Unit 5:
Objectives:
1. Know the characteristics of bacteria.
2. Know what bacteria need for survival.
3. Know the difference between asexual and sexual
reproduction.
4. Know how bacteria reproduce.
5. Know how bacteria can be helpful and harmful.
6. Know how viruses reproduce.
7. Know how bacteria and viruses are different.
Kingdom Monera (Bacteria)
Main Characteristics:
• Made up of only one cell (unicellular)
•Contain a cell wall
•Do NOT contain a nucleus (Prokaryotic)
• Most can not move from place to place
• To obtain energy they feed off of dead
organisms (decomposers)
• Reproduce asexually (no sperm and egg)
Survival
In order to survive, bacteria need:
• Water
• Proper temperature
• Most need oxygen (aerobic)
• Energy (decomposers)
Shapes of Bacteria
Cocci: sphere shaped
Bacilli: rod-shaped
Spirilla: spirals
Reproduction
Asexual: • No exchange of genetic material
• No sperm and no egg
• Offspring are identical to parent
Sexual: • Exchange of genetic material
• Sperm and egg
• Offspring are different from parent
Reproduction in Bacteria
Asexual reproduction occurs by binary fission.
Binary Fission: one organism divides into two identical
organisms.
Bacteria reproduce about every 20 minutes.
40 min
0 min
20 min
Proper temperature and moisture are required.
Endospores, a thick protective covering, surround
bacteria if proper conditions are not available.
Harmful Bacteria
• Spoil food
• Cause diseases in plants and animals
Helpful Bacteria
• Help make foods; cheese, yogurt, butter
• Help breakdown dead material
• Some help fight other bacteria
• Make chemicals or drugs to help people
(example: insulin)
• Found inside small intestine of humans to help
digest food.
• Some make nitrogen compounds for plants.
Viruses
A microscopic particle that invades a cell and often
destroys it.
Characteristics:
• Smaller than bacteria
• Can NOT “live” on its own. A host cell is required
for reproduction.
• Genetic material is enclosed in a protein coat.
• Do NOT carry out all of the processes of living things.
Viruses are NOT living organisms!
Shapes of Viruses
- crystals
- spheres
- cylinders
- space crafts
Reproduction
Asexual reproduction occurs in viruses through the
lytic cycle.
• Many viruses are made inside a host cell.
• The cell bursts to release the viruses.
• Each newly made virus then attacks a
different cell and repeats reproduction.
Lytic Cycle
1. The virus finds a host cell.
2. The virus enters the cell or
injects genetic material into the
cell.
4. The new viruses break out of the
host cell and find new host cells.
3. The virus’s genes turn the
cell into a virus factory.
Objectives:
• Know the difference between non-infectious and
infectious diseases.
• Know what causes infectious diseases.
• Know how infectious diseases are spread.
• Know how to protect yourself against disease.
• Know how your immune system fights diseases.
Disease
Something that causes your normal body
functions to become disrupted.
Two types of disease:
• Non-infectious
• Infectious
Non-infectious Disease
• No presence of a “living” organism inside
the body.
• Can NOT be spread from one living
organism to another.
• Examples: cancer, asthma
Infectious Disease
• Presence of a “living” organism inside
the body.
• Can be spread from one living
organism to another.
• Examples: Malaria, cold
Infectious diseases are caused by pathogens.
You call them germs!
Pathogens
An organism that causes disease.
Kinds of Pathogens:
• Bacteria
• Viruses *(not living)
• Fungi
• Protists
How Pathogens are Spread
1. Through the air. Example: sneezing, talking
2. Touching contaminated objects.
Ex. door knobs, books, towels, drinking glasses
3. Person to person
Ex. kissing, shaking hands
4. Infected animals
Ex. being bitten or scratched by a sick animal
5. Soil, food and water
Ex. eating undercooked food, unwashed fruit or veggies,
drinking dirty water
How to Protect Yourself Against Disease.
1. Wash your hands frequently.
2. Cover your mouth when you sneeze and cough.
3. Stay away from animals that are acting strange or
are unknown to you.
4. Wash your fruits and vegetables.
5. Wash areas where raw meat has been.
6. Do NOT eat raw or undercooked meat or eggs!
How to Prevent Disease
Pasteurization: Developed by Louis Pasteur in
1800’s.
Heating liquids to kill bacteria in
wine, milk and cider.
Vaccine: An injection that contains a weak or
dead pathogen.
Your body recognizes and fights the
pathogen but you do not get
symptoms.
Immunity: Resistance to a disease.
Fighting a Disease
Antibiotics: A medicine that will kill or slow the
growth of bacteria and fungi.
Antibiotics do NOT work on viruses!
Immune System:
Macrophage: Engulf or eat pathogens inside body.
T cells: Kill infected cells and activate B cells.
B cells: Make antibodies, proteins, for each specific
pathogen allowing them to be destroyed.
Remember pathogens to fight infection faster if you
come in contact with the same pathogen again.