This document provides an introduction to chemistry concepts that form the foundation of biology for an AP Biology class. It discusses the levels of biological organization from atoms to organisms. Atoms are made of protons, neutrons, and electrons. Elements are different types of atoms that can bond through covalent or hydrogen bonds to form molecules like water, which is essential for life. Organic molecules contain carbon and make up biomolecules or macromolecules that are the building blocks of living things, forming from small monomers that polymerize.

1. AP Biology 2007-2008
The
Chemistry of Life

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

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

4. AP Biology
Proton Neutron Electron
Hydrogen
1 proton
1 electron
Oxygen
8 protons
8 neutrons
8 electrons
+ 0 –
 Everything is made of matter
 Matter is made of atoms

5. 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!

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

7. AP Biology
The World of Elements
C
Different kinds of atoms = elements
H
O
N
P S
Na
K
Mg
Ca

8. 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)

9. 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!

10. AP Biology
–
–
H2 (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
H2O
H2O

11. 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

12. 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!

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

14. 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!

15. AP Biology
Chemistry of water
 H2O 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.

16. AP Biology
What are organic molecules?
All organic molecules contain carbon.
Inorganic molecules do NOT contain
carbon (Ex: H2O)
There are three main elements that are
present in all living things:
 CARBON
 OXYGEN
 HYDROGEN

17. 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!

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

19. 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