Diversity and Ecology MW Lecture 16 What are Protists? Protists are eukaryotes (organisms whose cells are organized into complex structures enclosed within membranes with a true nucleus) All protists live in water, moist soil, or the moist interiors of other organisms. Many protists, such as the algae, are photosynthetic and are vital primary producers in ecosystems, particularly in the ocean. Other protists are responsible for a range of serious human diseases, such as malaria and sleeping sickness. Photography Copyright D.Bausch. Public Domain Access Granted.

The Origin of Eukaryotic Cells Eukaryotic cells are believed to have developed when a primitive prokaryotic cell engulfed aerobic bacteria. These aerobic bacteria were not broken down within the prokaryotic cell, but rather, developed into mitochondria which used oxygen to convert the energy stored in food into energy that is able to be used by the prokaryotic cell. These cells evolved into animals, fungi, or protists. The Brain from Top to Bottom. Retrieved on July from a_05_cl_her_1b The Brain from Top to Bottom

The Origin of Eukaryotic Cells Plants continued this process a step further and are believed to have then engulfed photosynthetic bacteria which then evolved into chloroplasts. Chloroplasts are responsible for the photosynthetic process which plants use to create sugars from carbon dioxide and sunlight. The Brain from Top to Bottom. Retrieved on July from a_05_cl_her_1b The Brain from Top to Bottom

Diversity and Ecology MW Lecture 16 What are Protists? Animals, such as humans, are made up trillions of single cells, therefore we are multi-cellular. However, in multi-cellular organisms each cell is not considered an individual organism. Protists, however, are organisms that are primarily made of only one cell. Protists can multi-cellular but they do not have specialized tissues. This distinguishes the protists from other eukaryotes such as fungi, animals and plants. Photography Copyright D.Bausch. Public Domain Access Granted.

Surface waters of oceans and lakes have an abundance of protists called diatoms In some near-shore areas, gigantic protists, such as kelp, form underwater forests Protists are particularly abundant in tidal habitats Protists, such as algae, are the leading primary producers in oceans and are the basis for marine and freshwater food chains. Kip Evans. Retrieved on July from Wikimedia Commons. Public Domain Access. Merbabu. Retrieved on July from Wikimedia Commons. Prof. Gordon T. Taylor, Stony Brook University. Retrieved on J uly from Wikemedia Commons. Public Domain Access. Britannica Online. Retrieved on July from

Monday, October 27, 2003 Examples of different protists. Photography Copyright D.Bausch. Public Domain Access Granted.

Types of Protists Animal like protists (Protozoans) Eg. amoeba, ciliates, flagellates They are considered animal like because they consumer other organisms to obtain nutrients. Some of these protists are parasites. Fungus like protists Eg. slime moulds and water moulds They are considered fungus like because they consume nutrients from living or dead organisms Some water moulds are parasites. Plant like protists Eg. euglenoids, diatoms, dinoflagellates They are considered plant like because they make their own food by photosynthesis. Some can consume other organisms and some are symbionts within other organisms. Gregorius28. Retrieved on July from mmons.org. Public Domain Access. Stentor Hannes Grobe. Retrieved on July from mmons.org. Public Domain Access. Diatom Slime Mould US Government National Park Service. Retrieved on July from Wikpedia Commons Online. Public Domain Access.

Protists have different ways of moving Some protists move by means of CILIA. Cilia are hair- like projections which beat together like oars to push the protist through its environment. National Human Genome Research Institute. Retrieved on July from Public Domain Access.

Protists have differents ways of moving Some protists move by means of A FLAGELLUM. Flagella are tail like projections which rotate like a propeller to push the protist through its environment National Oceanic and Atmospheric Administration. Retrieved on July from Wikmedia Commons. Public Domain Access. Mike Jones. Retrieved on July from Public Domain Access.

Protists have different ways of moving Some protists move by means of PSEUDOPODIA. Pseudopods are temporary projections of the protist which push its body in a particular direction. The fluid within the cell is pushed against the cell wall which causes it to extend. Pseudopod Amoeba Tsukii Yuuji. Retrieved on July from Public Domain Access.

Protists feed in a different ways: Some engulf (swallow) bacteria and other food materials in pseudopods by surrounding it with arm like structures, like this amoeba engulfing a bacteria. Some parasites have developed the ability to penetrate a host and absorb its nutrients, like this trypanosoma protist swimming alongside the red blood cells of its host. Trypanosoma causes African sleeping sickness. Some protists are filter feeders that have hundreds of small hairs called cilia near their mouths. The cilia beat very rapidly and pull in smaller organisms and nutrients, like this rotifer. PHIL_613_lores. Centers for Disease Control and Prevention's Public Health Image Library. Retrieved on July from Wikipedia Commons Online. Public Domain Access. Jockersam. Retireved on July from org/File:Stentor123.jpg