Chapter 12

Eukaryotic organisms

• Mycology – study of fungi

• Heterotroph

• Absorb nutrients

• Yeasts – unicellular

• Molds – multicellular, filamentous

• Filaments – hyphae

• Fragment hypha can grow into a fungus

Aerial hyphae – reproductive sporesVegetative hyphae – absorb nutrientsCottony, fluffy

• Yeasts – unicellular

• Oval or circular in shape

• Many reproduce by budding

• Buds fail to separate from the parent

• Pseudohyphae are formed

• Candida albicans

Dimorphic fungi

• Mold-like - 25o C

• Yeast-like – 37oC

• Many fungi make asexual spores

• Different types of asexual spores

Septate hyphae – fragmentsSingle cells - Thick cell wallsCoccidiodes immitis

Pseudohypha – round and enlarged

Candida albicans

Rhizopus

Conidiospores - Penicillium

Sexual reproduction

• Two different strains• + and –• Pheromones - proteins• Attract negative strain – mate• + and - fuse to make zygote• Differentiates into a sexual spore• Environmental conditions• Nutrient depletion

Three groups of fungi

• Based on sexual spores

• Zygomycota

• Asexual spores – sporangiospores

• Sexual spores – zygospores

• Coenocytic hyphae

• Rhizopus

Ascomycota

• Some molds and some yeasts

• Molds – septate hyphae

• Asexual spores – conidiospores

• Yeasts reproduce by budding

• Sexual spores – ascospores

• Penicillium

Basidiomycota

• Mushrooms

• Septate hyphae

• Asexual – fragmentation of hyphae

• Sexual spores - basidiospores

Mycoses – fungal diseases

• Systemic mycoses – deep within the body

• Inhaling fungal spores

• Starts in the lungs – spreads to other parts

• Histoplasmosis – Histoplasma capsulatum

• Dimorphic fungus

• Conidiospores

• Soil enriched with bird droppings

• Minor respiratory infection

• Immune system is weak – spreads to liver, spleen, bone marrow

• Coccidioidomycosis – Coccidiodes immitis

• Arthrospores – soil – southwest – abundant in the soil

• Cough, Chest pain

• Amphotericin B

• Cutaneous mycosis – hair, nail, skin

• Ringworm, tineas

• Fungi – dermatophytes

• Keratinase – breaks down keratin

• Tinea pedis – athlete's foot

• Trichophyton rubrum

• Itching, scaling skin

• Direct contact, shower room floors

Opportunistic mycosis

• Candidiasis

• Candida albicans

• Normal flora

• Immune system weak

• Thrush – Candida infection of the oral cavity

• AIDS, newborns

Amanita phalloides

• Mushroom

• Death angel

• Neurotoxin

• Hallucinations

• Death within a week due to liver damage.

Claviceps purpurea

• Grows on grains – rye

• Toxin – ergot

• Ergotism

• Hallucination

• Constriction of the capillaries – gangrene

• Middle ages

Protozoa

• Unicellular – eukaryotic

• Soil, water, within the bodies of humans and animals.

• Trophozoites – metabolically active, reproduce, motile, inside the host

• Cyst – metabolically inactive, dormant, outside the host.

Entamoeba histolytica

• Pseudopods• Intestinal tract• Cysts are released in the feces.• Contaminated food or water.• Cysts – trophozoites – intestinal tract• Feed on cells lining the intestinal tract, red

blood cells.• Dysentery – bloody diarrhea

Giardia lamblia

• Flagella

• Intestinal tract – carriers

• Cysts are released in the feces

• Trophozoits attach themselves to intestinal wall

• Abdominal pain, diarrhea, weight loss

• Metronidazole

Balantidium coli

• Cilia for movement.

• Macronucleus - controls protein synthesis

• Micronucleus – transmits genetic information

• Cysts are transmitted in contaminated food or water

Hemoflagellates

• Long, slender body• Undulating (wavy) membrane• Flagellum• Trypanoasoma gambiense• African sleeping sickness• transmitted by tsetse fly• Grows in the bloodstream• Causes damage to the nervous system• Drowsiness, coma, death

Trypanosoma cruzi

• Kissing bug

• Bug lives in the cracks and crevices of mud huts.

• Mexico, South America

• Damage to the nerves

• Chagas disease

• Mega colon, mega esophagus

Kinetoplast

Mitochondrial DNA

flagellum

Plasmodium

• Malaria

• Mosquito

• Chills, fever, vomiting

• Complex lifecycle

• Chloroquine

Algae

Store energy –form petroleum diatoms

Dinoflagellates

• Plankton – free floating

• Aquatic environments – oceans

• Alexandrium – neurotoxin

• Mollusks – clams – eat a large amount of dinoflagellates - toxin is concentrated in clams

• People eat these clams – paralytic shellfish poisoning

• Numbness of the mouth and lips

• Heat stable

• Ocean has a red tide

Helminths

• Worms• Multicellular• Eukaryotic• Animal kingdom• Do not have a well developed nervous system or

digestive system.• Do have a complex reproductive system.• Platyhelminthes (flatworms) and nematodes

(round worms)

Platyhelminthes

• Trematodes (flukes)• Cestodes (tapeworms)• Trematodes• Flat leaf like body• Hermaphroditic ( have both male and female

reproductive organs – testes and ovaries)• Intermediate host – immature worm (larvae),

asexual reproduction• Definitive host – mature worm (adult), sexual

reproduction

Paragonimus westermani

• Lung fluke

• Bronchioles of infected humans and other animals.

• 12 mm long ( lives for 4 to 5 years)

• Chest pain, cough

• Praziquantel

Cestodes

• Intestinal parasites

• Head – scolex

• Scolex – hooks and suckers – attachment to the host.

• Segmented body

• Segments – proglottids

• Hermaphroditic

Taenia saginata – beef tapeworm

• Adult – human intestinal tract

• Eggs are released in the feces

• Cattle –ingest

• Larvae – cysts in the muscles (cysticerci)

• Transmitted to humans – undercooked contaminated beef.

• Intestinal tract – scolex comes out – develops into an adult worm.

• 18 feet

• 25 years

• Presence of eggs in the feces

• Abdominal discomfort

• Niclosamide

Taenia solium

• Adult – infected humans (definitive host)

• Eggs – feces

• Ingested by pigs ( intermediate host)

• Larvae - cysts in the muscles

• Undercooked contaminated pork

• More dangerous – humans can also become intermediate hosts.

• Eggs can be ingested by humans

• Larvae form cysts in the muscles, brain

• Neurocysticercosis – “swiss cheese”

• Headache , convulsions, coma , death

• Poor sanitary practices

• Mexico, South America

Echinococcus granulosus

• Definitive host – dogs coyotes

• Eggs – feces

• Humans – poor sanitary practices

• Larvae – cysts – liver – lungs

• Cysts – hydatid cysts

• Humans – dead end – life cycle of the worm

Sheep herding population

Nematodes (roundworms)

• Dioecious – male and female worms.

• Enterobious vermicularis (pinworm)

• Intestine - female migrates to the anus

• Releases eggs – perianal area

• Itching in the area

• Mebendazole

Ascaris lumbricides

• Small intestine

• Feed on semidigested food

• eggs – feces

• Larvae – intestinal tract – migrate to the lungs – go back to the intestine – adult

• Obstruction of the intestinal tract

Necator americanus

• Intestinal tract

• Eggs –feces

• Larvae come out in the soil

• Penetrates the skin – intestinal tract

• Attaches to the intestinal wall – drink blood

• Anemia

• Prevention – wear shoes

Trichinella spiralis

• Undercooked encysted pork – larvae come out in the intestinal tract

• Female releases larvae

• Larvae form cysts in the muscles

• Diaphragm muscle

• Pigs – eating contaminated pork