Biology
Scientific Method
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Observation
Question
Hypothesis- educated guess that can be
tested
Experiment-needs to be controlled only
manipulating one variable
Record and analyze-be accurate and use
graphs
Conclusion-you gain evidence to support
hypothesis or disprove hypothesis
Biology “study of life”

Where did life come from?
 A mixture of logic and magic
 Biosphere
○ The part of the earth in which organisms live
○ Land, water, and air

Aristotle (300 BC) and ether
 Spontaneous Generation
Spontaneous Generation
“Recipes”
Bees
Flies
Mice
Geese
Salamanders
Dead Bull in Shed
Rotting Meat
Discarded Rages
Mudding River Banks
Wood & Fire
Francesco Redi’s Experiment
1668 in Italy
 Used cloth cover jars that would not
allow maggots to get to meat
 Proved flies don’t come from rotting
meat
 After hundreds of years of debate,
biogenesis theory replaced spontaneous
generation ideas

Biogenesis- “life comes from life”
Five Properties of Life
1. Organization
2. Energy (metabolism)
3. Growth & Development
4. Reproduction
5. Response & Adaptation
Organization
Atoms
Molecules
Cells
Tissue
Organs
Organ system
Individual
Population
Communities
Ecosystem
Matter, Mass, and Weight
1.
Matter: An object occupies space and
has mass.
2.
Mass: The quantity of matter an object
has.
3.
Weight: The pull of gravity on an
object’s total mass.
Atomic Theory
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All elements are composed of tiny, indivisible
particles that we call atoms.
Atoms of the same element are identical while
atoms of different elements are different.
Atoms can combine together in whole number
ratios.
Atoms can be rearranged into different chemical
compounds by chemical reactions.
Atoms of one element can NOT be changed into
atoms of different elements.
Atoms
Atom:
The smallest unit into
which an element can be
divided and retain its
characteristic properties.
One unit of an element.
Elements
Element: A substance composed only of
atoms of the same atomic
number.
One of more than 100 distinct
types of matter that, singly or in
combination, compose all
materials of the universe.
Atoms: Basic structure
Made up of:
Protons (+)
Neutrons ( )
(Nucleus)
Electrons (-)
Electrically Neutral
if…
Protons =
Electrons
Atomic Number, Symbol, Mass

Atomic Number:
The number of protons
found in an atom.

Symbol: The abbreviation for an element.

Atomic Mass: Weight of an atom; approx.
the sum of its protons and
neutrons.
Periodic Table of the Elements
Beryllium
Atomic Number: 4
Symbol: Be
Name
Atomic Mass: 9.0112
.
4
Be
Beryllium
9.0112
Periodic Table of the Elements
4
Be
Beryllium
9.0112
9
Be
4
Mass = Protons +
Neutrons
What’s wrong with this
picture?
Elements are arranged:
Vertically into Groups
Horizontally Into
Periods
If you looked at one atom
of every element in a
group you would see…
The group 2 atoms all have 2 electrons in their
outer shells
Be (Beryllium)
Atom
Mg (Magnesium) Atom

The number of outer or “valence” electrons in
an atom effects the way an atom bonds.

The way an atom bonds determines many
properties of the element.

This is why elements within a group usually
have similar properties.
If you looked at an atom from each element in
a period
you would see…
Each atom has the same number of electron
holding shells.
An example…
The period 4 atoms each have 4 electron containing
shells
4th Shell
K (Potassium)
Kr (Krypton)
Atom
Atom
Fe (Iron) Atom
Isotopes
Neutrons do not equal protons.
2. More neutrons than protons.
3. Unstable nucleus.
4. Radioactive Isotope: Isotopes that give off
energy because neutrons peel off their
unstable nucleus.
1.
Ions

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

Protons do not equal
electrons.
More protons than
electrons = a positive
charge.
More electrons than
protons = a negative
charge.
+
Na
Compounds
Definition:
 Two or more elements in definite
proportions that are joined together by a
chemical bond.
Two Types of Bonds:
○ Ionic
○ Covalent
Ionic Bonds

Why do they form?

Octet Rule (Rule of Eight):
Atoms tend to establish completely full
outer energy levels. (K fills with 2, L and
M generally fill with 8.)
Ionic Bonds: an example
Chlorine has 17 electrons.
Orbital K takes the first 2.
Orbital L takes the next 8.
Orbital M takes 7.
Sodium has 11 electrons.
Orbital K takes the first 2.
Orbital L takes the next 8.
Orbital M takes 1.
Ionic Bonds: an example
Chlorine needs one more
electron to fill its outer
shell with 8 electrons.
(Octet Rule)
If sodium gives up one
electron it will have
eight in its outer level.
Ionic Bonds: an example
Chlorine:
17 protons
18 electrons
What’s its charge?
-1 (negative ion)
Sodium:
11 protons
10 electrons
What’s its charge?
+1 (positive ion)
What do you
think happens
next?
Ionic Bonds: opposites
attract
The sodium atom and the
chloride atoms are
attracted toward one
another because of their
opposite electrical
charges.
The combination makes sodiumchloride,
abbreviated NaCl,
commonly known as salt.
Ionic Bonds

Definition:
An attraction between ions of opposite
charge.

These bonds are relatively weak and will
easily dissolve in water.
Covalent Bonds
Definition:
A chemical bond formed by the sharing
of one or more pairs of electrons.
 These bonds can be very strong.
 Most of the structures in the body are
made using these types of bonds.
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Molecules

Definition:
A group of elements
held together by
covalent bonds.

Example:
Water
Two hydrogens and
one oxygen share two
pairs of electrons.
Covalent Bonds, cont.

Why do hydrogen and
oxygen want to share?

Answer:
Each wants to fill its
outer shell with
electrons.
Hydrogen fills with 2.
Oxygen fills with 8.
Covalent Bonds
Many types of covalent bonds
Single covalent:
shares one
pair.
Triple covalent:
share three
pairs.
Double
covalent:
share two
pairs.
Chemical Reactions

Equation:
A formula that describes what happens during a
chemical reaction.
H + O
•
2
2
Balanced Equation:
H2O + O
The elements on the left side of the
equation are the same as those on the right.
Notice! States of matter (liquid, solid, gas)
may change during a reaction.
Chemical Reactions: Terms

Activation Energy (Energy of Activation):
The energy needed to make a reaction
occur.
• Reactant- The chemicals before
reaction
• Product- The chemicals after reaction
Water
The Cradle of Life:
1. The Universal Solvent.
2. The Polarity of Water.
Solutions
Solution: A homogeneous mixture of the
molecules of two or more
substances.
Ex. Water and glucose mixture.
Solvent
Solvent:
Medium in which a substance is
dissolved (water).
Water is known as the universal solvent
because most of the chemical reactions
necessary for life take place in water (i.e.
water is the solvent).
Solutes
Solutes:
A compound dissolved in some
solution.
Ex. The glucose in the water
glucose mixture.
Polarity
For example:
 In a water molecule,
one oxygen atom
shares electrons
with two hydrogen
atoms.
Do they share equally?
Polarity, cont.
 Oxygen and
Hydrogen do not
share electrons
equally.
 Oxygen is more
electronegative (it
attracts electrons
more heavily) than
hydrogen.
Polarity, cont.

The result is that the electrons shared by oxygen
and hydrogen actually spend more of their time
nearer the oxygen atom. This gives the oxygen a
slightly negative charge and leaves hydrogen with
a slightly positive charge.
+
-
Note: The charges are only
partial. (i.e. not as large as a full
proton or electron would be.
The Polarity of Water
1.
2.
3.
4.
Water bonds (hydrogen bonds) to
itself.
Water bonds to other molecules.
Water will group non-polar molecules.
Water is a powerful solvent.
Hydrogen Bonds
1.
2.
3.
The positive or negative end of water will
be attracted to other polar molecules.
Weak bonds
Usually last only 1/100,000,000,000 sec.,
but their cumulative effect can be great.
Water Clings
Cohesion: Water attracted to water.
Adhesion: Water attracted to other polar
molecules.
Capillary Action – water will “climb” by
adhering to a surfaces electrical charges.
Adhesion
Hydrophobic:
Water-fearing
Water tends to form hydrogen bonds. When
it mixes with non-polar molecules, it tends to
shun them and instead cling to other water
molecules.
Hydrophilic:
Water-loving.
Polar compounds will form hydrogen bonds
with water. This breaks ionic bonds,
dissolving the compound.
It’s reactions…
Acids and Bases
pH
1.
2.
3.
4.
A measure of the relative concentration
of hydrogen ions in a solution.
Values range from 0 to 14.
Less than 7 is an acid.
More than 7 is a base.
Acids
1.
2.
3.
A substance that causes an increase in
the concentration of H+ ions.
Tastes sour.
Tingles the skin.
Bases
1.
2.
3.
4.
A substance that causes a decrease in
the relative concentration of H+ ions.
Also called alkaline.
Tastes bitter.
Sometimes slippery or slick feeling.
Chemical Reactions
Catalyst-substance that speed up
chemical reaction
 Enzyme-is a protein that acts as a
biological catalyst

Elements important for life.
Oxygen (65% of body by weight)
 Carbon (18%)
 Hydrogen (10%)
 Nitrogen (3%)

(N.O.C.H.)
Elements in Human Body
Oxygen (65%)
 Carbon (18%)
 Hydrogen (10%)
 Nitrogen (3%)
 Calcium (2%)
 Phosphorus
(1%)

Other 1%
 Potassium
 Silicon
 Aluminum
 Iron
 Sodium
 Chlorine
 more...
Organic Compounds
1.
Pertaining to living things.
2.
The chemistry of compounds containing
carbon.
Building Macromolecules
Monomer-smaller unit of large
compounds
 Polymers-monomer that join together to
form macromolecules

Organic Compounds or
Macromolecules
4 Types of Organic Compounds:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids.
Carbohydrates
Three types:
1. Monosaccharides
2. Disaccharides
3. Polysaccharides
Monosaccharides
One sugar molecule.
Carbon Backbone: Carbon atoms line up
near the center of the molecule and other
atoms attach to them.
Formula for Simple Sugars: C6H12O6
Monosaccharides
Three basic types:
1. Glucose (general sugar)
2. Fructose (fruits)
3. Galactose (milk)
Isomer:
that
Alternative forms of a molecule
have the same formula.
Polysaccharides
Many monosaccharides bonded together.
(Storage sugars.)
Three types:
1. Starches (plants – potato!).
2. Cellulose (structure – plant cell walls).
3. Glycogen (animal storage).
Functions of Carbohydrates
1.
2.
3.
Energy source (glucose).
Long-term energy storage (starch,
glycogen).
Structure (cellulose).
Organic Compounds
4 Types of Organic Compounds:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids.
Lipids
Five types:
1. Fats
2. Oils
3. Waxes
4. Phospholipids
5. Steroids
Lipids
Functions:
 Long-term energy storage (fats, oils).
 Insulation (fat).
 Protection (waxes waterproof or keep in
water).
 Cell membrane structure (phospholipids).
 Control of body functions (steroids).
Organic Compounds
4 Types of Organic Compounds:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids.
Proteins
Types:
1. Amino acids.
2. Dipeptides.
3. Polypeptides.
Proteins
Amino Acids:
 Building blocks for all proteins.
 20 total.
 Link together to form “peptide” bonds.
Proteins
Functions:
 Movement
 Structure
 Regulation (catalysts, enzymes)
 Transport
 Nutrition
 Defense
Proteins
(catalysts and enzymes)
Catalyst: Substances used in small amounts
which speed up chemical reactions
without themselves being affected by the
reaction.
Enzyme: Proteins that function as catalysts.
(overhead)
Organic Compounds
4 Types of Organic Compounds:
 Carbohydrates
 Lipids
 Proteins
 Nucleic Acids.
Nucleic Acids
Types:
 DNA (deoxyribonucleic acid)

RNA (ribonucleic acid)
Functions of Nucleic Acids

Information storage (DNA)

Information transfer (RNA carries genetic
information from DNA to ribosomes)