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An overview of the prokaryotic domains, including bacteria with their various structures and differences between species, archaea and their extreme environments, and viruses with their structure and reproductive cycles. It also covers pathogenic bacteria and viruses, as well as the concept of emerging viruses and viral vaccines.
What you will learn
Typology: Summaries
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The prokaryotic domains
Prokayotes (bacteria)
Size (range from 0.2 mm to 700 mm).
Shape (rod, spherical, spiral)
Gram stain results Gram negative
Gram positive
Presence or absence of flagellum.
Anaerobic vs aerobic
Prokaryotes and animals
Herbivores need bacteria to digest cellulose
Humans need bacteria to make Vitamin K & vitamin B12.
Termites need bacteria to digest wood.
Bacteria and plants
Live in the soil
Help legumes (beans) trap nitrogen
Bacteria are recyclers
Releases nutrients back into the environment
Break down a lot of chemicals
A hot area of research for oil spills.
Pathogenic bacteria
Many anaerobic bacteria cause disease Botulism, tetanus
Bubonic plague (black death)
Leprosy
Tuberculosis
A. Structure of Viruses: Infectious particles consisting of: Nucleic acid genome (DNA or RNA) Protein coat = capsid Lipid bilayer = envelope
Capsids and Envelopes
Main capsid types:
Envelopes
Contain membrane glycoproteins: Bind to specific host cell protein = “viral receptor”
remember that glycoproteins act as identifying signals.
Features of viral reproductive cycles
another organism (its host) at the expense of that organism.
Viruses cannot reproduce without a host cell.
No way to undergo mitosis or meiosis.
Obligate intracellular parasites
Viruses require from hosts:
Rabies virus
Ebola virus
Pathogenic virus: a disease- causing virus
Emerging viruses: sudden appearance (or sudden medical importance)
Examples: Avian bird flu
Viral vaccines
Viruses or viral components used to stimulate immune system defenses (without causing the disease).
Killed virus Flu shots, hepatitis A
Viral protein(s) Human papilloma virus (HPV)
Humans: H1N1 - 1918 “Spanish flu” H2N2 - 1957 “Asian flu” H3N2 - 1968 “Hong Kong flu” H5N1 - 2005 “Avian flu”
Why are we
fearful about
H5N1 (avian flu)?
But not easily transmitted: Poultry to human
Human to human
Immunity (^) No immunity
HA (a foreign protein)
Pathogenic viruses
Disastrous for North American natives Why?
Two known repositories Atlanta, Georgia Russia
Pathogenic viruses
Cervical cancer survival rate has improved with pap smears and other screening. Stage 1: 80 – 90% survive Stage 2: 50 – 55% survive Stage 3: 15 – 25% survive
Pathogenic viruses
Measles is highly contagious 90% of exposed people will develop measles.
German measles (rubella) in pregnant women will cause serious birth defects in fetus
Consuming prion-infected tissue (mostly neural)
Transmission of BSE (^) Prion disease transmission
Medical puzzle that stumped researchers because it affected mostly women and children.
Mystery solved in the 1950s when it was discovered that the Fore tribe was cannibalistic, eating their dead relatives’s brains as a funeral rite.