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

Testate amoeb

asCentropyxis sp. Arcella sp.

Difflugia 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!