an atom and go to a compound what is happening in between the arrows?  To go from an atom to an organism, bonding must occur! For example, BONDS form molecules from atoms… like WATER! Illustrate the bonds from The board in your notebook!

14. AP Biology WATER IS A MOLECULE! All life occurs in water  inside & outside the cell All life occurs in water  inside & outside the cell

15. AP Biology Water makes up the environment AND a large part of the mass of most organisms is water!  In human tissues, the percentage of water ranges from 20% in bones to 85% in brain cells!  The water content is greatest in young cells and decreases with age.  About 70% of your total body weight is water and about 95% of jellyfish and some plants is water! Water, water, water!

16. AP Biology Chemistry of water  H 2 O molecules form H-bonds with each other (hydrogen)  +H attracted to –O  creates a sticky molecule  The charges cause water to ionize at times, making H+ (acidic) and OH- (basic) which is important in measuring pH of something.

17. AP Biology What are organic molecules? All organic molecules contain carbon. Inorganic molecules do NOT contain carbon (Ex: H 2 O) There are three main elements that are present in all living things: CARBON OXYGEN HYDROGEN

18. AP Biology What are biomolecules? Large Organic molecules that exist in all living things Also known as Macromolecules (Macro=Large) They are life's building blocks All living things are formed from these molecules Draw the macromolecule From the board In your notebook!

19. AP Biology Biomolecules are complex, but are made up of simpler components

20. AP Biology Biomolecules cont…. Biomolecules start out small as monomers and you add on to them to build them up to become polymers SMALL TO BIG Mono= One Poly= Many