Warm - Up
What is the difference between a
bacteria and a virus?
• What is the difference between a bacteria
and a virus?
– Bacteria – a domain of unicellular
prokaryotes that have cell walls containing
peptidoglycans.
– Virus – a particle made up of nucleic acid,
protein, and in some cases lipids that can
replicate only by infecting living cells.
Concept Map
Section 19-1
Bacteria
are classified into the kingdoms of
Eubacteria
Archaebacteria
include a variety of
lifestyles such as
Living in soil
Infecting large
organisms
live in harsh
environments such as
Thick mud
Animal
digestive
tracts
Salty lakes
Hot springs
Eubacteria:
Prokaryotic
More species
Found everywhere
Cell walls of peptidoglycan
Archeabacteria:
Prokaryotic
No peptidoglycan
Different lipids in its membrane
Found in harsh environments
DNA sequences similar to eukaryotes
• The domain Archaea
• Include prokaryotes that do not
have peptidoglycan walls
• 3 major groups:
Methanogens
Extreme halophiles
Extreme thermophiles
Thermophiles
• Extreme thermophiles. Live at
very high temperatures: ocean
hydrothermal vents (up to 113o
C, which would be boiling
except for the high pressure
under the ocean), hot springs in
Yellowstone National Park.
• Use sulfur to generate energy
just like we use oxygen: donate
electrons to sulfur to create
hydrogen sulfide. Some
generate sulfuric acid instead—
they live at very low pHs.
Basic Bacterial
Shapes
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•
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•
Three basic shapes:
Coccus
Bacillus
Spirilum
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•
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Common Prefixes:
Diplo - two
Tetra - four
Staphylo - cluster
Strepto - chain
Bacterial morphologies (1)
Assorted Shapes
How do bacteria eat?
Bacterial
Reproduction
• Binary fission
One cell divides into two cells
• Conjugation
Cells exchange genetic information
• Endospores
Thick wall around DNA for protection
Viruses—Size
• Here is how you can imagine the size of
viruses:
“If a virus was the size of a basketball…”
• A bacterium would be as large as a city
block
• A grain of sand would be two miles long
• A person would be 4,000 miles tall
BioEd Online
Figure 19-9 Virus Structures
Head
RNA
DNA
Capsid
RNA
Capsid
proteins
Tail
sheath
Tail
fiber
Surface
proteins
T4 Bacteriophage
Tobacco Mosaic
Virus
Influenza
Virus
Membrane
envelope
What Are Viruses Made Of?
• Viruses are composed of
nucleic acid, proteins, and
sometimes, lipids.
• *Nucleic acid, which can be
either DNA or RNA, encodes
the genetic information to
make virus copies.
• *The nucleic acid is
surrounded by a protective
protein coat, called a capsid.
• *An outer membranous layer,
called an envelope, made of
lipid and protein, surrounds
the capsid in some viruses..
Envelope
Nucleic acid
Capsid
• Lytic Infection- host cells are lysed and
destroyed.
• Lysogenic Infection– Virus DNA inserts into the host’s DNA
– Lysogenic infections lead to lytic infections
Lysogenic
into the
Lytic Cycle
Figure 19-11 Viruses and Cells
Sectin 19-2
Viroids
Prions
- No DNA or RNA
- Strand of RNA - No capsid.
Only
a
protein
- Can reproduce
(glycoprotein) – that
inside cell
can enter into cells
and cause disease
- No capsid
Common Diseases Caused by Bacteria
Section 19-3
Disease
Pathogen
Prevention
Tooth decay
Streptococcus mutans
Regular dental hygiene
Lyme disease
Borrelia burgdorferi
Protection from tick bites
Tetanus
Clostridium tetani
Current tetanus vaccination
Tuberculosis
Mycobacterium tuberculosis
Vaccination
Salmonella food poisoning
Salmonella enteritidis
Proper food-handling practices
Pneumonia
Streptococcus pneumoniae
Maintaining good health
Cholera
Vibrio cholerae
Clean water supplies
Common Diseases Caused by Viruses
Section 19-3
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
DNA
Cancer
Retrovirus
RNA
Cancer, AIDS
Adenoviruses
DNA
Respiratory infections
Herpesviruses
DNA
Chickenpox
Poxviruses
DNA
Smallpox
Retrovirus
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•
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Possesses RNA rather than DNA
HIV is a retrovirus
Human Immune Deficiency Virus
Acquired Immune Deficiency Syndrome
Electron Microscope Pic of HIV