Protozoa

Question 0

Protozoa Habitats

Answer 0

Primarily in moist habitats, most are free living in aquatic environment, terrestrial Protozoa usually found in decaying organic matter and soil, some parasitic in plants and animals.

Question 1

Protozoa characteristics

Answer 1

Unicellular, usually motile, lack cell walls, chemoorganoheterotrophs.

Question 2

Protozoa importance

Answer 2

Important link in food chains and food webs. Make up large part of plankton in aquatic habitats. In research model organisms because have same pathways as multicellular eukaryotes. Causative agents of some important diseases in humans and other animals.

Question 3

Protozoan groups

Answer 3

Amoeba, Sporozoa, Ciliates, Flagellates

Question 4

Protozoan cell features

Answer 4

Similar to cell of eukaryotes with some unique features. Pellicle ( plasma membrane and structures immediately beneath it).Macronucleus (trophic activities and regeneration), Micronucleus (diploid , recombination, regeneration of Macronucleus ). Have differentiated vacuoles

Question 5

Vacuoles type

Answer 5

Contractile vacuoles : osmoregulatory, expel water
Phagocytic vacuoles: site of food digestion
Secretory vacuoles: contain enzymes for specific functions(e.g. Excystation)

Question 6

Protozoa Nutrition

Answer 6

Chemoheterotrophic
Two types of nutrition: 1- Holozoic nutrition (nutrients acquire by phagocytosis) Cytostome (used by some ciliates for phagocytosis) 2- Saprozoic nutrition: nutrients acquired by pinocytosis, diffusion, or carrier-mediated transport

Question 7

Encystation

Answer 7

Formation of a cyst

Question 8

Excystation

Answer 8

Escape of vegetative form from cyst. Excystation often triggered by entry into new host.

Question 9

Trophozoite

Answer 9

Vegetative form released by parasitic species

Question 10

Protozoan Locomotory Organelles

Answer 10

Cilia, Flagella, Pseudopodia

Question 11

Protozoa Reproduction

Answer 11

Asexual : binary fission, mitosis followed by cytokinesis

Sexual : conjugation, exchange of game tic nuclei between paired protozoan of opposite mating types.

Question 12

Kinetoplast

Answer 12

Mitochondrial DNA

Question 13

Trypanosomes

Answer 13

Hemoflagellate, important blood pathogens transmitted by biting insects. E.g.
T.cruzi “Chagas disease”
T.gambiense “African sleeping sickness”
Giardia lamblia : giardiasis, gastrointestinal disorder
Trichomonas vaginalis : Trichomoniasis, sexually transmitted disease

Question 14

Sarcodines

Answer 14

Some pathogenic Amoeba

Question 15

Entamoeba histolytica

Answer 15

Amoebic dysentery

Question 16

Naegleria Fowlerii

Answer 16

Causes primary amoebic meningo-encephalopathy

Question 17

Acanthamoeba polyphaga

Answer 17

Causes Acanthamoeba keratitis corneal infection

Question 18

Apicomplexa

Answer 18

Lack locomotor organelles, except for make gametes and zygotes.
All have apical complex, arrangement fibrils, tubules, vacuoles, and other organelles at one end of cell.

Question 19

Conoid

Answer 19

Spirally arranged fibers in Apicomplexa

Question 20

Apical complex

Answer 20

Subpellicular tubule

Question 21

Rhoptry

Answer 21

Contains materials that are secreted and aid in penetration of host cell in Apicomplexa

Question 22

Apicomplexan Life cycle

Answer 22

Two different hosts , usually mammal and mosquito
Involves both asexual and sexual phases.
Schizogony: asexual phase, rapid series of mitotic events producing infective organisms.
Oocyst: produced during sexual phase, thick-walled, diploid structure, undergoes meiosis to produce haploid spores

Question 23

Plasmodium life cycle

Answer 23

Sporozoites inject into host during the blood meal, invade liver cells and undergo schizogony, liver cells rupture and release numerous merozoites into blood, into erythrocytes some develop into gametocytes, mosquito ingest gametocytes during blood meal, gametocytes become gametes that fuse to form zygote, zygote become oocyst in gut wall, oocyst form sporozoites, rupture and sporozoites migrate into salivary glands of mosquito.

Question 24

Important Sporozoan genera

Answer 24

Plasmodium vivax, P. falciparum, P.malariae, P. ovale ( causative agent of mosquito borne malaria), Cryptosporidium parvuum- cryptosporidiosis, Toxoplasma gondii- toxoplasmosis

Question 25

Microspora

Answer 25

Abundant and pathogenic in insects, potential use as pest control
Some genera implicated in diseases in immunosuppressed and AIDS patients.

Question 26

Nosema bombycis

Answer 26

Microspora causes Pebrine disease in silkworms

Question 27

Ciliophora food processing

Answer 27

Enters Cytostome, phagocytic vacuole, fuse with lysosomes, digestion occurs, vacuole fuses with Cytoproct, waste emptied outside

Question 28

Pathogenic Ciliates

Answer 28

Balantidium coli : intestine of humans and other mammals, cause dysentery.
Ichthyophthirius : “ick” disease in freshwater fish

Question 29

Pathogenic protozoa in the Sarcodina class

Answer 29

Entamoeba histolytica, causes a disease called amoebic dysentery. This is a serious intestinal disease accompanied by deep bleeding ulcers and extensive fluid loss. It is transmitted by contaminated food and water, and it occurs primarily in tropical regions.

Question 30

4. What are some of the distinguishing characteristics of the class Mastigophora?

Answer 30

Mastigophora move by means of whiplike flagella. They reproduce by binary fission in the longitudinal plane and obtain their food by ingesting large particles and absorbing small particles. The well-known organism Euglena is in the Mastigophora class. The organism possesses chlorophyll within cytoplasmic bodies called chloroplasts. The chlorophyll allows the organism to trap sunlight energy and convert it to energy in carbohydrates during the process of photosynthesis. Euglena species also have the enzyme systems, allowing them to digest carbohydrates and release the energy by cellular respiration.

Question 31

Pathogenic species belong to the class Mastigophora

Answer 31

There are several human pathogens found in the class Mastigophora. One example is Trypanosoma brucei, the cause of African sleeping sickness. Another pathogen is Giardia lamblia, the cause of giardiasis, an intestinal disease accompanied by severe diarrhea. Also in the group is Trichomonas vaginalis, the cause of trichomoniasis, a sexually transmitted disease in humans. All these organisms move by means of flagella.

Question 32

Do any members of the Mastigophora class form cysts?

Answer 32

Certain species of the Mastigophora form cysts, the highly resistant structures that encourage survival in the external environment. For instance, the pathogen Giardia lamblia forms cysts and remains alive outside the body in contaminated water until it reenters the body. Trichomonas vaginalis forms no cysts and must pass from individual to individual to remain alive.

Question 33

well-known member of the Ciliophora class

Answer 33

most recognized member of the Ciliophora class is the organism Paramecium. This slipper-shaped organism is surrounded by cilia that beat synchronously and allow the organism to move in several directions through fluids. Macro and micro nucleus

Question 34

Pathogens in the class Ciliophora

Answer 34

Balantidium coli. This organism inhabits the human intestinal tract where it may cause mild to severe diarrhea. Contaminated water and food, especially pork, transmit the organism among humans

Question 35

characteristic features of protozoa in the class Sporozoa

Answer 35

Members of the class Sporozoa (Apicomplexa) have no organs for motion in the adult form, and therefore they differ from other protozoal species. The members also have complex life cycles involving both asexual and sexual stages, often occurring in different hosts. Various stages in the life cycle may include forms known as merozoites, sporozoites, and oocysts.

Question 36

malaria classified in the Sporozoa group

Answer 36

Malaria is caused by several species of Plasmodium classified as Sporozoa. The protozoa are transmitted among humans by the female Anopheles mosquito. They undergo their life cycles in human red blood cells and destroy the latter, causing chills and extremely high fever in alternating sequence.

Question 37

other important pathogens classified as Sporozoa

Answer 37

Toxoplasma gondii. This organism causes toxoplasmosis, a disease of white blood cells transmitted to humans by domestic housecats. In AIDS patients, toxoplasmosis is an important opportunistic disease. Another important pathogen is Cryptosporidium coccidi. In AIDS patients, this organism induces extensive diarrhea that can lead to dehydration and emaciation.

Question 38

Pneumocystis carinii classified in the Sporozoa?

Answer 38

It lives in the lungs of persons with AIDS, where it induces a severe form of pneumonia that can be fatal. Indeed, fully half the deaths associated with AIDS are due to disease caused by Pneumocystis carinii.