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microbes in our lives
bacteria, fungi, protozoa, microscopic algae, and viruses
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pathogenic
disease causing
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Group of 3 domains
- Bacteria: Prokaryotic cells; cell walls made of peptidoglycan
- Archea: Prokaryotic cells; if cell wall, lack peptidoglycan
- Eukarya: Eukaryotic cells; protists, fungi, plants, animals
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bacteria
what kind of organism?
Prokaryotic?
Cell wall?
Nutrition?
Movement?
Reproduction?
- Simple, unicellular organisms
- Prokaryotic: genetic material not surrounded by membrane
- Cell wall: made up of pepetidoglycan
- Nutrition: organic chemicals, inorganic Chemicals, or photosynthesis
- Movement: "swim" using flagella
- Reproduction: binary fission
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archae
what kind of organism?
Prokaryotic?
Cell wall?
Nutrition?
Movement?
Reproduction?
- simple, unicellular organisms
- Prokaryotic cells: genetic material not surrounded by membrane
- Cell wall: may or may not have; if they do, no peptidoglycan
- Nutrition: organic chemcials, inorganic chemicals, or photosynthesis
- Movement: "swim" using flagella
- Reproduction: binary fission
- found in extreme envrionment (high salt, high temperature, etc) and not known to cause disease
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Viruses
What kind of microscope can see viruses?
Acellular?
Reproduction?
- can only be seen with electron microscope
- Acellular: not cellular (therefore no "cell" wall); very simple structure
- Reproduction: only inside host cell
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Normal Microbiota
- also known as flora, microbes on and in our bodies
- 1. Don't usually cause harm; often beneficial
- Prevent over-growth; produce vitamins
- 2. Cause harm if they leave normal habitat.
- 3. Our resistance (the ability to ward off diseases) determines if microbes is harmful
- Skin, chemicals produced by normal flora, stomach acid, white blood cells, fever, etc
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Infectious Diseases
- 1. Pathogen invades susceptible host,
- 2. Spends part of its life cycle in the host,
- 3. Disease results from the microbe or it's products
- End of WWII, thought to be "under control".
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Emerging Infectious Diseases: (EIDs)
- new or changing diseases
- 1. Factors contributing to EIDs:
- Evolutionary changes in existing organisms
- Modern transport: spread known diseases to new regions/ populations
- Increased human exposure to new agents due to human spread and activities
- 2. Example of EID:
- Avian influenza A (H5N1) virus:
- 2003: millions of poultry & 24 people in 8 countries
- Subtype of Influenza A foundi n many animals; usually species specific
- Sometimes cross over and cause illness
- As of 2008: 242 people; 50% mortality
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Chemotroph
organic/ inorganic molecules as energy source
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Phototroph
light as energy source
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Heterotroph
organic molecules as carbon source
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Chemoheterotroph
organic/ inorganic molecules as energy source; organic molecules as carbon source
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unicellular
yeasts (single cell, eukaryotes)
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multicellular
filamentous (molds), or fleshy (mushrooms)
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thallus (body)
consists of long filaments of cells joined together; these filaments are called hyphae.
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Vegetative hyphae
portion that obtains nutrients
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Aerial hyphae
portion used for reproduction
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Harmful effects of fungi
- fungal infections increasing due to increase in patients with compromised immune systems
- more than $1 billion/ year in crop damage
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Beneficial of fungi
- recycle vital elements
- Make: foods (bread); drugs (penicillin)
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General description of fungi
Cell wall?
Nutrition?
Reproduction?
- Cell wall: chitin
- Eukaryotic cells (genetic material is surrounded by a membrane)
- Nutrition: chemoheterotrophs; decompose and absorb nurtirnets from environment
- Reproduction: sexual or asexual
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Dimorphic Fungi
- Two forms of growth: mold-like or yeast-like
- Pathogenic species: yeast-like at 37'C, mold-like at 25'C
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Background of Algae
Cell wall?
Nurtrition?
Reproduction?
- Cell wall: cellulose
- Uni- or multicellular Eukaryotes
- Nutrition: photoautotrophs; lack tissues of plants
- Reproduction: sexual (meiosis) or asexual (mitosis)
- Do not cause infections
- Diseases result from toxins produced by algae.
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Protozoal and Helminth Hosts:
- Stage of parasite development determines the host type:
- intermediate host: harbors larval or asexual stage of the parasite
- definitive host: harbors adult, sexuallymature parasite
- Eukaryotic cysts: protective capsule; survival when conditions are not optimal; transmission
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Background of Protozoa
Eukaryotic cells?
Unicellular?
Cell wall?
Nutrition?
Movement?
Reproduction?
- General description:
- Eukaryotic cells
- Unicellular
- No cell wall
- Nutrition: hetertrophs; free-living or parasites that ingest, photosynthesize, or absorb nutrients
- Movement: pseudopods, flagella, or cilia
- Reproduction: sexual or asexual
- Live in animals, water, or soil
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Medically Important Protozoa:
Superkingdom Excavata: Archaezoa:
9 points
- multiple flagella
- Mitosome instead of mitochondria
- Found in animal digestive tracts
- Ex 1: Giardia lamblia:
- Glardiasis: amoebic dysentery
- Excreted in feces as cyst; ingested by next host.
- Ex 2: Trichomonas vaginalis:
- Urinary tract infections
- Transmitted: towels, toilets, sexual contact
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Medically Important Protozoa:
Superkingdom Excavata: Euglenozoa:
2 points and 2 examples
- Euglenoids (photoautotrophs) and Hemoflagellates (blood parasites)
- Hemoflagellates transmitted by bites of insects feeding on blood; found in circulatory system
- Ex 1: Trypanosoma: Chagas disease; transmitted by the "kissing bug"
- Ex 2: T.brucei: African sleeping sickness; transmitted by tsetse fly
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Medically Important Protozoa:
Amebae:
4 points and 2 examples
- move by pseudopods
- Ex 1: Entamoeba histolytica:
- Intestinal pathogen; cysts excreted in feces, ingested by next host
- Ex 2: Acanthamoeba:
- Grows in water
- Infect cornea; can cause blindess
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Medically Important Protozoa:
Apicomplexa:
4 points and 1 example
- Obligate intracellular parasites
- Organelles at cell apexes; contain enzymes to penetrate host tissues
- Have complex life cycles; several hosts
- Ex 1: Plasmodium sp: malaria
- Definitive host Mosquito (Sporozoite) --> Intermediate host Human (Merozoite)
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Medically Important Protozoa:
Ciliates:
4 points and 1 example
- movement and bring food to mouth
- complex cells
- Ex 1: Balantidium coli:
- Dysentery
- Only human parasite in this group
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Helminths: Parasitic Worms
Background?
- A. Background:
- 1. Multicellular eukaryotic animals; most possess digestive, circulatory, nervous, etc. systems.
- 2. Parasitic (medically important) or free-living.
- 3. Complex life-cycles:
- may invovle multiple intermediate hosts for development of each larval stage
- definitely host for adult parasite
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Kingdom: Animalia
3 points
- Phylum: Platyhelminthes (faltworms)
- Classes: Trematodes (flukes) & Cestodes (tapeworms)
- Phylum: Nematodes (roundworms)
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Trematodes (flukes)
4 points
- 1. flat, leaf-shaped bodies, with suckers.
- 2. absorb food through their surface (cuticle)
- 3. named according to tissue adult lives in: liver fluke, lung fluke, etc.
- 4. humans as a definitive host
- adult fluke release eggs in human lung --> eggs excreted in feces --> eggs reach water --> larvae hatches in water, infects intermediate host --> intermediate host eaten by human --> develops into adult
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Cestodes (tapeworms): intestinal parasites
4 points
- 1. Scolex (head) has suckers or hooks for attachment
- 2. Absorb nutrients through cuticle
- 3. Proglottids: segements; have male and female reproductive organs; in feces they are diagnostic of a tapeworm infection
- 4. Humans as an intermediate hosts
- adults tapeworm release eggs in definitive host --> eggs excreted by definitive host --> intermediate host (human) eats egg --> definitive host eats intermediate host --> matures into adult worm
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Nematodes (roundworms)
7 points and 2 examples
- 1. Completes digestive system; most have separate male and female worms
- 2. Free-living in soil and water or parasites of plants and animals
- 3. Human infections divided into two categories:
- Eggs infective for humans:
- - Ex. Pinworms
- Pinworm eggs in soil --> eaten by humans --> become adult pinworms in large intestine
- can be transmitted human to human by clothing or bedding
- Larvae Infective for humans:
- Ex. trichinella spiralis
- trichinella larvae cysts in undercooked pork --> human eats pork --> trichinellosis
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Arthropods as vectors:
Arthropods:
3 points
- 1. Animals with segemented bodies, external skeletons, and jointed legs
- spiders, mites, ticks, flies, lice, etc.
- 2. Vector: organism that carry pathogenic microbes
- 3. Infection trough: mechanical transport or feeding
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