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Protozoa II
Chapter 8
Outline
• Protection
• Feeding strategies
• Reproduction
– Sexual
– Asexual
• Life cycle
Amoeba Tests
• Sand and Chitin
• Calcium Carbonate
– Foraminifora:
marine
• Silica
– Radolarians:
marine forms,
oldest, known
protists
Difflugia sp.
Centropyxis sp.
Testate
amoeb
as
Arcella sp.
Amoeba Tests
• Sand and Chitin
• Calcium Carbonate
– Foraminifora: marine
• Silica
– Radolarians: marine
forms, oldest, known
protists
Amoeba Tests
• Sand and Chitin
• Calcium Carbonate
– Foraminifora: marine
• Silica
– Radolarians: marine
forms, oldest, known
protists
Feeding Strategies
1. Autotrophs- synthesize their own food
2. Heterotrophs- consume food made by
others
--Osmotrophs-ingest food in soluble form.
--Phagotrophs-ingest visible particles of food.
Phagotrophs
I. Sucking
II. Feeding currents
III. Pseudopods
General Feeding Process
General Feeding Process
1. Food (prey) particle is brought near the body
General Feeding Process
1. Food (prey) particle is brought near the body
2. Particle is brought into the cell by infolding
or invagination
--Food vacuole or phagosome
General Feeding Process
1. Food (prey) particle is brought near the body
2. Particle is brought into the cell by infolding
or invagination
--Food vacuole or phagosome
3. Lysosomes fuse with vacuole
General Feeding Process
1. Food (prey) particle is brought near the body
2. Particle is brought into the cell by infolding
or invagination
--Food vacuole or phagosome
3. Lysosomes fuse with vacuole
4. As food is digested, its products are taken
into the cell across the vacuole membrane
General Feeding Process
1. Food (prey) particle is brought near the body
2. Particle is brought into the cell by infolding
or invagination
--Food vacuole or phagosome
3. Lysosomes fuse with vacuole
4. As food is digested, its products are taken
into the cell across the vacuole membrane
5. Undigested food is expelled
Food
Lysosome
Food vacuole
Getting rid of waist
• Egestion vacuoles, release waist by
exocytosis, and some protozoans have a
specialized region of the plasma
membrane or pellicle to do this The
CYTOPYGE!
I. Sucking
• By tentacles
• Suctorian ciliate
• Use long narrow
tentacles to attach
to prey items
• Tentacles help it
move food into the
cell
I. Sucking
• Using the oral groove
• e.g. Didinium (ciliate)
• Attaches to prey item
and ingests food
through a temporary
cytostome (cell
mouth)
Feeding Using the Cytostome
II. Feeding Currents
• This is a semi-passive feeding mechanism
in which food is brought to the oral
opening by creating water currents
• Used by ciliates and flagellates
• Organism usually sessile
Codosiga
Flagellar feeding currents
• Particles are
brought into the
collar
• Pseudopods move
the particles into
the cell
III. Pseudopods
• Used by amoebae
• Pseudopods
surround food
particles
• Encloses it inside
body
Protozoan Reproduction
• Asexual
1. Binary fission
2. Budding
3. Multiple fission
Sexual
4. Conjugation
I. Binary fission
• Division of
one parent
individual
into two equal
daughter
individuals
Life Cycle of Trypanosoma
brucei
Trypanosoma brucei: African
Sleeping Sickness
The Vector Glossina
African Trypanosomiasis Course
of Infection
• Invasion of Central Nervous System-African
Sleeping Sickness.
II. Budding
• Division of one
parent individual
into two or more
unequal daughter
individuals.
• The smaller
daughter
individual must
mature.
III. Multiple fission
• Division of one
parent individual
into numerous
individuals,
simultaneously.
Life cycle of
Plasmodium
(Malaria)
Ciliate life cycle
• Life cycles include
– Asexual binary fission
– Conjugations (sexual): temporary union of
two individuals for the function of
exchanging genetic material
The Big Picture
• Protists can be divided into two main groups
depending on feeding strategy.
• Phagocytosis is a common type of feeding
strategy
• How phagocytic protists feed differs widely
• Reproduction in protists is mainly by binary
fission, ciliates and apicomplexans have sexual
reproduction!