microbiology lecture chapter 12

Meiosis

Meiosis. The diploid nucleus gives rise to haploid nuclei (sexual spores) some of which may be genetic recombinant

Medically Important Divisions of Fungi

Zygomycota Ascomycota Basidiomycota Anamorphs

Anamorphs (major divisions of the fungi)

(Deuteromycota) - the "imperfect fungi," only asexual spores (usually conidiospores), have septate hyphae

pseudohypha

(found in some budding yeasts) -short chain of buds that is unable to detach -Candida albicans requires to invade deeper epithelial tissue

cestodes (tapeworms)

*Intestinal parasites *Head is called Scolex. *Scolex has suckers for attachement. Some have hooks *Completely lack digestive system. Food absorbed through cuticle *Body consists of segments called proglottids *Each proglottid has both male and female reproductive organs *New proglottids are produced in the neck region and marure toward the end. *Mature proglottid is actually bag of eggs. Each egg can infect intermediate host

structure of molds: hypha

-A long filament of cells in fungi -Each fragment of hypha is capable of growth

structure of molds: mycelium

-A mass of long filaments of cells that branch and intertwine

insect vectors

-A number of insects transmit disease from one host to another -The tse tse fly transmits African trypanosomiasis (sleeping sickness) -The rat flea transmits bubonic plague, which decimated European and Asian populations during the Middle Ages

Subcutaneous Mycosis

-Beneath the skin, spores or mycelial fragement - wound. -By saprophytic fungi (soil, vegetation) e.g., Sporotrichosis

Systemic Mycosis

-Deep within the body through inhalation of spore (soil) -Not contagious e.g., Histoplasmosis, Coccidioidomycosis

liver fluke

It is a human liver fluke that is found mainly in the common bile duct and gall bladder. First intermediate host is a special snail and second intermediate host is a fish

Karyogamy

Karyogamy. The (+) and (-) nuclei fuse to form a diploid zygote nucleus.

major divisions of protozoa

1. apicomplexa 2. ciliophora 3. euglenozoa

divisions of protozoa

1. archaeozoa 2. microsporidia 3. amoebozoa

fungal life cycle asexual reproduction

1. hypha produces conidiophore 2. conidia are released from conidiophore 3. conidium germinates to produce hypae 4. vegetative mycelium grows

parasitic helminths phyla

1. phylum platyhelminthes (flatworms) a) class trematodes (flukes) b) class cestodes (tapeworms) 2. phylum nematoda (roundworms)

fungi

Kingdom: Fungi Nutritional Type: Chemoheterotroph Multicellularity: All, except yeasts Cellular Arrangement: Unicellular, filamentous, fleshy Food Acquisition Method: Absorptive Characteristic Features: Sexual and asexual spores Embryo Formation: None

stipes of algae

stemlike and often hollow

thallus of algae

the body

5 phyla of algae

phaeuphyta: brown algae rhodophyta: red algae chlorophyta: green algae bacillariophyta: diatoms dinoflagellata: dinoflagellates

Blastoconidia

b) Blastoconidia is another type of conidia that consists of buds coming off the parent cell. Some yeasts produce this type of conidia, like Candida albicans.

basidiospore

-Formed externally on a pedestal(basidium) -sexual spore

acospore

-Formed in a sac (ascus) -sexual spore

fungal infection

-Fungal infection is called mycosis -Generally chronic (long-lasting) -Difficult to treat because of similarities of animal and fungal cells

zygospore

-Fusion of haploid cells produces one zygospore -sexual spore

opportunistic (fungal infection)

-Generally harmless fungi become pathogenic -e.g., Pneumocystis - pathogenic in AIDS patients ** Stachybotrys - cause fatal pulomonary hemorrhage in infants ** also Mucormycosis, Aspergillosis, Candidiasis

Taenia solium - the pork tapeworm

-Humans are the definitive host, swine are the intermediate hosts -Proglottids leave the human body in feces and contaminates will fed to pigs -Humans acquire the disease by eating raw pork -Eggs eaten by humans can hatch and larvae encyst in the brain and other parts causing cysticercosis

helminths

-Kingdom: Animalia -Nutritional Type: Chemoheterotroph -Multicellularity: All -Cellular Arrangement: Tissues and organs -Food Acquisition Method: Ingestive; absorptive -Characteristic Features: Elaborate life cycles -Embryo Formation: All

protozoa

-Kingdom: Protist -Nutritional Type: Chemoheterotroph -Multicellularity: None -Cellular Arrangement: Unicellular -Food Acquisition Method: Absorptive; ingestive -Characteristic Features: Motility; some form cysts -Embryo Formation: None

algae

-Kingdom: Protist -Nutritional Type: Mainly Photoautotroph -Multicellularity: Some -Cellular Arrangement: Unicellular, colonial, filamentous, lack tissues (roots, stems, and leaves) of plants. -Food Acquisition Method: Diffusion -Characteristic Features: Pigments -Embryo Formation: None

helminths life cycle

-Life cycle is complex as each larval stage needs a specific host. -Adult Helminths may be dioecious (have male and female) or monoecious or hermaphroditic (one animal has both types of reproductive organs). -Some hermaphroditic helminths do cross fertilization but other do self fertilization.

Cutaneous Mycosis (Dermatomycosis)

-On epidermis, hair, nails. Secrete Keratinase -Transmitted from human-to-human, animal-to-human, contact

characteristics of algae

-Relatively simple eukaryotic photoautotroph that lack the tissues (roots, stems, and leaves) of plants. -Oomycotes (fungal-like algae) are chemoheterotrophs -Some algae are unicellular, others are filamentous (form chains of cells); and a few have thalli. -A few algae are responsible for food poisonings. -All algae can reproduce asexually. Fragments of thalli & filaments are capable to form new thalli and fragments -Sexual reproduction also occurs in algae.

structure of molds: thallus

-The entire vegetative structure of body of a fungus -Consists of long filaments of cells (hyphae) joined together

asexual spores

-The most common method of asexual reproduction in fungi is by means of spores -Fungal spores exhibit a wide variability in coloration, surface sculpturing, size, shape, number of cells, and the manner in which they are borne on the mycelium -All, are most, of these features are used for identification of genera and species -Asexual spores are formed by the hyphae of one organism. They are produced by individual fungus through mitosis and subsequent cell divisions.

blood fluke

-The motile larval stage (top photo) penetrates the skin of people bathing in stagnant water pools -The adult parasite invades the liver and produces disease -Tell-tale signs are a swollen abdomen and the presence of microscopic eggs in the feces (bottom photo)

characteristics of helminths

-These are multicellular eukaryotic free living or parasitic animals. Parasitic species may have the following adaptation. -May lack a digestive system - nutrients are absorbed -Reduced nervous system -Completely lacking or reduced organs for locomotion (movement) -Complex reproduction system to produce a large number of eggs

Dinoflagellata - dinoflagellates

-Unicellular algae collectively called plankton (free floating) Some produce neurotoxins. -Paralytic shellfish poisoning - caused by saxitoxin (a neurotoxin) produced by genus Alexandrium that forms red tide in ocean. Humans contract that disease when they eat mollusks feeding on these dinoflagellates. -Ciguatera is caused by Gambierdiscus toxicus by eating large fish.

Bacillariophyta - Diatoms

-Unicellular or filamentous with cell wall of pectin and a layer of silica. -Domoic acid intoxication (cause diarrhea and memory loss) is caused by eating mussels feeding on diatoms

fungal spores

-Unlike a bacterial spore, fungal spore is a true reproductive spore. -They are less tolerant to dry or hot environment than the bacterial spores. -Fungal spores are formed from aerial hyphae. -Fungal spore can be either Asexual or Sexual

amoebozoa

-also called amoebas, move by blunt projections called pseudopods; pathogens -Entamoeba, Acanthamoeba

trematodes

-flukes -flat leaf-shape bodies -have ventral sucker and an oral sucker (to hold itself on one place) -have cuticle (nonliving outer covering). hermaphrodites 1. liver fluke 2. blood fluke 3. lung fluke

reproductive or aerial hypha

-portion of hypha concerned with reproduction -projects above the surface -often bear reproductive spores

vegetative hypha

-portion of hypha that obtains nutrients

zygomycota

-sexual spores are thick walled resting spores called zygospores (asexual spores are borne internally in a sporangium) -the "conjugation fungi" coencytic hypae

basidiomycota

-the "club fungi," include mushrooms -have septate hyphae -sexual spores borne externally on club shaped structure called basidium (usually no asexual spores)

ascomycota

-the "sac fungi" septate hyphe -sexual spores borne internally in a sac called an ascus (asexual spores are borne externally as conidia)

septate hypha

-they contain cross-walls called septa -units are uninucleate

coenocytic hypha

-they do not contain septa -appear continuous with many nuclei

microsporidia

-unusual eukaryotes without mitochondria or microtubules; pathogen -Nosema (obligate intracellular parasite)

archaeozoa

-unusual eukaryotes without mitochondria, usually two or more front-end flagella; pathogens -Giardia, Trichomonas

fungal life cycle sexual reproduction

4. vegetative mycelium grows 5. plasogamy 6. karyogamy 7. meiosis then mitosis 8. ascus opens to release ascospores 9. ascospore germinates to produce hypae

Chlamydospores

Chlamydospores are thick walled spores formed by rounding and enlargement within a hyphal segment. Example is Candida albicans

Conidiospore

Conidiospore or conidium is a unicellular or multicellular spore that is not enclosed in a sac. Conidia are produced in a chain at the end of a conidiophore. Example is Aspergillus.

Superficial Mycosis

Hair shafts, superficial epidermis

nematodes

Have a complete digestive system with mouth, intestine and anus Most are dioecious with sexual dimorphism. Smaller males with one or two hardened spicules on the posterior end to guide the sperms to the female's genital pore. Some species are free living and others are parasites of plants and animals. Some spend their life cycle in one host (Enterobius vermicularis) -Divided into two groups. 1. Group having infective eggs 2. Group having infective larva

Plasmogamy

Plasmogamy. A haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient cell (-).

sexual spore

Sexual spore result from sexual reproduction, consisting of three phases: 1) Plasmogamy 2) Karyogamy 3) Meiosis

Sporangiospores

Sporangiospores are formed within a sporangium, or sac, at the end of an aerial hypha called a sporangiophore. Example is Rhizopus.

asexual spore types

These are of different types 1) Conidiospore a) Arthrospore b) Blastoconidia 2) Chlamydospores 3) Sporangiospores Clinical identification of fungi is based on microscopic examination of asexual spores.

characteristics of fungi

Three types; yeasts, molds, and mushrooms All are eukaryotic Aerobic or facultatively anaerobic (a few are anaerobic) Out of 100,000 fungal species, only about 200 are pathogenic Reproduce by means of spores, usually wind - desseminated Both sexual (meiotic) and asexual (mitotic) spores may be produced, depending on the species and condition Typically non-motile, although a few (e.g., Chytrids) have a motile phase Fungi have an alternation of generation

Arthroconidia

a) Arthroconidia is a type of conidia, formed by the fragment of a septate hypha into single, slightly thickened cells. Example is Coccidioides immitis

holdfast of algae

branches of thalli which anchor the seaweeds to a rock

ciliophora

ciliary motion; pathogen - balantidium coli

euglenozoa

flagella; pathogen - trypanosoma

pneumatocyst

gas filled bladder found in some algae that acts as a float

blades of algae

leaflike

apicomplexa

non motile, intracellular parasites, ex plasmodium (complex life cycle)