Flashcards in 3 Microbiology: Protozoa Deck (83)
What are Protozoa/Protozoan?
are unicellular eukaryotic organisms that lack cell walls
Name properties of protozoa
are free living and are found in soil and in a variety of freshwater and marine habitats
are motile and chemoheterotrophic
food is digested within a food vacuole
osmotic pressure is regulated by the contractile vacuole (eliminates excess water)
mostly aerobic, except intestinal can grow anaerobically
A large number of protozoa are part of?
the normal microbiota of humans and animals
What do protozoa feed on? (Nutrition)
feed upon bacteria and small particulate or macromolecular materials
some ingest tissue cells of the host
What is a pellicle?
a protective covering on protozoa which prevents transport of nutrients across the plasma membrane
amoebas engulf food by?
surrounding it with pseudopodia and phagocytizing it
cilates engulf food by?
waving cilia toward a mouthlike opening
What is a cytostome?
mouthlike opening on ciliates
What is a food vacuole?
membrane-enclosed place where food is digested in ALL protozoa
What are the three was Protozoa excrete waste products?
may occur directly through the plasma membrane
by means of contractile vacuoles through the cell wall
a specialized anal pore
How do protozoa reproduce?
many protozoa are able to reproduce both sexually and asexually
in some only asexual occurs
What is binary fission?
the most common asexual reproduction among protozoa
two daughter cells result from a "parent" cell, division occurring mostly along the longitudinal axis or ocassionally, across the transverse plane
the nucleus divides first, followed by cytoplasmic division
What is Budding?
is a process in which two or many daughter forms are produced by the "parent cell"
there is usually and unequal fragmentation of the nucleus and the cytoplasm, but the forms are separated off and then grow to full size.
What is schizogony (multiple fission)?
the nucleus undergoes multiple divisions before the cell divides.
after many nuclei are formed, each nucleus becomes associated with a portion of cytoplasm and little or nothing of the parent cell remains except the greatly expanded limiting membrane.
the single cell then separates into daughter cells
What is a schizont?
the dividing form in schizogony
What are merozoites?
the daughter forms in schizogony
What is conjugation?
the form of sexual reproduction in ciliates
Describe what happens during conjugation
two organisms pair and the micronucleus from each organism migrates to the other organism.
the micronucleus fuses with the macronucleus within the organism,
the parent organisms separate, each now is a fertilized cell.
both organisms will later divide, producing two daughter cells with recombinant DNA.
the nucleus divides to give rise to a new macronucleus and micronucleus
What are the two nuclei in ciliates?
What is syngamy?
protozoa produce gametes
during reproduction, a microgamete fuses with a macrogamete to form a diploid zygote
What are microgamete?
What are macrogamete?
What is sporogony?
an asexual process of multiple fission
follows syngamy, and a number of sporozoites are formed within the walls of a cyst from the zygote
What is encystment?
the cell may assume a fairly round or oval shape and secrete a protective capsule around itself under certain adverse environmental conditions.
during this the cell may survive a lack of food or moisture, adverse temperature changes, or contact with toxic chemical agents.
The cyst from encystment is valuable because?
allowing parasitic forms to survive outside the host until they can enter a new host.
when favorable conditions arise, water is absorbed, and organism emerges and can resume growth
What are the Major groups of protozoa?
Describe flagellates (mastigophora)
members of this group are motile by the action of flagella
many are free-living organisms
many are parasitic in, or pathogenic for animals and humans
spindle shaped with flagella projecting from the front end
most have two or more flagella
flagella also serve as food-capturing organelles
What are mucosoflagellate?
are found in the lumen of the intestine and other mucosal sites