Protist Structure and Function

Learning Objectives Describe the various methods of protist locomotion. Describe how protists reproduce.

Protists Motion: Amoeboid Movement

• Move by changing shape• Use cytoplasmic projections called pseudopods

Pseudopod

Protist Motion: Cilia

Motion by cilia is like oars propelling a large rowboat forward.

Cilia

Protist Motion: Flagella

Motion by some flagella is like the back-and-forth movement of a single long oar at the back of a boat, propelling it forward.

Flagellum

Protist Motion: Passive

• Nonmotile• Form reproductive structures called spores

Protists Reproduction: Cell Division

Amoebas and many other protists produce new individuals through mitosis.

Protist Reproduction: Conjugation

Macronucleus

Micronucleus Micronucleus undergoes meiosis.

Three micronuclei disintegrate.

Remaining micronucleusundergoes mitosis.

Protist Reproduction: Conjugation, cont.

Cells exchange one micronucleus.

Micronuclei fuse; macronucleus disintegrates.

New macronucleus forms from

micronucleus.

Diploid

Alternation of Generations: Overview

Fertilization

Meiosis

Asexual reproduction

Sexual reproduction

Alternation of Generations: Asexual Stage

Sporangium

Flagellated spores

Spores undergo mitosis.

2N

Alternation of Generations: Sexual Stage

Male reproductive structure

Female reproductive structure

Zygotes

Fertilization

Meiosis

Egg cell

Male nuclei

2N

Overview: Locomotion and ReproductionLocomotion

1.

2.

3.

4.

Reproduction

Many protists undergo

to produce genetically identical offspring.

In alternation of generations, an organism goes through a

and an stage.

mitosis

asexual

sexual

Amoeboid movement

Passive movement

Use of cilia

Use of flagella