Unit 1 Notes:
Chemistry
All Biology consists of Chemistry
 All
organisms are made up of matter.
Matter is anything that takes up
space and has mass.
 Matter is made up of one or more
chemical elements. An element is a
pure substance that cannot be
broken down into any other
substances.
Elements
 There
are about 25 different elements that are
essential for life
 4 main elements that make up the majority of
living matter are; oxygen, carbon, hydrogen, and
nitrogen.
 These make up 96% of living matter
 And then there are trace elements that are
just as important for your body to function
correctly, but they are found in very small
amounts; iodine, iron.
 Trace elements make up less than 0.01% of
your body!
Compounds
 Compounds
are substances that are made up of
two or more elements. These elements are put
together in specific ratios.
 For example, there are 2 hydrogen's needed
for every oxygen in water (H2O)
 A compounds properties can be very different
for the individual elements that it is made up
of.
 Most compounds are made up of 3 or 4
different elements (C6H12O6)
Atoms
 An
atom is the absolute smallest part of an
element.
 Atoms are made up of:
 Protons which have positive charges
 Electrons which are negatively charged
 Neutrons which are neutral
They give an element its physical and
chemical properties depending on how the
protons, neutrons and electrons are
arranged.
Where are the parts of an atom found?
 In
an atom you find the protons and
neutrons in the nucleus, the electrons
orbit around the nucleus in a “cloud”.
 All atoms of an element have the same
atomic number or protons, it is the
number of neutrons that can change.
Isotopes
 An
isotope is formed when an element has the
same number of protons in the atom but
changes numbers of neutrons in its nucleus.
 ***Adding a proton makes a new kind of atom,
Adding a neutron makes an isotope of that atom
and a heavier version of that atom
 Some elements can have quite a few different
forms because there are several different
numbers of neutrons found in nature.
For example:
Radioactive Isotope
 As
more neutrons are added to the
nucleus, the atom becomes unstable
making the nucleus decay or give off
energy.
 This matter and energy given off is
radiation, which can be damaging, but also
has many medical uses.
 An enriched form of water with an
isotope of oxygen is the basis for PET
scans to detect brain, heart, and
abdominal cancers.
 An
Electrons are important in
chemical bonds!
atoms structure and arrangement of
electrons determines how that atom will
react with another.
 When electron energy levels are not
completely filled, the atoms are
chemically reactive.
 The atoms want to have a filled energy
level, so bonds are formed to make this
happen.
Bonds
There are two types of bonds that we will talk
about:
 1. Ionic bonds-one atom transfers electrons
to another atom
 This transfer makes the atom that has lost
the electron positive and the atom that has
gained the electron more negative
 The two atoms that have changed are know
as ions. A positive ion=cation: A negative
ion=anion.


2. Covalent bonds-two atoms
share electrons. Two or more
atoms held together by covalent
bonds=molecule
Chemical Reactions
 Atoms
are constantly being
rearranged by chemical reactions
which can form new substances.
 This rearrangement can be easily
seen in a chemical equation which
is very much like a math equation.
 The
starting material, or what
goes into the reaction, are the
reactants.
 The ending material, or how the
reactants combine together, is
known as the products.
 It
is important to remember that
chemical reactions do not create
or destroy atoms, they only
rearrange them.
 With this rearrangement there
are new bonds forming and other
bonds breaking.
Elements
are listed on the periodic
table in an order based on number of
protons.
# protons = # electrons
Why aren’t there the same amount of
neutrons too?
 Because of isotopes!
• Different number of neutrons can
change the type of element.
•Element Equations on Periodic Table
*Number of Protons = Atomic Number
*Number of Electrons = Number of Protons
= Atomic Number
*Number of Neutrons = Atomic Mass –
Atomic Number
How

36
How

many electrons?
36
How

many protons?
many neutrons?
84 – 36 = 48
# protons = 42
# electrons = 42
# neutrons:
96 – 42 = 54
The Role of Carbon in Organisms
A carbon
atoms has 4 electrons
available for bonding
Has a great ability to bond with other
atoms
Large carbon compounds (thousands of
carbon atoms) are called biomolecules
 EX: Proteins
Polymer: large molecule formed when
MANY smaller molecules bond together
Carbohydrates
Carbohydrates
give energy to cells.
 Carbo-load before a big race? It really works!
Carbohydrate: biomolecule of carbon, hydrogen, and
oxygen
 EX: Monosaccharide (simple sugar): glucose,
fructose.
 EX: Polysaccharide (many sugars): starch,
glycogen, cellulose
Going on a carb-free diet?
 Your body doesn’t need as many carbs as you give
it on a daily basis because we store carbohydates!
 However, you still need carbs every day, your cells
need their energy to keep you living.
Lipids
Lipids:
large biomolecules made mostly
of carbon and hydrogen with a small
amount of oxygen.
EX: fats, oils, waxes, and steroids.
Don’t think about getting rid of lipids from
your diet just yet!
Cells use lipids for energy storage,
insulation, and protective coverings.
 The major components of cell
membranes are lipids
Proteins
Protein:
large, complex polymer composed
of carbon, hydrogen, oxygen and nitrogen.
Proteins are essential to all life.
 Provide structure for tissues/organs and
carry out everyday cell processes
Amino Acids: basic building blocks of
proteins
About 20 common amino acids that we will
cover in the DNA unit
 Ever hear of tryptophan on Thanksgiving?
Enzymes
Enzyme:
protein that changes the rate of a
chemical reaction.
Enzymes are involved in nearly all
metabolic processes.
 In some cases, enzymes speed up
reactions that otherwise would be slow.
 EX: speed up digestion of food
 Enzyme activity depends on temperature
and pH conditions.