Carriers of Disease Microbes, Germs and Other Scary Things

Bacteria Prokaryotic, monera 2 billion yrs 1 st 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 1 st 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 1 st 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 st 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 Athletes foot Ringworm Vaginal yeast infections Lung infections Nail infection