Transcript Protists chapter 28

By: Pablo J Fonseca
*(with help and information from Google search engine and
Campbell Reece AP biology textbook)
What is a Protist? A Protist is
virtually any eukaryote that
is neither a plant, animal, or
fungi. Throughout this
PowerPoint I will introduce
you with some of the most
significant groups of protists.
You will learn about their
structural and biochemical
adaptations as well as their
enormous impact on
ecosystems, human health,
industry, and the world.
http://www.youtube.com/watch?v=-zsdYOgTbOk
• Protists exhibit more structural and functional diversity than any other
group of organisms.
• Most protists are unicellular ( meaning composed of only 1 cell), although
there are some colonial and multicellular species( meaning having multiple
cells).
• Even though most protists are unicellular and are only composed of one cell
this doesn’t mean that they are very simple in fact in some cases it can be
considered quite the opposite. This should be expected of a cell though
that has to carry out all the functions that a multicellular organism does.
• As well must Protist at the cellular level become exceedingly complex.
• Protist are the most nutritionally diverse of all eukaryotes.
• There are also many different ways Protist acquire they're nutriention.
• some Protist are photoautotrophs containing chloroplasts. Some are
Heterotrophs absorbing organic molecules or ingesting large food particles.
• Yet the most remarkable of the Protist to obtain they're nutrition are the
Mixotrophs(Mixotrophs combine photosynthesis and heterotrophic nutrition.)
• In such an ecological context, we can divide protists into three categories:
photosynthetic protists mean plant like, or algae; ingestive( animal like) protists,
or protozoans; and absorptive (fungus like protists)
• The places Protist inhabit are diverse as well as it ranges from rocks to water.
• Overall though it has been proven scientifically that Protist prefer aquatic
environments. They are found almost anywhere there is water, including moist
terrestrial habitats such as damp soil and leaf litter. In ocean, ponds, and lakes,
many protists are bottom dwellers that attach themselves to rocks and other
substrates or creep through the sand and silt.
• Reproduction and life cycles highly varies throughout different protists.
• Some Protist are asexual and others can reproduce sexually or at least employ
the sexual processes of meiosis and syngamy. All three basic types of sexual
life cycles are represented among protists, along with some variations that do
not quite fit any of these types.
Now that we have examined some of the broad patterns in eukaryotic evolution, we
will look more closely at several of the main clades of Protist.
We begin with diplomonadida and Parabasalids. Protist in these 2 clades lack
plastids, and they’re mitochondria do not posses DNA, electron transport
chains, or enzymes that are normally needed for the citric acid cycle.
- Diplomads have two equal sized nuclei and multiple flagella.
- Parabasalids include the Protist called trichomonad. The most well-known
species is trichomonad vaginalis, a common inhabitant of the vagina of
human females
• Eugenozoans is a diverse clade that includes predatory heterotrophs,
photosynthetic autotrophs, and pathogenic parasites. The main features that
differentiate the protists in the clade are their flagella.
• Kinetoplastids have a single, large mitochondrion that contains an organized mass
of DNA called a kinetoplast.
• Euglenids have a pocket at one end of the cell from which one or two flagella
emerge.
Another clade of protists whose identity is emerging from molecular systematics, Alvolata , is
characterized by membrane bound sacs just under the plasma membrane. The function of the
alveoli is unknown; researches hypothesize that they may help stabilize the cell surface or
regulate the cell’s water and ion content.
- Dinoflagellates are abundant components of both marine and freshwater phytoplankton.
There are also heterotrophic Dinoflagellates. Of the several thousand known
Dinoflagellates most are unicellular, but some are colonial. Each has a characteristic
shape that in many species is reinforced by internal plates of cellulose. Two flagella
located in perpendicular grooves in this “armor” make Dinoflagellates spin as they move
through water.
- Apicomplexans are parasites of animals, and some cause serious human diseases. The
parasites spread though their host as tiny infectious cells called Sporozoties.
- Ciliates are a large, varied group of protists named for their use of cilia to move and
feed.
- Conjugation In prokaryotes, the direct transfer of DNA between two cells that are
temporally joined. In ciliates, a sexual process in which two cells exchange haploid micro
nuclei.
Diatoms are unicellular algae that have a unique glass-like wall made of
hydrated silica embedded in an organic matrix.
Algae
-golden algae, or cryophytes, are named for their color, which results from their
yellow and brown carotenoids.
- Brown algae the largest and most complex type of algae are brown algae,
or phaeophyte. All are multicellular, and most are marine. Brown algae are
especially common among temperate coasts, where the water is cool. Brown
algae is very often your common seaweed.
- Now while seaweed may seem simple to the
Eye that is very deceiving because some
Seaweeds are actually quite complex.
Seaweed is composed of holdfast, blades,
And stipes. Please open your book to pg.560
For more info.
The clade stramenopiles includes several groups of heterotrophs as well as certain
groups of algae. The name of the clade refers to a flagellum with numerous fine, hair
like projections, a characteristic of these protists. In most stramenopiles, this “hairy”
flagellum is paired with a smooth(non-hairy) flagellum. In some stramenopiles groups,
the only flagellated cells are motile reproductive cells.
- Oomycetes include water molds, white rusts, and downy mildews. Early morphological
studies show that these organisms show that they organisms are fungi.
Alternation of generations- A life cycle in which there is both a multicellular
diploid form, the sporophyte, and a multicellular haploid form, the gametophyte;
characteristic of plants and some algae.
• Heteromorphic meaning that the sporophytes and gametophytes are
structurally different.
• Isomorphic generations in which the sporophytes and gametophytes look
similar to each other, although they differ in chromosome number.
A relatively young new clade, Cercozoans, contains a diversity of species that are among
the organisms referred to as amoebas. Amoebas were formally defined as protists that
move and feed by means of pseudopodia, extensions that may bulge from virtually any
where on the cell surface.
• Foraminiferans, or forams, are named for their porous shells, called tests. Foram tests
are generally multichambered and consist of organic material hardened with calcium
carbonate.
• Radiolarians are mostly marine protists whose test are fused into one delicate piece.
• Red algae have colors ranging from green to black, owning
varying amount of the accessory pigment phycoerythrin. Most
red algae are multicellular.