The Protozoans

11.1 Emergence of Eukaryotes

What is a eukaryote?

An organism composed of one or more cells containing visible evidence of nuclei and organelles.

How did eukaryotes evolve?

cellular symbiosis among prokaryotic cells

What is a symbiosis?

When two dissimilar organisms live together and form an intimate and life- sustaining relationship that is mutually beneficial.

What is a prokaryote?

A cellular organism (such as bacterium or blue- green alga) that does not have a distinct, membrane-bound nucleus.

How did Cellular Symbiosis happen?

Since: 1) Apparently, the first cells to appear in the fossil record (3.5 billion years ago) were bacteria-like and prokaryotic

How did Cellular Symbiosis happen? Since: 1) Apparently, the first cells to appear in the fossil record (3.5 billion years ago) were bacteria-like and prokaryotic AND: 2) Eukaryotic cells have organelles and a nucleus,

Cellular Symbiosis Scientists postulate or hypothesize that: The origin of complex eukaryotic cells was most likely a type of symbiosis among prokaryotic cells.

Cellular Symbiosis Scientists postulate or hypothesize that: The origin of complex eukaryotic cells was most likely a type of symbiosis among prokaryotic cells. This may have involved aerobic bacteria which were engulfed by anaerobic bacteria that were unable to tolerate the increasing oxygen (anaerobic) in the atmosphere caused by photosynthetic bacteria. These engulfed aerobic bacteria had the necessary enzymes for deriving energy in the presence of oxygen and may have become the mitochondria found in most modern eukaryotic cells.

Similarly, Scientists hypothesize that: Engulfed photosynthetic bacteria evolved into chloroplasts; which are the descendants of the green algae lineage, later giving rise to multicellular plants.

Protozoa are a diverse assemblage with mixed characteristics: a. They lack a cell wall, unlike plants b. They have at least one motile stage in the life cycle. c. Most ingest their food.

Contributions to Biological Complexity 1. Protozoa have intracellular specialization or organization of organelles in cells.

Contributions to Biological Complexity 1. Protozoa have intracellular specialization or organization of organelles in cells. 2. Cells may have distinct functions; some colonial protozoa have separate somatic and reproductive zooids.

Contributions to Biological Complexity 1. Protozoa have intracellular specialization or organization of organelles in cells. 2. Cells may have distinct functions; some colonial protozoa have separate somatic and reproductive zooids. 3. Asexual reproduction occurs by mitotic division.

Contributions to Biological Complexity 1. Protozoa have intracellular specialization or organization of organelles in cells. 2. Cells may have distinct functions; some colonial protozoa have separate somatic and reproductive zooids. 3. Asexual reproduction occurs by mitotic division. 4. Some have true sexual reproduction with zygote formation.

Contributions to Biological Complexity 5. Responses to stimuli represent the simplest reflexes and inborn behaviors known.

Contributions to Biological Complexity 5. Responses to stimuli represent the simplest reflexes and inborn behaviors known. 6. Shelled protozoa have the simplest exoskeletons.

Contributions to Biological Complexity 5. Responses to stimuli represent the simplest reflexes and inborn behaviors known. 6. Shelled protozoa have the simplest exoskeletons. 7. Basic enzymes systems support all types of nutrition: autotrophic, saprozoic and holozoic.

Contributions to Biological Complexity 5. Responses to stimuli represent the simplest reflexes and inborn behaviors known. 6. Shelled protozoa have the simplest exoskeletons. 7. Basic enzymes systems support all types of nutrition: autotrophic, saprozoic and holozoic. 8. Many have developed means of locomotion.

General Features 1. Over 64,000 species are named; half are fossils.

General Features 1. Over 64,000 species are named; half are fossils. 2. Although they are unicellular organisms, protozoan cell organelles are highly specialized.

General Features 1. Over 64,000 species are named; half are fossils. 2. Although they are unicellular organisms, protozoan cell organelles are highly specialized. 3. They are ecologically diverse, widely dispersed, but many are limited to narrow environmental ranges.

General Features 1. Over 64,000 species are named; half are fossils. 2. Although they are unicellular organisms, protozoan cell organelles are highly specialized. 3. They are ecologically diverse, widely dispersed, but many are limited to narrow environmental ranges. 4. They can be fantastically numerous, forming gigantic ocean soil deposits.

General Features 5. About 10,000 are symbiotic in or on animals or plants; some are human disease agents.

General Features 5. About 10,000 are symbiotic in or on animals or plants; some are human disease agents. 6. Some are colonial with multicellular stages but have noncolonial forms.

General Features 5. About 10,000 are symbiotic in or on animals or plants; some are human disease agents. 6. Some are colonial with multicellular stages but have noncolonial forms. 7. Protozoa have only one non-reproductive cell type and lack embryonic development; embryonic development is one of the criteria for metazoa.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages. 2. Most are microscopic.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages. 2. Most are microscopic. 3. All symmetries are present within members of the group.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages. 2. Most are microscopic. 3. All symmetries are present within members of the group. 4. No germ layers are present.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages. 2. Most are microscopic. 3. All symmetries are present within members of the group. 4. No germ layers are present. 5. No organs or tissues are formed, but specialized organelles serve many of these functions.

Characteristics of Protozoan Phyla 1. They are unicellular with some colonial and multicellular stages. 2. Most are microscopic. 3. All symmetries are present within members of the group. 4. No germ layers are present. 5. No organs or tissues are formed, but specialized organelles serve many of these functions. 6. They include free-living, mutualistic, commensal and parasitic forms.

Characteristics of Protozoan Phyla 7. They move by pseudopodia, flagella, cilia and they can direct cell movements.

the physiology of movement

Pseudopodia in - Phylum: Sarcomastigophora, Subphylum: Sarcodina AMOEBA

Cilia in - Phylum: Ciliophora, Class: Oligohymenophora Genus: PARAMECIUM

Flagella in - Phylum: Sarcomastigophora, Subphylum: Mastigophora, Class: Phytomastigophorea EUGLENA

Characteristics of Protozoan Phyla 7. They move by pseudopodia, flagella, cilia and they can direct cell movements. 8. Most are naked, but some have a simple endoskeleton or exoskeleton.

Characteristics of Protozoan Phyla 7. They move by pseudopodia, flagella, cilia and they can direct cell movements. 8. Most are naked, but some have a simple endoskeleton or exoskeleton. 9. All types of nutrition are present: autotrophic, heterotrophic and saprozoic.

Characteristics of Protozoan Phyla 7. They move by pseudopodia, flagella, cilia and they can direct cell movements. 8. Most are naked, but some have a simple endoskeleton or exoskeleton. 9. All types of nutrition are present: autotrophic, heterotrophic and saprozoic. 10. They can be aquatic or terrestrial, and free- living, symbiotic or parasitic.

Characteristics of Protozoan Phyla 7. They move by pseudopodia, flagella, cilia and they can direct cell movements. 8. Most are naked, but some have a simple endoskeleton or exoskeleton. 9. All types of nutrition are present: autotrophic, heterotrophic and saprozoic. 10. They can be aquatic or terrestrial, and free- living, symbiotic or parasitic. 11. Reproduction is asexual by fission, budding or cysts; or sexual by conjugation or syngamy of gametes.

Phytomastigophorea

Phytomastigophorea

Zoomastigophorea

Sarcodina

Slime molds

Actinopoda

Apicomplexa Plasmodium and malaria

ciliates