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.30.2010 from a_05_cl_her_1b The Brain from Top to Bottom http://thebrain.mcgill.ca/flash/a/a_05/a_05_cl/a_05_cl_her/a_05_cl_her.html

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.30.2010 from a_05_cl_her_1b The Brain from Top to Bottom http://thebrain.mcgill.ca/flash/a/a_05/a_05_cl/a_05_cl_her/a_05_cl_her.html

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 areparticularly

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.30.2010 from Wikimedia Commons. Public Domain Access.

Merbabu. Retrieved on July.30.2010 from Wikimedia Commons.

Prof. Gordon T. Taylor, Stony Brook University. Retrieved on July.30.2010 from Wikemedia Commons. Public Domain Access.

Britannica Online. Retrieved on July.30.2010 from http://www.britannica.com/EBchecked/topic/212636/food-chain.

Monday, October 27, 2003

Examples of different protists.

Photography Copyright D.Bausch. Public Domain Access Granted.

Types of ProtistsAnimal 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 protistsEg. 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 protistsEg. 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.28.2010 from http://www.wikicommons.org. Public Domain Access.

Stentor

Hannes Grobe. Retrieved on July.28.2010 from http://www.wikicommons.org. Public Domain Access.

Diatom

SlimeMould

US Government National Park Service. Retrieved on July.30.2010 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.30.2010 from http://www.genome.gov/pressDisplay.cfm?photoID=85. 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.30.2010 from Wikmedia Commons. Public Domain Access.

Mike Jones. Retrieved on July.30.2010 from http://commons.wikimedia.org/wiki/Image:Flagella.png. 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

AmoebaTsukii Yuuji. Retrieved on July.28.2010 from http://www.wikicommons.org. PublicDomain 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.30.2010 from Wikipedia Commons Online. Public Domain Access.

Jockersam. Retireved on July.30.2010 from http://creationwiki.org/File:Stentor123.jpg