Bacteria and Viruses!
Vocab—Hooray!
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Prokaryote
Bacillus
Coccus
Spirillum
Pathogen
Virus
Capsid
Vaccine
Antibiotic
Prokaryotes—Quick Review!
•Prokaryotes are single celled organisms that
do NOT have a membrane bound nucleus.
•Prokaryotes are the most numerous
organisms on Earth and live almost
everywhere—every square centimeter!
•Most prokaryotes are BACTERIA
Identifying Prokaryotes
• Prokaryotes are
identified by 3
characteristics:
Shapes
• 3 shapes: rod, spherical, spiral
Cell Walls
• Thick walls, thin walls
Movement
• No movement, flagella, lash/snake/spiral
forward, glide on secreted material
Bacteria—3 Basic Shapes
Bacilli
Rod-Shaped
Cocci
Spirilla
Sphere Shaped
Spiral Shaped
Gram Stains and Cell Walls
• Bacteria can be classified into 2 categories based on the structure of
their cell walls using GRAM STAIN.
• GRAM NEGATIVE BACTERIA take up the red of the gram stain process,
turning reddish pink under a microscope
• GRAM POSITIVE BACTERIA take up the purple dye and look purple
under a microscope.
Bacteria—Structure and Function
• Cell wall, cell membrane, cytoplasm
• DNA, floating
• Capsule—outer covering made of
polysaccharides
• Pili—short, hair-like proteins on the surface of
the bacteria, helps bacteria attach to surfaces
and cells
Bacteria Review #1
Importance of Bacteria!
• Bacteria are VITAL to the living world
• Some are producers
• Some are decomposers
• Others have human uses (cleaning up oil, medicines,
human health)
Bacteria and Health (note: many bacteria are
good for us!)
• PATHOLOGY is the scientific study of disease
• EXOTOXINS are toxic substances that bacteria secrete into
their environment (tetanus)
• ENDOTOXINS are toxic substances that are part of the outer
membrane of bacteria and are not released until the cell dies
(E.Coli)
• ANTIBIOTICS are chemicals that inhibit the growth or kill
bacteria
• ANTIBIOTIC RESISTANCE is the evolution of populations of
bacteria to resist (and not die) antibiotics.
Bacterial
Diseases
Lyme Disease
Staph Infection
Flesh
Eating
Disease
Controlling Bacteria
Sterilization with Heat
• Destroys bacteria
• Exposes bacteria to
great heat
Disinfectants
• Chemical solutions
designed to kill
bacteria
• Overuse of
antibacterial
compounds can lead
to bacteria evolving
to resist them
Food Storage and
Processing
• Store food in fridge
(low temperatures
need more time for
bacteria to grow)
• Boiling, frying,
steaming will
sterilize bacteria
Bacteria in Review: Crash Course!
Bacteria Review #2
POGIL
Viruses!
A VIRUS is a nonliving particle made up or nucleic acid and a
protein coat (a CAPSID) and cause disease.
Viruses are VERY small
Viruses are NOT living because:
• They lack cytoplasm
• They lack organelles
• No metabolism or homeostasis
• Can only reproduce while in a host cell
VIRAL REPLICATION
• Outside the host cell, a virus is a lifeless particle with
no control over its movements
• It is spread by air, in water, in food, or body fluids
• A virus recognizes a host cell and then attaches to it
and the infection begins
• Once in a host cell the viruses DNA can make mRNA or
the viruses RNA serves as mRNA and they begin to
replicate more viruses
Viral Infection
• Once a virus is inside a host cell 2 different processes may occur—
Lytic Infection or Lysogenic Infection
Lytic Infection
• Virus enters the cell, makes copies of itself,
causes the cell to burst.
• When the cell bursts all of the copies are
released and can infect other cells
Lysogenic Infection
• Virus enters host cell, integrates its DNA into the DNA of the host cell,
and the viral DNA replicates along with the host cell DNA.
• The Viral DNA can remain in the cell for generations
• Eventually the viral DNA leaves and becomes a lytic infenct
How a Virus Works Video Clip
Viral Diseases
• Since viruses are lifeless they must be spread by
other agents…humans, animals, insects, etc.
• Common Viral Diseases:
• Chicken pox, shingles, viral hepatitis, HIV,
SARS, Avian Flu, West Nile, Influenza
•Virus Song!
Chicken Pox and Shingles
Virus Treatment
• Vaccinations and Vector Control
• A VACCINE is a solution that contains a harmless
version of the virus (inactive or weakened).
• VECTOR CONTROL is a the control of animal vectors
such as mosquito and rabies control
• Drugs/Medications do not work well on viruses
because it is hard to find something that can block the
virus but not harm the host cell.
Comparing Bacteria and Viruses
Comparing Bacteria and Viruses #2
• Watch the clips
• Create a t-chart to list characteristics of both
bacteria and viruses
• After the video clips, add to the t-chart
• Write an 8 sentence or longer paragraph to
compare and contrast bacteria and viruses.
Should Vaccinations Be Required?