1. The Chemistry of Biology
What does chemistry
have to do with biology?

2. Laws of chemistry -govern the structure & function of all living things.
All organisms are
made of matter –
In living things matter is constantly being rearranged through changes called
chemical reactions
EXAMPLE of a chemical in the body:
This crystal is uric acid, normally found in urine. It displays double refraction under a microscope with polarized light.

3. Everything in the universe is made of matter!
Matter- anything that occupies space and has mass.
Mass- the quantity of matter in an object
-the total number of sub-atomic particles (electrons, protons and neutrons) in the object.
**The chemical properties of matter depend on its organization at the following levels:
Subatomic Atomic Molecular

4. A. The Subatomic level (inside the atom)
Inside the Nucleus:
Proton- positively
charged particle
2. Neutron- neutral,
no electrical charge
Outside the nucleus
3. Electron –small,
negatively charged particles
The Total electrical charge of atom is zero

5. * Atoms are composed mostly of empty space - between nucleus and the orbiting electrons
high energy particles with very little mass.
move around outside the nucleus at very high speeds in areas called orbitals.
An orbital- is a region around the nucleus that indicates the probable location of an electron.

6. Isotopes
All atoms of an element have the same
# of protons.
All atoms of an element do not necessarily have the same # of neutrons.
Isotopes are atoms of the same element with a different # of neutrons.
The additional neutrons change the mass of the atom.
Most elements are a mixture of isotopes.

8. Atomic level- atoms of each element
Element -A substance
that cannot be broken down
by chemical means. Elements
are defined by their number
of protons (Atomic Number)
Example- an atom of Hydrogen,
(H -1)Oxygen (O -8), Carbon (C-6)
*The number of electrons in the outer most energy level determine bonding properties

9. Elements in Living things-
Approx. 25 elements occur in living things.
6 elements of critical importance:
Carbon – Hydrogen – Nitrogen
– Oxygen – Phosphorous - Sulfur
“CHNOPS”
These are found in the 4 major groups of ORGANIC molecules:
Carbohydrates - Lipids
Proteins -Nucleic Acids

10. In the Human Body Note the amounts of “CHNOPS” plus Ca

11. The Periodic table

12. Groups or “Families” vertical columns in the periodic table
these elements share characteristics & traits
groups have similar configurations of the outermost electron shells of their atoms.
Example: Group 14 is the carbon group- Each of the elements in this group has 4 electrons in its outer energy level.
That leaves 4 empty spots for additional electrons- so they form 4 chemical bonds

13. C. Molecular level
Compound- a pure substance made up of atoms of two or more elements
**Most elements undergo chemical reactions- combine in ways that arrange their atoms so the outer electron shell is full & stable
**Compounds have specific formulas
Molecule- the simplest part of a
substance that retains all of the
properties of the substance and
can exist in a free state

14. 2. Chemical bonds
–atoms want to form stable molecules
- Covalent Bonds – some elements are more stable when sharing electrons
- Ionic Bonds- some elements really want to lose or gain an electron- forming cation (+) or anions (-)

15. Covalent Bonds
Formed when 2 or more atoms share one or more pairs of electrons

16. Forming ions

17. Ionic Bonds
Form when a positively and a negatively charged particle called IONS attract each other
These positive and negative IONS form when an atom loses or gains an electron to become “stable” and have a complete # of electrons in the outer shell Example- LiF

18. Energy transfer in Living Things
Definition of Energy- the ability to do work or cause change
Free Energy –the energy in a system that is available for work
For example, in the cell, it is the amount of energy available to fuel cell processes.
Energy can be converted- breakfast food (chemical E) -to thermal E & mechanical E

19. C. Chemical Reactions -many complex chemical reactions occur in living things every second
Reactant: substances that enter a chemical reaction
Product: substances produced by chemical reactions

20. Example: Chemical reaction in body
Reactants & Products
CO2 + H20 == H2CO3
Reactants Products
Reaction is reversible-
shows the
reaction of water and
carbon dioxide to
carbonic acid in blood

21. Photosynthesis: Cellular metabolism:
Which are the reactants & which are products in each reaction. Is this reaction reversible? Explain.
Photosynthesis:
6CO2 + 6H2O + Energy (sun) C6H12O6 + 6O2
Cellular metabolism:
C6H12O6 + 6O2  6CO2 + 6H2O + Energy (ATP)

22. D. Energy for reactions
1. Activation Energy- The amount of energy needed to start a chemical reaction
Catalysts & Enzymes – chemical substances which are able to lower the amount of activation energy needed for a reaction.
Enzymes- are biological catalysts- they lower the activation Energy needed for chemical reactions in living things.
Why are enzymes so important?

23. Features of a catalyzed reaction
Lower activation E needed for reaction w/ catalyst

24. Enzymes and chemical reactions in the body
Lactase is one of many hard working enzymes. It breaks up the chemical bond holding the sugar lactose together.
What happens if you don’t have enough of this enzyme in your body?