Transcript Viruses and Bacteria

Viruses and Bacteria
Ms. Stroup
8th Grade Science
Microbiology
Warm-Up
Pretend you went to a foreign country where
people knew nothing about infectious
diseases. You notice people are infected with
influenza.
• Q)How would you explain to someone what
the flu is, how they got it, and what it is doing
to their body?
(Only write the question)
Viruses
Viruses
• Viruses are NOT classified as organisms
because they are NOT free-living cells
• They need a host cell to live and reproduce
• They are composed of nucleic acid (DNA or
RNA) and a protein coat.
How viruses make you sick..
• Viruses invade
healthy cells and
use the enzymes
and organelles of
the host cell to
make more viruses.
– This usually kills the
host cell in the
process
Viral Replication- Lytic Cycle
1) The virus attaches itself to the cell membrane of a
host cell.
2) The virus (or its genetic material) penetrates the
cell.
3) The enzymes in the host cell uncoats the virus’
capsid.
4) The virus’ genetic material is released into the host
cell and begins to make copies in the cells nucleus.
5) New genetic material is enclosed in a new capsid,
and a copy of the virus is released out of the cell
membrane…ready to invade a new healthy cell.
Viral Transmission
• Human Contact or insect bite
• Viral diseases are the most widespread illness
in humans.
• Diseases can range from being mild like the
common cold to sever and fatal diseases like
cancer or HIV/AIDS.
Prevention/Treatment
• Vaccines
• Anti-viral drugs
(stop virus from
reproducing)
Influenza Pandemics!!!
• Occur when a new subtype of a virus arises
• Humans have no or little immunity to it so
everyone is at risk
• Causes serious illnesses worldwide,
sometimes in only 6-9 months
1.
Influenza Pandemics!!!
• Spanish influenza killed 40-50 million people
in 1918
• Asian influenza killed 2 million people in 1957
• Hong Kong influenza killed 1 million people in
1968
1.
Bacteria
1.
1.
Bacteria Facts
• Prokaryotic, single-celled
organisms
• Can live in a variety of places
– With oxygen
– Without oxygen
– Extreme heat
– Extreme cold
– Below and on\Earth’s surface
– Existed for billions of years!
1.
Bacteria Shapes
• Cocci are Spherical
•
Bacilli and rod shaped
•
Spirilla and spirochetes are
spiral shaped
How Bacteria Reproduce
• Binary Fission
– A form of asexual
reproduction.
– The genetic material
duplicates and the
cell divides into two
identical cells.
– Bacteria can grow
and divide extremely
rapidly!
How Bacteria Can Cause a Disease
• Prevent the host tissue from working properly
• Produce toxins which can destroy the host
tissue
Bacteria is not always harmful!
Beneficial
• Decompose trash in
landfills
• Digest food
• Produce vaccines
• Preparation of foods
– Yogurt
– cheese
Harmful
• Bacteria can cause
many illnesses
– Strep-throat
– Tuberculosis
– Pertussis
– Cholera
– Anthrax
– Leprosy
– Meningitis
Treatment
• Antibiotics
– Antibiotic resistance:
Because we have
overused antibiotics,
mutant bacteria can
survive antibiotic
treatments and give
rise to resist
treatment.
What diseases can you get from
animals or insects?
- Ticks = Lyme disease
- Mosquitos = West Nile/ Malaria/ yellow fever
- Dogs =
Rabies/Ringworm/hookworm/roundworm/
Tapeworms…and many more
- Reptiles = Salmonella
- Cat = Toxoplasmosis/ tapeworms