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Taxonomy
SBI 3C
Definition: ________________________ is the science of classifying organisms (both living & extinct).
Taxonomic System
 developed by Carl Linnaeus (1707-1778) in ___________________
 based his classification on ____________________ and ______________________ features
 the ____________ features organisms have in common, the __________________ their relationship
Binomial Nomenclature (common worldwide language)
 The ________________________ Name:
note: both parts of the scientific name
first part of name – called the __________________
 first letter is always _____________________
are italicized
 this part __________ be written ____________ (e.x. Acer meaning all maple trees, Ursus = all bears)
second part of name – called the ________________
 is __________ capitalized (lowercase)
 is ______________ written ___________________ (e.x. Acer rubrum, referring to a red maple, Ursus
americanus = North American Black Bears)
Species
species: a _____________ of organisms with similar features that can interbreed and produce fertile offspring
horse
+
donkey
=
Binomial Nomenclature
Genus
Homo
Castor
Escherichia
Species
sapiens
canadensis
coli
7 Levels of Classification
 ______________________
 ______________________
 ______________________
 ______________________
 ______________________
 ______________________
 ______________________
Abbreviated
H. sapiens
C. Canadensis
E. coli
Common Name
human
beaver
E. coli
Largest / General
Smallest / Specific
mule
Taxonomic Classifications
Man
Gorilla
Chimpanzee
Orangutan
Baboon
Kingdom
Animalia
Animalia
Animalia
Animalia
Animalia
Phyllum
Chordata
Chordata
Chordata
Chordata
Chordata
Class
Mammalia
Mammalia
Mammalia
Mammalia
Mammalia
Order
Primates
Primates
Primates
Primates
Primates
Family
Hominidae
Hominidae
Hominidae
Hominidae
Hominidae
Subfamily
Homininae
Homininae
Homininae
Ponginae
Cercopithecidae
Genus
Homo
Gorilla
Pan
Pongo
Papio
Species
sapiens
gorilla
troglodytes
pygmaeus
ursinus
Gorillas & Chimps have __________% same DNA as us.
Dichotomous Key
 _________-part key used to identify ______________ things
 a series of ___________________ must be made
 each choice leads to a new __________________ of the key
 end result is the _________________ of the organism being identified
Complete Activity 2.2 on page 102. We will also look at a few other classification keys.
 Homework: Text
 Page 101 # 1 – 7
Microbiology
Microbiology is the field of biology that studies microorganisms such as:
•
viruses • archaea • eubacteria • protists • fungi
Microorganisms are either:
1. prokaryotic – cells which have no nucleus and no membrane-bound organelles (archaea and
eubacteria, the two types of bacteria)
1. eukaryotic – cells which have numerous membrane-bound organelles including a nucleus (protists,
fungi, plants, animals)
Microorganisms usually require magnification to be observed. Many are unicellular (made of a single cell) and
others form multicellular groups of associated cells.
6 Kingdom Classification System
1.
2.
3.
4.
5.
6.
The 5 Kingdoms
Archaebacteria / Eubacteria
Viruses
Questions
1. Where do viruses fit into the model of the 6 Kingdom classification system?
2. Are viruses considered living organisms?
Viruses
What are the characteristics of living organisms?
 Living things…
are made of cells
grow and develop
reproduce
respond to their environment
adapt to their environment
obtain and use energy
produce wastes
… unless they are reproducing
Answer
 viruses are not considered to be living organisms because:
1. not made up of cells
2. only capable of 1 life function
i.e. reproduction & only within a living cell
 outside cells, viruses are lifeless chemicals
Typical Viral Stucture
Viral Capsids
Viruses come in many shapes.
Examples
Viral Classification
Viruses are generally classified by:
1. the organisms they infect
 host range (types of cells that the virus can infect)
 examples: a) cold virus
b) rabies
c) HIV
d) bacteriophage
2. structure
a. size and shape of the capsid
b. type genetic material (DNA or RNA)
Viral Size
 very small, measured in units called
nanometres (nm)
 1nm = 1X10-9 m
(billionth of a metre)
 size ranges from 20 - 400 nm
Homework
Questions page 107 # 1, 2, 5 – 8
SBI 3C
Viruses and Human Health

Most viral infections are difficult to _____________, they are not ______________________ by antibiotics.
antibiotics - inhibits the _______________ of or __________________ bacteria

Some viruses can remain ____________________ for years before symptoms appear.

Certain viruses cause ______________ by adding specific _______________ to an infected cell.
vaccine - liquid preparation of __________ or weakened _______________ or bacterial cells that stimulate
the body’s ______________________ system to fight back.
Influenza (FLU)

Usually considered to be more ___________________ than dangerous

Spread by ________________ contact and can live for ___________ in dry _______________.

First host: cells in the ____________ _____________________ tract

Sore ______________, congested _______________, chills, ______________, pain, sweating…

Contagious ___ day before symptoms appear, up to _______________ days after.

Incubation ____________ days

Last up to ____ weeks

Influenza vaccine can be ______% effective
Viral Reproduction
Viruses can reproduce only within a host cell because:
a) lack specific __________________ and ribosomes (necessary to make new cores & capsids)
b) have no __________________ of their own (needed to synthesize their parts)
There are 2 modes of viral reproduction
1. Lytic Cycle: all ________ viruses reproduce this way
2. Lysogenic Cycle: mostly ___________ viruses use this cycle
Difference between RNA and DNA viruses
RNA viruses
DNA viruses

e.x. common cold

e.x. chickenpox

Unstable they change their _______________
coat and “fool” the immune system

Stable and are the ____________ throughout
infection
Why do we need a Flu shot once a year?
The Lytic Cycle
The Lytic Cycle
•
All DNA viruses reproduce with the ____________ cycle and are called _______________ (capable of
causing ________________ & extremely _______________________)
The Lysogenic Cycle

RNA viruses cannot ___________ over the host cell machinery directly

They must first _______________ their RNA to DNA.

To do this they have a special ______________ called __________________ ____________________.

Because this is a reverse process RNA viruses are called _____________________.
Retroviruses are especially _______________ to their hosts because the viral _______ produced by this
enzyme can ____________ into (join with) the host chromosome and stay _________________ or latent for
months or years.

When each host cell ________________, it also copies the viral DNA '_________________' within its
own chromosome.

During this dormant period, the host's _________________ system does not 'see' the viral DNA and
produces no _____________________ against it.

The host feels _____ symptoms, but carries the disease and may _______________ others.

Examples of diseases caused by retroviruses are ______________, genital _____________ and cold
sores.

Some unknown stimulus will '______________' the viral genes to become active, take over the cell's
protein ________________ and continue as in the lytic cycle.
Steps Of The Lysogenic Cycle
Viruses & Human Health
Viral diseases are difficult to treat because:
1. No drug is available to _________ viruses in the body
2. Some viruses are ____________________  can remain dormant for years (hide inside cells)
ex. a) Herpes Simplex Virus I (HSV I) (___________ _____________)
b) HIV (____________)
3. some viruses are _____________________
• cause cells to become ____________________
onco = tumour
(genital warts)
(cervical cancer)
ex. Human Papiloma Virus (_______)
Protection Against Viral Diseases
vaccines: only true protection against viral diseases
people are given a dead or weakened form of the virus
builds up an army of WBC’s & antibodies to kill the living virus immediately before it can reproduce
ex. polio vaccine, hepatitis B vaccine
antiviral agents: drugs given after infection to slow the reproduction of the virus
ex. Valtrex – helps heal and decrease pain (herpes)
Viral Uses In Medicine
Viral Vectors
Viruses can be used for gene therapy as “carriers”
Viral core is removed & desired human gene is added
Virus is mixed with living cells
Virus attaches to human host
cell & injects the human gene
i.e. acts like a microscopic hypodermic needle
AIDS - HIV (Human Immunodeficiency Virus)
virus that causes AIDS
RNA core (retrovirus)
can only infect helper T cells (type of white blood cell)
cannot survive outside the body because glycoprotein membrane around its capsid dries out
(membrane picked up as it buds off white blood cell)
can only be transmitted from 1 bodily fluid to another
ex. 1. blood to blood: needles, transfusions, toothbrushes
2. semen & vaginal secretions
1. breast milk
HIV positive:
virus is in its lysogenic cycle (dormant)
patient is not sick, but is a carrier of the virus
can infect others
AIDS (Acquired Immunodeficiency Syndrome)
patient has symptoms of the disease
(begins when HIV enters the lytic cycle)
WBC’s are being destroyed
Early symptoms: night sweats, diarrhea, cold symptoms
AIDS Associated Disease
Late Symptoms
• Gastrointestinal: Cause most of illness and death of late AIDS
• Symptoms:
Wasting (extreme weight loss)
Abdominal pain
Infections of the mouth and esophagus
• Respiratory: 70% of AIDS patients develop serious respiratory problems
Bronchitis
Pneumonia
Tuberculosis
Lung cancer
More Associated AIDS Disease
•
Skin Disorders: 90% of AIDS patients develop skin or mucous membrane disorders
• Herpes
• Thrush
• Eye Infections: 50-75% patients develop eye conditions.
• Dry eye syndrome
The ultimate fate of a patient with AIDS
• patient dies from other infections due to a lack of immune response
ex. pneumonia, cancer
Drug Therapy
•
•
•
•
•
Reverse Transcriptase Inhibitors: Competitive enzyme inhibitors. Example: AZT, ddI, ddC
Protease Inhibitors: Inhibit the viral proteases. Prevent viral maturation
Problem with individual drug treatments: Resistance
Drug Cocktails: A combination of:
• One or two reverse transcriptase inhibitors
• One or two protease inhibitors
Drug cocktails have been very effective in suppressing HIV replication and prolonging the life of
HIV infected individuals, but are not considered to be a cure
Viral Uses In Medicine
1. Oncolytic viruses used in targeted cancer treatment
Choose a nonpathogenic virus that can infect human cells is chosen ex.
Vaccinia (cowpox)
Allow this virus to attack human tumour cells
After reproducing, viruses released kill host cancer cell i.e. lytic cycle
New viruses infect neighbouring tumour cells
Also stimulate immune system, bringing WBC’s in to help kill cancer cells
Note: cancer  is caused by a mutated ‘stop’ gene
 results in uncontrollable cell division