Protozoa

Biological Sciences 310 with Sloan at University of Alabama - Tuscaloosa

About this deck

By: Allison Maddox
Textbook:

Enhanced College Physics (with PhysicsNOW)
Created: 2012-05-01
Size: 80 flashcards
Views: 32

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Protozoa General Characteristics

-unicellular, usually motile, eukaryotic chemotheterotrophs

-carry out functions w/o specialized cells and tissue; use specialized organelles

-most are parasitic

-most are obligate aerobes

Protozoa size

vary from about 3μm to up to 5 mm in diameter

some fossils up to 3 inchest

Protozoa habitats

wide variety

most live in freshwater or marine

terrestrials found in moist soils or decaying organic matter

Optimal temperatures for Protozoas

Usually between 10º and 25ºC, but some can grow at temperatures up to 50ºC and many can survive freezing

Pellicle

tough outer compound membrane

unique to protozoa and a few algae

may be rigid or flexible

Shells, tests or lorica

some protozoa

rigid external structures made of calcium carbonate, silica or chitin

Cysts

Under adverse conditions (nutrient depletion, desiccation, presence of toxic compounds)

Thick outer coverings of keratin-like protein, cellulose or other polysaccharides

Dormant structures

Encystation (Encystment)

Process of producing dormant structures

trophozoite

Reproducing form of the organism

2 Types of Cytoplasm

Ectoplasm and Endoplasm

Ectoplasm

Cytoplasm just under the cell membrane

Clear and gel-like

Endoplasm

-inner cytoplasm

-granular and fluid

-contains most of the internal organelles

Contractile Vacuoles (Water-expelling vacuoles)

-All freshwater protozoa

-osmoregulation

-not marine protozoa

Pseudopodia, Flagella or Cilia

Motile by means of these

-Flagella and cilia identical except cilia are shorter, both are anchored to the ectoplasm region

Kinetosomes, Blepharoplasts or Basal bodies

Anchor the cilia or flagella to the ectoplasm region

Kinetodesmata (neurofibrils)

Ciliated protozoa structures that connect kinestosomes and help coordinate ciliary movement

Extrusomes (trichocysts, toxicysts, haptocysts)

Some cilitates and a few flagellates

-proteinaceous barbs that can be forcibly ejected

-used for protection, predation and/or anchoring of the organism

Resting extrusomes

lie just under the cell membrane

sarcodines

amebas and their close relatives

Holozoic

Phagotrophic

-sarcodines, some flagellates and most ciliates

Holphytic

osmotrophic

-some flagellates, a few ciliates

Reproduction

Most asexual

-some budding, schizogony, syngamy and conjugation

Asexual Reproduction

Most protozoa

process of binary fission in which the nucleus divides mitotically, followed by cytokinesis

Schizogony

Multiple fission

single cell divides to form a multitude of daughter cells

2 Types of Sexual Reproduction

Syngamy and Conjugation

Syngamy

Sexual Reproduction

-foudn in apicomplexans and some flagellates and sarcodines

-fusion of specialized gametes to form a zygote

Conjugation

-Sexual Reproduction

-ciliates

-bidirectional exchange of genetic information between 2 organisms by a cytoplasmic bridge formed by fusion of their pellicles

Importance

-components in food chains and webs

-decomposers

-research organisms, cellular differentiation

Classification

Kingdom: Protista

Subkingdom: Protozoa

-7 phyla based on mechanism of locomotion, types of nuclei and mode of reproduction

Phylum Sarcomastigophora

-single type of nucleus

-use pseudopodia, flagella

-asexual reproduction by binary fission

-sexual reproduction, if present, by syngamy

Subphylum Sarcodina

-Amebas and their relatives

-Move and feed by pseudopodia

-Most are marine

Lobopodia

Broad, blunt, relatively short pseudopodia with rounded tips

Well-defined ectoplasm and endoplasm

Used for motility and food gathering

Filopodia

-Extremely slender pseudopodia that taper to a fine point

-May branch but don't form a network

-Used for movement and food gathering

Reticulopodia (Myxopodia or Rhizopodia)

-Slender projections that branch and anastomose (fuse) to form a complex network

-used as a "net" to trap food but not very effective for motility

Axopodia

-very slender with an axial microfilament

-Radiate out from the surface of the sarcodine in a uniform manner

-used primarily to gather food but do allow for slow motility

Foraminiferans

-Have calcium carbonate tests

-Live and ooze on the ocean floor

-massive deposits of their test become sedimentary rock (limestone) and later give rise to formations such as the White Cliffs of Dover

-important aids to geologists for oil-bearing strata during oil drilling

Radiolarians

-planktonic sarcodines

-usually with silicate tests

-give rise to sedimentary rock (radiolarian chert) when their tests settle to the bottom of the ocean after death

3 Diseases of Sarcodines

-Intestinal diseases

-Meningoencephalitis

-Inflammation of the cornea (keratitis)

Amebiasis (amebic dysentery)

-Entamoeba histolytica

-Ingesting cysts in fecally contaminated food or whater

-worldwide, warmer climates, poor sanitation

2 Forms of Amebiasis

Acute amebic dysentary

Chronic amebiasis

Acute Amebic Dysentery

-Invades the mucosa of the alrge intestine and causes ulceration and bloody stool, nausea and vomiting

-shed mostly trophozoites and aren't as contagious

-Rarely: enters blood and spreads to liver, lungs and brain; fatal if not treated promptly

Chronic Amebiasis

-No bloody stool

-Shed mostly cysts, more dangerous (contagious)

Entamoeba coli

common nonpathogenic ameba

-larger contains only bacteria in food vacuoles

-cysts have 8 nuclei, 1-2 chromatoid bars with jagged ends

Entamoeba histolytica

-smaller, contains RBCs in its food vacuoles

-cysts have 4 nuclei and 1-2 chromatoid bars that are clusters of ribosomes with rounded ends

Amebic meningoecephalitis

-Naegleria fowleri

-freshwater and moist soil

-gets in nose: move along olfactory nerves to brain

-almost always fatal

-Unusual lifecycle w/both amebic and flagellated forms; will encyst in dry conditions

-flagella form can move 100x faster

Amebic keratisis

-Acanthamoeba spp.

-Progressive, ulcerative inflammation of the cornea

-enters corneal tissue through small abrasions on the surface of the eye, can result in blindness

-Rarely spreads to brain, causing meningoencephalitis and death

-Soft contact lens wearers

Subphylum Mastigophora

-flagellated protozoa

-Longitudinal binary fission

-Sexual reproduction rare

-Flagella are membrane bound cyclinders about 0.2 μm in diameter and 100-200μm long, complex of 9 pairs of microtubules surrounding 2 central tubules; move by undulating, can push/pull along

-most are free living in freshwater, some marine, few important man/animal parasites

Giardiasis

-disease by flagellate

-backpacker's diarrhea

-Giardia lamblia

-cyst forms must be ingested

-excyts and trophozoite attaches to intestinal mucosa by ventral sucking disk and aborbs nutrients

-prolonged diarrhea, malaise and cramps

-worldwide; 10% US; common in daycare centers; in mammals

-cysts can survive for months, esp. cool water; normal chlorination doesn't kill cysts, slow sand filtration to remove cysts, but may fail on occasion

Trichomoniasis

-disease by flagellate

-Trichomonas vaginalis

-STD

-Women- causes vaginitis

-Men- causes urethritis and prostatits

-Inching, pain, urinary frequency, pain and discharge

-Cysts aren't formed, but can survive outside body for a time under moist conditions

Trypanosomiases

-disease by flagellate

-caused by Trypanosoma

-2 types

2 Types of Trpanosomiasis

1. American trypanomiasis (Chagas disease)

2. African trypanosomiasis (African sleeping sickness)

American trypanosomiasis (Chagas Disease)

-disease by flagellate

-T. cruzi

-Zoonotic infection passed by "kissing bugs" (bite around lips while sleeping); sheds flagellate in its feces, scratch bite and contaminate wound

-replicates as intracellular parasite, tissues of heart, colon, esophagus

-fever, malaise, aches, nausea, diarrhea, vomiting, large spleen and liver, swollen

-period of remission (yrs) chronic phase entered, digestive and swallowing problems

No vaccine

African trypanosomiasis (African Sleeping Sickness)

-Flagellate disease

- T. brucei gambiense and rhodesiense

-bite of tsetse fly; animal resivoirs

-fever, joint pain, swollen lymph glands and spleen

-enters CNS; meningoencephalitis, seizures, coma, death (after 6 months)

-100 % fatal w/o treatment

-NO vaccine but effective drugs at first sign of infection

Phylum Ciliophora

-Use cilia for moltility and feeding

-2 types of nuclea

-cilia similar to flagella but shorter; beat in coordinated manner

-Asexual reproduction by transverse binary fission

-Sexual Reproduction by conjugation

-Largest and most evolved group (8000 sp)

-Most free living in freshwater; one man disease

2 types of Nuclei in Ciliophora

Polyploid macronucelus

Diploid Micronucleus

Polyploid Macronucleua

directs all RNA synthesis in the cell, responsible for controlling cell's metabolism

Diploid Micronuclei

-Sexual reproduction and production of the macronucleus

Balantidiasis

-Ciliary dysentery

-Balantidium coli

-zoonotic disease; mostly hogs

-must ingest the cyst stage of the organism

-excysts in large intestine and burrows into the intestinal mucosa

-symptoms similar to amebic dysentery (nausea, vomiting, and bloody stool)

Phylum Apicomplexa

-Obligate parasites of vertebrates w/complex life cycles (alternation between sexual and asexual stages in 2 hosts)

-3 genera of medical importance

Schizogony

Asexual part of cycle in Apicomplexa

-intermediate host

-process of multiple division; one cell undergoes many rapid mitotic nucelar division with the formation of many uninucleat cells (merozoites tachyzoites)

Sporogony

-Sexual part of Apicomplexa life cycle

-definitive host

-fertilization of larger female gamete by smaller motile male gamete

Malaria

-caused by 4 sp of Plasmodium

-Monkeys may be reservoir

-host are female mosquitos (Anopheles)

-One of the worlds biggest health problems

3 Types of Malarial Infections

1. Benign tertian malaria

2. Benign Quartan Malaria

3. Malignant tertian malaria

Benign tertian Malaria

-P. vivax & P. ovale

-48-hr cycle of chills & fever

-mild form, but parasites have exoerythrocytic cycle in the liver, leading to recurrences of the disease if treatment doesn't kill the parasites in the liver

Benign Quartan Malaria

-P. malariae

-72-hr cycle of chills & fever

-more serious form

Malignant tertian malaria

-P. falciparum

-life-threatening form, much less synchronous

-fewer chills, prolonged high fever (48hr cycle)

-Extensive swelling of brain, lungs and spleen

-Clogging of small veins and capillaries with infected RBCs

-dark colored urine, rapid kidney failure and death

Hemogloburia

-Dark colored urine

-Malignant Tertian Malaria

-leads to rapid kidney failure and death

Blackwater Fever

-Dark colored urine (hemoglobinuria)

-Malignant tertian malaria

Control of Malaria

1. Kill Mosquito vector (eliminate standing water, cover water with oil, use insecticides)

2. take prophylactic drugs, use repellents and nets

3. Chemotheraphy (quinines, derivatives of quinine

4. Vaccines

Bt-toxin

Insecticide used for Malaria

available in mosquito dunk and in powder form

only harmful to insects and is biodegradable

Quinine

-Oldest Malaria treatment

-Alkaloid extracted form the bark of Cinchona tree

-Kills merozoites but not exoerythrocytic stages (have relapses)

Quinine Derivatives

-non likely truly cure the disease

-drug-resistant strains developed

Artemisinin

-extract from chinese wormwood plant

-most effective

-plant in short supply, too expensive

RBC Disorders and Malaria

Some inherited disorders of RBCs are lethar in homozygous individuals but protect heterozygous individuals form the malarial parasite

Such genetic disorders occur at high frequencies in populations where malaria is endemic

Sickle Cell Anemia

Mutant hemoglobin molecule has 2 AA difference causing a mutant protein molecule to aggregate & form structures at low [O₂] or low pH, sickling of RBCs; block capillaries and cause tissue death

Heterozygous RBCs infected sickle more easily and kill the parasite

Possible Mechanisms for Killing the Malaria Parasite

1. Sickled cells are phagocytized & killed by macrophages in the spleen.

2. Hemoglobin forms bundles, that may disrupt the parasite's membrane and kill it

3. Sickled cells leak potassium, killing the parasite. They'll survive in RBCs that are cultured in a medium with high levels of potassium.

Toxoplasmosis

-Apicomplexa disease

-Toxoplasma gondii

-worldwide, 50-90% infected at some point

-infects intestinal epithelial cells in cats and reproduce there

-some develop into gametocytes once shed by cat droppings; then develop into oocysts

-Oocysts ingested, release sporozoites, develop into tachyzoites and infect tissues, convert to bradyzoites in pseudocysts in tissues, lasts for life

Bradyzoites

Slowly reproducing forms of toxoplasmosis

Cryptosporidiosis

-Apicomplexa disease

-Cryptosporidium parvum

-worldwide; life cycle similar to Toxoplasma except cats aren't only host

-has become major human health concern

-No drugs are useful

-Prevention difficult: resistant to chlorine and too small to be removed by filtration

-Acid-fast positive

About this deck

By: Allison Maddox
Textbook:

Enhanced College Physics (with PhysicsNOW)
Created: 2012-05-01
Size: 80 flashcards
Views: 32

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy