Linnaeus’ Classification System
1. What is a species?
A. A population of organisms that share similar characteristics and can breed with one another
and produce fertile offspring.
What are some examples of species? Dogs, Cats, Humans, etc.
B. How many species have scientists identified (about 1.5 million) and how many have yet to be
discovered? Between 2 and 100 million
2. Why classify organisms?
A. Biologists must attempt to organize living things into groups that have biological meaning.
B. To study the diversity of life, biologists use a classification system to name organisms and
group them in a logical manner.
C. The study where scientists classify organisms and assign a universally accepted name is called
taxonomy.
D. By using a scientific name, biologists can be certain that everyone is discussing the same
organism.
E. Scientists organize organisms into groups that have biological significance.
 In a good system of classification, organisms placed into a particular group are more
similar to each other than organisms in other groups.
3. Assigning Scientific Names
A. Common names such as cougar, puma, and panther are all referring to the same animal but
vary among languages and even among regions within a single country thus leading to
confusion among different populations of people.
B. A Swedish botanist by the name of Carolus Linnaeus developed a two-word naming system
called binomial nomenclature.
 Each species is assigned a two-part scientific name.
1. The scientific name is always written in italics.
2. The first word is always capitalized and represents the genus of an organism.
3. The second word is always lowercased and is a specific Latin description of each
individual organism.
4. A few examples are: Muntiacus muntjak, Ursus maritimus, and Felis concolor.
Grizzly Bear
Ursus arctos
Polar Bear
Ursus maritimus
Panda Bear
Ailuropoda melanoleuca
Do Ursus arctos and Ursus maritimus belong to the same species? No
To the same genus? Yes
4. Linnaeus’s System of Classification—based on similarities between structural characteristics
A. This classification system is hierarchical which means it consists of levels.
B. There are 7 levels
(most broad down to most specific)
Broad
Specific
1. Kingdom (ex: Animalia)
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
(ex: Chordata)
(ex: Mammalia)
(ex: Carnivora)
(ex: Ursidae)
(ex: Ursus)
(ex: Ursus arctos)
(Hint: King Phillip Came Over For Good Spaghetti!)
Kingdom: the largest and most inclusive of Linnaeus’s taxonomic categories; the broadest description of
an organism.
Phylum:
includes many different organisms that share important characteristics; phyla make up
Kingdoms.
Class:
a group of similar orders; several different classes make up a phylum
Order:
a broad taxonomic category composed of similar families; orders make up each class
Family:
a group of genera that share many characteristics; families make up orders
Genus:
a group of closely related species; the first capitalized word in the two-part naming system
developed by Linnaeus
Species:
a population of organisms that share similar characteristics and can breed with one another
and produce fertile offspring
Note: 2 organisms classified in the same class must also be in the same phylum
and kingdom but does not necessarily have to be in the same order.
VIRUS NOTES
I. VIRUSES
A. General Characteristics:
1. A virus is an infectious agent made up of nucleic acid (DNA or RNA) wrapped in a
protein coat called a capsid.
2. Viruses have no nucleus, no organelles, no cytoplasm or cell membrane – Non-cellular
and Non-Living.
3.Viruses are parasites—an organism that depends entirely upon another living organism (a
host) for its existence in such a way that it harms that organism.
B. Examples:
1. Retroviruses - Viruses have either DNA or RNA but NOT both.
a.Have RNA instead of DNA
b.The genetic material mutates (changes) often.
c. Example: HIV
1. Bacteriophage—viruses that infect bacteria
2. Flu (influenza), HIV
DNA or
RNA
Capsid (protein coat)
– inside contains either
RNA or DNA
Surface Marker
Capsid (protein
coat)
C. Replication (reproduction): is how a virus spreads
A virus CANNOT reproduce by itself – it must invade a host cell and take over the cell
activities, eventually causing destruction of the cell and killing it. (The virus enters a cell,
makes copies of itself and causes the cell to bursts releasing more viruses.)
Cell bursts (lyses)
and releases new
viruses.
Virus (bacteriophage) invading a bacterium (E. coli)
DNA/RNA is copied.
Virus attaches to
cell.
Step
1
Step
2
DNA/RNA
injected into
cell.
Step
3
Step 4
Virus copies
itself.
Step
5
cell.
D. Certain viruses can only attack certain cell types. They are said to be specific.
Example: The rabies virus only attacks brain or nervous cells.
A virus recognizes cells it can infect by matching its surface marker with a receptor site on a
Virus
Surface
Marker
s
Receptor
Sites
Cell
E. Two Different Life Cycles of Viruses
The virus attaches to bacteria
(host)
The virus inserts its DNA into the bacteria
The virus takes over the cell's machinery
The virus reproduces itself and selfassembles. The host cell is destroyed
The virus binds to bacteria (host)
The virus inserts its DNA into the bacteria
The viral DNA gets incorporated into the cell's
chromosome
Viral DNA is replicated along with
chromosomal material
*_______ DISEASE SHOWS UP
*BUT IF THE HOST IS ____________, THE VIRUS CAN
CHANGE FROM THE LYSOGENIC TO LYTIC CYCLE
AND MAKE YOU ______________

F. Importance
1. Viruses can be harmful or
pathogenic. –causing disease
pathogen -disease producing agent –
a. Human diseases –
i.
Flu – fever, cough, sore throat, sinus congestion
ii. HIV – weakens immune system. The HIV virus causes AIDS.
iii. Common cold and warts
b. Viruses disrupt the body’s normal equilibrium/balance
c. Can be prevented with vaccines, but NOT treated/cured with antibiotics (antibiotics
treat bacteria).
2. Viruses can be beneficial:
Genetic Engineering – harmless virus carries good genes into cells.
Characteristic
VIRUS
CELL
Structure
RNA or DNA core,
protein coat (capsid)
cell membrane,
cytoplasm, genetic
material, organelles
Reproduction
No
Copies itself only inside
host cell
Yes
Genetic Code
DNA or RNA
DNA and RNA
Growth and
Development
No
Yes—Multicellular
Organisms
Obtain and use energy
(metabolize food)
No
Yes
Response to
Environment
No
Yes
Change over time
Yes
Yes
* Think back to the 8 characteristics of life: How many
characteristics of life do viruses possess? Two (genetic material –
DNA/RNA and change over time) Then are they living? No
Bacteria Notes
I.
Kingdom Eubacteria (True Bacteria)
Bacteria are located everywhere – air, water, land, and living organisms including people.
A. General Characteristics
1. All are unicellular (one-celled structural level)
2. All are prokaryotic – cells that lack nucleus (no nuclear envelope) (PRO = NO nucleus)
3. All have cell walls – NO cellulose in cell walls
4. Can live in both aerobic (with O2) and anaerobic (without O2) environments
5. Bacteria are much larger in size than viruses.
Genetic Material
Flagella
Cell
Membrane
Cytoplasm
Cell Wall
B. Causes Disease by:
1. Destroying cells of infected organism by breaking the cells down for food.
2. Releases toxins (poisons) which destroy cells of infected organism.
3. Must have access to new hosts to spread.
C. Importance:
1. Beneficial
a. breakdown dead matter to recycle nutrients into ecosystem - decomposers
Example: Compost piles need microorganisms (ex. bacteria) to decompose
(breakdown) matter.
b. dairy industry – bacteria in yogurt, sour cream, and cheese
c. oil spills – bacteria can digest small oil spills
d. genetic engineering – recombinant/synthetic DNA (Ex: Insulin)
e. symbiotic relationship – E. coli and intestines
Example: E. coli in intestines helps us digest food and make vitamins (such as Vitamin
K and B-complex) which our bodies absorb. In return, human intestines
provide food and shelter for the E. coli bacteria.
(This strain of E. coli is different from the E. coli strain that causes food
poisoning.)
2. Harmful
a. Human diseases – strep throat, tuberculosis, tooth decay and bad breath, anthrax,
plague,
tetanus, food poisoning
b. Food spoilage and poisoning – caused by Salmonella and Staphylococcus
c. Treated with antibiotics – A genetic variation may exist in the bacteria population so
some bacteria are able to survive in presence of antibiotics that kill other bacteria—
antibiotic resistant bacteria. These resistant bacteria survive and reproduce until
you have a population of bacteria that are immune to the antibiotic.
Note: This is why doctors tell you to take the entire amount of medicine given even if
you start to feel better because if not, bacteria will have the chance to evolve and
become antibiotic resistant.
II.
Kingdom Archaebacteria
A. First known prokaryotes – Archaebacteria (archae = ancient)
B. Live in very harsh environments (known as extremophiles) – high salt content, hot
temperatures,
acidic or alkaline environements
Example: Hot Springs of Yellowstone National Park and the Dead Sea (high salt content)
C. Live in intestines of animals, especially cows and other grazing animals – methanogens
Example: Produce methane gas – greatly affects our atmosphere by combining with O2 to
make CO2 for photosynthesis.
D. Same size and shape as Eubacteria, but different biochemical make-up.