Defining Protista

Lesson Plan - Get It!

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This lesson will give you a brief introduction to the organisms of the Protista Kingdom, one of the six kingdoms of classification.

This kingdom includes organisms like slime molds, water molds, algae, and protozoa. Protists are eukaryotic organisms that are NOT plants, animals, bacteria, or fungi.

Protists can be multicellular or unicellular. Some are heterotrophic, meaning they must find a food source, while other are autotrophic like plants, and can make their own food from sunlight.

Protists also vary greatly in size and can be microscopic or very large.

There’s no organism that can be classified as a typical protist. They are grouped together in this kingdom because they are all eukaryotes.

Organisms that carry out most of their metabolic processes inside their membrane organelles are called eukaryotes.

Metabolic process is the organic process (in a cell or organism) that is necessary for life.

The organelles are the tiny structures within a cell that carry out specific functions.

For more information about the functions of organelles, check out Prokaryotes, Eukaryotes, & Viruses Tutorial: Eukaryotes.

Protists are made up of eukaryotic cells, meaning that the nucleus in the cell has a membrane around it, unlike prokaryote bacteria cells that have a nucleoid without a membrane.

Organisms in the plant, animal, fungi, and Protista kingdoms all are made of eukaryote cells. Bacteria from the eubacteria and archaebacteria kingdoms are prokaryotic.

• Are there any other similarities and differences between the two cells pictured below?

Some protists resemble animals in how they get their food source, and they are called protozoa. However, unlike animals, they are unicellular.

The protists that resemble plants are called algae; however, they are somewhat different from plants. They do not have organs like leaves, roots, and stems.

Other algae are like fungi, because they decompose dead organisms. These types of protists are also able to move about at some point in their life.

Protists can affect your health and life. Some protists cause diseases like malaria, while the unicellular algae are responsible for producing a lot of the oxygen in the earth’s atmosphere.

Explain in your own words what eukaryotes are and why the metabolic processes and organelles are important.

In the Got It? section, you will learn more about malaria, a disease caused by a certain species of protist.