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Protists
Protists are eukaryotic organisms. This means that they have membrane-bound organelles anda nucleus with chromosomes. Scientists think that the first eukaryotes may have begun as large prokaryotic cells. The DNA of some eukaryotic organelles is very similar to that of bacteria (namely the mitochondrial DNA). Because the DNA is similar, scientists think that the organelles may at one time have been independently living bacteria. These bacteria somehow entered the larger prokaryotes and eventually became the organelles of the larger cell. This theory is referred to as endosymbiosis (endo meaning inside). This is how scientists believe mitochondria and cholorplasts came to exist as organelles in eukaryotic organisms.
There are more than 50,000 species of protists. Many live as single celled organisms. Others are actually multicellular. Some protists are heterotropic while others are autotrophic through the process of photosynthesis.
Protists have great medical importance because several cause diseases in humans. However, they are also of great ecological importance. Being aquatic, the photosynthetic protists give off oxygen and function as producers in both fresh and saltwater ecosystems. They are a part of plankton, which are organisms that are suspended in water and serve as food for heterotrophic protists and animals.
Protists can be divided into categories based on their nutrition. There are plant like (photosynthetic) protists, animal like (heterotrophic) and fungi like (decomposers) protists. The term protozoan is often used to describe the animal like protists.
Many protists reproduce asexually by mitosis (binary fission). The parent cell simply divides into two identical daughter cells. Soem protists, however, can reproduce sexually under some conditions. During sexual reproduction, two organisms become attached to each other in a process called conjugation. They share their DNA allowing for new genetic combinations.
If you cannot view the video below, you may find it within the assignments folder in Bb.
There are more than 50,000 species of protists. Many live as single celled organisms. Others are actually multicellular. Some protists are heterotropic while others are autotrophic through the process of photosynthesis.
Protists have great medical importance because several cause diseases in humans. However, they are also of great ecological importance. Being aquatic, the photosynthetic protists give off oxygen and function as producers in both fresh and saltwater ecosystems. They are a part of plankton, which are organisms that are suspended in water and serve as food for heterotrophic protists and animals.
Protists can be divided into categories based on their nutrition. There are plant like (photosynthetic) protists, animal like (heterotrophic) and fungi like (decomposers) protists. The term protozoan is often used to describe the animal like protists.
Many protists reproduce asexually by mitosis (binary fission). The parent cell simply divides into two identical daughter cells. Soem protists, however, can reproduce sexually under some conditions. During sexual reproduction, two organisms become attached to each other in a process called conjugation. They share their DNA allowing for new genetic combinations.
If you cannot view the video below, you may find it within the assignments folder in Bb.