Transcript Carriers of Disease

Carriers of Disease
Microbes, Germs and Other Scary
Things
Bacteria
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Prokaryotic, monera
2 billion yrs
1st life on earth
They change and adapt to the
environment
• No cell membrane or nucleus
• Have cell wall
• Many different structures
Habitat
• Extremes
– Hot
– Cold
– Acidic
– Alkaline
• Everywhere on earth
• Minority cause disease
• Majority are essential to life on earth
Diversity
• 2 groups
– Archeabacteria –halophytes,
themoacidophiles, Methogens – poisoned by
O2
– Eubacteria –all others
• Pathogenic eubacteria cause about ½ of all human
disease
• Some destroy tissue
– Exotoxins secrete substances that cause disease
– Endotoxins – parts of the cells cause fever or shock
Motility
• ½ make direct movement
• Flagella – most common form of
movement, extension of plasma
membrane
• Spirochetes – spiral shaped that may have
slimy chemicals excreted and a flagella
• Taxis – have an attraction to chemical that
may be beneficial or harmful
Virus
• Simplest form of life
– Argument can be made that they may not be
living
• 1st discovered by Dr. Mayor in tobacco
plants
• Very small 20nm diameter
• Consist of viral genes enclosed in capsid –
a protein shell
• There are multiple types of protein
• Envelopes covering on capsid taken from
the membrane of host
• Phages – virus that infect bacteria
RNA viruses
• Single strand of nucleaic acid molecule
involved in protein synthesis
– Structure is specified by DNA
• Retrovirus – most complicated
reproduction
– Can reverse DNA to RNA
– New DNA integrates into host cell
Evolutionary origins
• Evolved after 1st cells from fragments of
nucleacic acid
• Developed capsid to promote infection
• Viral genomes – plasmids – transposes
DNA segments that move along genome
• Virus replicate using the entire cell it
infects
Prion
• Cause disease but aren’t bacteria, virus,
parasite or fungi
• They are protein and not alive
• 1986 1st public awareness with onset of
Mad-Cow Disease
• Enter cell where they convert normal
protein found within cell into prions like
themselves
• When normal cell is transformed into prion the
amino acids are folded into alpha helical
structures and relax into beta sheets
• Prion then clog cells which decreases function or
stops the cell from functioning all together
• In brain tissue prion-bloated brain cells dies and
release prion into tissue leaving holes in brain
matter
• Cause disease call spongiform
encephalopathies
Parasites
• Single cell or multicell organism that feeds
off host
• Can survive only if host lives
• Causes disease that are usually not fatal
• Too many variety to list
Fungi
• Ecosystem would collapse without fungi
– Decomposers
– Recycles chemical elements in the
environment
• Positive uses for humans
– Food
– Cultures to produce antibiotics
– Makes bread rise
– Ferments to create beer and wine
Characteristic
• Eukaryote, multicellular
• Heterotrophic
• Excretes enzymes that break down
molecules which it then absorbs\
• Can be parasitic or mutualistic
Unique Lifestyles
• Molds – grow as parasites on variety of
substrates
– Ex. – bread mold
• Yeast – inhabit moist environments or
liquids
– Ex. - Candida
Pathogenic Yeast in Humans
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Athletes foot
Ringworm
Vaginal yeast infections
Lung infections
Nail infection