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Chapter 19 Bacteria and Viruses
19-1 BACTERIA19-2 VIRUSES19-3 DISEASES CAUSED BY BACTERIA AND VIRUSES
19-1 Bacteria
Bacteria are prokaryotes- unicellular organisms that lack a nucleus.
Classification was the Kingdom Monera
Now, in two separate Kingdoms: Eubacteria Archaebacteria
Bacteria
What’s the Difference? Eubacteria- new bacteria
Example: Escherichia coli (E. coli)
Found water, land, on and in us.
Archaebacteria- ancient bacteriaExamples: MethanogensFound in harsh environments:thick mud, digestive tracts of
animals, hot springs
Identifying Prokaryotes
Shape Cocci – spherical Bacilli – rod
shaped Spirilla - spiral
How do they obtain energy?
Most are heterotrophs and many are autotrophs
Types of heterotrophs: “other” Chemoheterotrophs (chemical) Photoheterotrophs (light)
Types of autotrophs: “self” Photoautotrophs (surface of lakes,
oceans) Chemoautotrophs (deep ocean)
Growth and Reproduction Can divide every 20 minutes! Two ways to reproduce:
Binary fission – dividing in half Conjugation – form bridge and exchange
DNA
When conditions become unfavorable: Spore formation – help it survive in
extreme conditions, such as heat, dryness, lack of nutrients.
Binary fission
conjugation
Spore formation
Importance of bacteria
Decomposers – Help ecosystem
recycle nutrients by breaking down dead tissue
Help in sewage treatment
Human Uses
Used in industry – clean up oil spills Remove wastes and poisons from water Make drugs Used in food
19-2 Viruses
Viruses are composed of a core of DNA or RNA surrounded by a protein coat (capsid)
Virus means poison
Virus Structures
T4 BacteriophageTobacco Mosaic
Virus Influenza Virus
RNACapsid
Surfaceproteins Membrane
envelope
RNA
Capsidproteins
Head
Tail sheath
DNA
Tail fiber
How does a Virus work?
Proteins of virus bind to receptors on the surface of a cell.
Cell gets “tricked” into letting the viral DNA in.
Cell then transcribes and translates viral genes.
Bacteriaphage- infects bacteria
Viral Replication
Two different processes can occur:
Lytic Cycle: viral DNA enters host, copies are made, and cell lyses (bursts).
Lysogenic Cycle: viral DNA enters host, viral genes are replicated indefinitely. Prophage- viral DNA incorporated in cell’s
DNA
The Lytic Cycle...
The Lysogenic Cycle...
Both Cycles...
Retroviruses
Retrovirus- contains RNA as its genetic information
Genetic info is copied backwards from RNA to DNA.
“Retro” means “backwards”
Ex. AIDS is caused by a retrovirus (HIV)
Comparison…
19-3 Diseases caused by Bacteria and Viruses
Disease causing agents are pathogens
Bacteria produce disease in one of two ways:Break down cells for foodRelease toxins (poisons)
Examples for food or toxin release
TB – tuberculosis – destroys lung tissue
Strep throat - releases toxins into blood stream
SMALL POX
COLD VIRUS
EBOLA
FLU
Tooth decay
Lyme disease
Tetanus
Tuberculosis
Salmonella food poisoning
Pneumonia
Cholera
Streptococcus mutans
Borrelia burgdorferi
Clostridium tetani
Mycobacterium tuberculosis
Salmonella enteritidis
Streptococcus pneumoniae
Vibrio cholerae
Regular dental hygiene
Protection from tick bites
Current tetanus vaccination
Vaccination
Proper food-handling practices
Maintaining good health
Clean water supplies
Disease Pathogen Prevention
Section 19-3
Common Diseases Caused by Bacteria
Diseases caused by Bacteria
Controlling Bacteria
Sterilization – using high temperatures
Disinfectants – chemical solutions
Food storage and processing – storing in fridge or cooking food
Preventing Bacterial Disease
Vaccine – weakened or killed pathogenExamples – meningitis, whooping
cough
Antibiotics – block the growth and reproduction of bacteriaExamples- Penicillin or tetracycline
Oncogenic viruses
Retrovirus
Adenoviruses
Herpesviruses
Poxviruses
DNA
RNA
DNA
DNA
DNA
Cancer
Cancer, AIDS
Respiratory infections
Chickenpox
Smallpox
Type of Virus Nucleic Acid Disease
Section 19-3
Common Diseases Caused by Viruses
Diseases caused by Viruses
Viral disease in humans
Cannot be treated with antibiotics
VaccinesExamples – polio, measles, mumps,
chicken pox, hepatitis b
