CHAPTER 5: THE EUKARYOTES OF MICROBIOLOGY

schizogony

(multiple fission) -nucleus divides multiple times before cell divides -produce merozoites stored in structures called schizonts

Karyogamy

+ and - nuclei fuse and form diploid zygote

supergroups that contain protozoans of clinical significance

-ameobozoa -chromalveolata -excavata (most parasites)

Basidiomycota (basidiomycetes)

-club fungi (due to shape of sexual spores) -sexual spores - basidiospores (formed externally on a base pedestal called a basidium; basidium is club shaped) -important as decomposers and as food (mushrooms, bracket fungi) -yeast form - cryptococcus

beneficial nature of fungi

-decompose dead plant matter - recycle vital elements -symbiotic fungi (mycorrhizae) - help plants absorb minerals and water -food for humans (mushrooms) -produce foods - bread, citric acid, et. -produce drugs - antibiotics like penicillin

significance of fungi

-fermentation technology (source of commercial enzyme production and production of acids/chemicals) -cultivation as protein food alternative -food processing (beer, bread, wine, cheese) -agricultural/environmental and medicinal applications -production of bioactive compounds (antibiotics, chemotherapeutics) -genetically engineered yeast strains used to make proteins (Hep B vaccine) -health implications (infections/diseases: mycoses)

characteristics of fungi

-heterotrophic (decompose organic matter) -molds and fleshy fungi multicellular -yeasts unicellular -cell walls made of chitin -cell membranes have sterols called ergosterols -reproduce sexually and/or asexually

asexual reproduction phases of malaria

-in human (intermediate host) 1. sporozoite undergoes schizogony in liver to form merozoites 2. merozoites for a ring stage inside blood cells (used for ID) 3. red blood cells rupture and more merozoites are released along with cytokines that lead to symptoms (fever and chills) -some merozoites develop into male and female sexual forms (gametocytes)

Ascomycota (ascomycetes)

-largest phylum of fungi -molds w septate hyphae; some are yeasts -asexual spores (conidiospores - conidia) -sexual spores - ascospores (spores form within a saclike structure called ascus) ex: Aspergillus flavus ex: Penicillium notatum ex: Athletes foot, jock itch, and ringworm caused by other molds ex: Candidia albicans ex: Saccharomyces cerevisiae

molds and fleshy fungi

-made up of filaments called hyphae (hypha) -a mass of hyphae is called a mycelium -mycelia form the body (called thallus) -hyphae may or may not have cross-walls called septa (septum) -septate hyphae (contain septa - indiv. cells w nucleus) -coenocytic hyphae (no septa - long continuous cells)

dinoflagellates

-mainly marine organisms -important component of plankton -phototrophic/heterotrophic/mixotrophic -2 flagella that make them whirl -some have theca (cellulose plate outer covering) -dense pop = red tide (harmful algal bloom ex: Alexandrium - toxin causes paralytic shellfish poisoning

malaria in the world

-major cause of morbidity and mortality (threatens 3.4 billion ppl worldwide) -endemic regions are Africa, parts of Asia, South America -despite reduction measures, continues to cause long term morbidity; intellectual disabilities in children

protozoa structures

-plasma membrane (plasmalemma) -some have pellicle -some have ectoplasm and endoplasm -cytostome -cytoproct

supergroup amoebozoa

-protozoans that use amoeboid movement -use pseudopodia ex: Entamoeba histolytica ex: Naegleria fowleri slime molds

Zygomycota (zygomycetes)

-saprophytes (get nutrients from dead organic matter) -Coenocytic (non septate) hyphae -Rhizopus stolonifer - black bread mold -asexual spores - sporangiospores -sexual spores - zygospores (forms when nuclei of 2 similar cells fuse; large spore within a thick cell wall)

preventative and therapeutics for malaria

-vaccines making slow progress -presidents Malaria initiative started in '05 - Bill and Melinda Gates Foundation -Chloroquine and hydroxychloroquine

protozoa motility

-whip like flagella -hair like cilia -cytoplasmic extensions known as pseudopodia (false feet)

3 phases of sexual reproduction of fungi

1. plasmogamy 2. karyogamy 3. meiosis

3 informal groups of protists

1. protozoa 2. prophyta 3. fungus like

dimorphic fungi

2 forms of growth -grow either as mold or as a yeast -temp dependent - yeast like 37 deg C and mold like 25 deg C -dependent on CO2 concentration -mold like form produces hyphae -yeast like form reproduces by budding -helps to survive in diverse environments ex: Histoplasma capsulatum - histoplasmosis, a lung infection

Stramenophiles

Chromalveolata -golden algae -brown algae -diatoms

Heartworm

Dirofilaria immitis -in dogs and other animals -transmitted via mosquitoes -fatigue and cough; when left untreated, death may result

Pinworm infections

Enterobius vermicularis -most common -transmitted by inhalation or ingestion of eggs from food/drink or fingers -sleeplessness and itching around the anus, where the female worms lay their eggs during the night

2 major groups/phylum of parasitic helminths

Nematoda (roundworms) Platyhelminths (flatworms)

Parabasalia

animal endosymbionts -have basal bodies and modified mitochondria (kinetoplastids) ex: Trichomonas vaginalis

protozoa

animal like nonphotosynthetic motile organisms that are always unicellular -can inhabit both aquatic and terrestrial habitats -many are free living, some are parasitic or symbiotic

supergroup chromalveolata

apicomplexa ciliates diatoms and dinoflagellates (discussed w algae)

protozoa reproductive mechanisms

asexual and sexual

imperfect fungi

asexually only (via mitosis)

what microorganisms are most infectious disease caused by?

bacteria and viruses

pellicle

bands of protein just inside the membrane

asexual reproduction of protozoa

binary fission budding schizogony

monoecious

both male and female reproductive organs in same

yeasts

budding yeasts - reproduce asexually by forming buds (daughter cell) -sometimes the cells/buds stick together as a short chain of pseudohypha ex: Candida albicans

T brucei

causes African trypanosomiasis (African sleeping sickness) -transmitted via the bite of a tsetse fly

T. cruzi

causes American trypanosomiasis (Chagas disease) -transmitted by bite of insects called kissing bugs

Trichomonas vaginalis

causes the human sexually transmitted disease trichomoniasis

tapeworms

cestodes -segmented flatworms (tape-like); have suckers or hooks -body made up of segments called proglottids ex: Taenia solium

sexual spores

characterize the phyla of fungi -zygospores (in Zygomycota) -ascospores (in Ascomycota) -basidiospores (in Basidiomycota)

slime molds

classified as animals, fungi, and plants -divided into cellular and plasmodial

algal diversity

classified within the chromalveolata and archaeplastida -dinoflagellates (chromalveolata)

sexual reproduction of protozoa

complex life cycles syngamy - produce haploid gametes protist conjugation (ciliates) - different from bacterial conjugation - exchange gen material through contact

chitin

complex, polysaccharide, polymer of N-acetylglucosamine, NAG)

fungal diversity

comprised of 7 groups -some associated w plants 4 groups of medical importance: -Zygomycota -Ascomycota -Basidiomycota -Microsporidia

excystment

cyst to trophozoite

meiosis

diploid nucleus produces haploid nuclei (sexual spores)

ectoplasm and endoplasm

distinct layers of cytoplasm under the membrane

fungi

diverse group -macroscopic fungi (mushrooms or molds) -many unicellular yeasts and spores of macroscopic fungi are microscopic -more than 100,000 species -about 200 are pathogenic and can cause mycoses (illnesses caused by fungi)

dioecious

either male OR female reproductive organs

what is the target for antifungal drugs?

ergosterols

green algae

ex: Chlamydomonas ex: Chlorella and Acetabularia ex: Volvox ex: Ulva

Platyhelminths (flatworms)

flukes tapeworms medically important parasites

encystment

formation of cyst trophozoite to cyste

supergroup excavata

fornicata parabasalia euglenozoa

diatoms

fossilized remains are used to produce diatomaceous earth -Frustules - outer cell walls of crystalized silica (2 parts of the wall fit together like a petri dish)

archaeplastida

green algae, red algae, land plants

Plasmogamy

haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-)

Chlamydomonas

has a single, large chloroplast, 2 flagella and a stigma (eye spot)

protozoa nutrition

heterotrophic organisms -holozoic -saprozoic

sexual reproduction of malaria

in the gut of Anopheles mosquito -gametocytes fuse to form zygote -zygotes develop into sporozoites, continues cycle

Euglenozoa

include photosynthetic and nonphotosynthetic species -cells have 2 flagella, a pellicle, a stigma (eyespot), to sense light, and chloroplasts for photosynthesis -typically not pathogenic -includes the Trypanosomes which are pathogenic pathogens (tropical diseases spread by insect bites) ex: T. brucei ex: T. cruzi

parasitic helminths

included in microbiology due to the detection/ID microscopic eggs/larvae -half are parasitic and some human pathogens -complex reproductive cycles w several different life stages -more than one type of host -monoecious -dioecious

cellular slime molds

individual amoeboid cells -periodically aggregate into a mobile slug -fruiting body that produces haploid spores

protists

informal taxonomic term to classify microscopic, unicellular (primarily) euk organisms -informal bc the organisms it describes do not have a shared evolutionary origin

saprozoic

ingest via small, soluble food molecules

holozoic

ingest whole food particle via phagocytosis

apicomplexans

intra or extra cellular parasites -have an apical complex at one end (concentration of organelles, vacuoles, and microtubules) -have complex life cycles (infective sporozoite that undergoes schizogony to make many merozoites) ex: plasmodium (causes malaria) ex: toxoplama gondii (causes toxoplasmosis) - transmitted by cats; causes fetal infections and serious birth defects in pregnant women ex: cryptosporidum - cysts transmitted via feces (cause epidemic diarrhea when the cysts contaminate drinking water

Fornicata

lack mitochondria but have flagella ex: Giardia lamblia

plasmodial slime molds

large, multinucleate amoeboid cells -form reproductive stalks to produce spores that divide into gametes

Chlorella and Acetabularia

large, unicellular algae -size of these organisms challenges the idea that all cells are small

what age is mortality the highest for malaria?

less than 5 years old

reduction measures for malaria

mainly aimed at reducing mosquito population -insecticide treated bed nets -spraying of pesticides

plankton

microorganisms that drift or float in water -zooplankton -pytoplankton

asexual reproduction in fungi

mitosis, fragmentation of hyphae formation of asexual spores by mitosis

Nematoda (roundworms)

more than 15,000 species (several are human parasites) -unsegmented, full digestive system -common intestinal parasites -dioecious reproductive system ex: pinworm (Enterobius vermicularis) infections ex: Heartworm (Dirofilaria immitis)

zooplankton

motile and nonphotosynthetic

brown algae

multicellular marine seaweeds -some can be extremely large, such as the giant kelp -have leaf-like blades and stalks (holdfasts - used to attach to substrate; not true leaves, stems or roots)

algae

not a taxonomic group - grouped informally w protists (unicellular or multicellular) -autotrophic (use sunlight for energy and CO2 as carbon source - responsible for 70% of O2 and organic matter in aquatic env.) -source of solidifying agents (lab and food - agar, agarose, carrageenan) -not typically pathogenic, but some produce toxins (harmful algal blooms (HABs); impairment of liver and CNS function of aquatic animals and humans -some algae (seaweeds) - macroscopic and may be confused w plants -can also be confused w cyanobacteria (prok)

Naegleria fowleri

notorious brain eating amoeba found in warm, fresh water causes primary amoebic meningoencephalitis (PAM) fatal infections sometimes

pytoplankton

photosynthetic

other informal terms for protists

plankton

prophyta

plant like -algae; photosynthetic organisms that can be unicellular or multicellular

malaria

plasmodium falciparum - causative agent of the most severe form of malaria -asexual and sexual phases

taxonomy of protists

polyphyletic group -lack shared evolutionary origin -scattered in many different taxonomic groups within eukarya

Aspergillus flavus

produces aflatoxin that is both a toxin and the most potent known natural carcinogen

Penicillium notatum

produces the antibiotic penicillin

kinetoplastids

protozoa modified mitochondria

contractile vacuoles

protozoa used to move water out of the cell

cytoproct

protozoa excretion exocytosis via this

cytostome

protozoa ingestion phagocytosis via this

perfect fungi

reproduce sexually and asexually

asexual spores

specialized cells -for survival, reproduction, and dispersal -used in ID and classification

Taenia solium

taeniasis or cysticercosis -transmitted via ingestion of raw/undercooked pork containing tapeworm cysts -asymptomatic or several neurological impacts

Entamoeba histolytica

transmitted by cysts in feces amoebic dysentery

flukes

trematodes -nonsegmented flatworms; have an oral sucker (liver flukes, intestinal flukes, oriental lung flukes) -Schistosomiasis (Schistosoma) - found in freshwater snails, contact w contaminated water leads to multiorgan infections (anemia, malnutrition, fever, abdominal pain, fluid buildup, or death)

2 lifecycle phases for most protozoa

trophozoite - feeding and growing form (feeds on bacteria and small particle nutrients) cyst - dormant, protective form (cell w a protective wall)

Saccharomyces cerevisiae (bakers yeast)

used for brewing beer

Candida albicans

vaginal yeast infections, oral thrush, and candidiasis of the skin Ascomycota

Giardia lamblia

widespread pathogen that causes diarrheal illness -spread through cysts from feces that contaminate water supplies