What is a Protist? Watch this video http://www.youtube.com/watch?v=8deF3Rw4ti4

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What is a Protist?Watch this video
http//www.youtube.com/watch?v8deF3Rw4ti4feature
related

• How are Protists related to other eukaryotes?

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Does everyone agree how to classify protists?

• No, at present, biologists do not agree how to
  classify protists
• The amount of diversity among the protists, is
  much greater than within or between the other
  three eukaryotic kingdoms

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The Protist Dilemma

• Protists are grouped together solely because they
  are not fungi, plants or animals
• Furthermore, many protists are more closely
  related to members of other eukaryotic kingdoms
  than they are to other protists.

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Current Protist classification

• It has been proposed that the protista kingdom be
  divided into six groups or clades
• Today, while we still use the term Protist, this
  is not a single kingdom, but a collection of
  organisms in six clades

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What is a Protist?

• A protist is a eukaryote (has a nucleus)
• A protist is any eukaryote that is not a plant,
  animal or fungus

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Turn to page 604

• List the names of the 6 major groups of protists
• Which group is most closely related to plants?
  Animals? Fungi

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Are all protists unicellular?

• No, although most are unicellular, some protists
  are colonial, and some like the giant kelp are
  multicellular.

Unicellular Colonial Multicellular
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Evolution of ProtistaEndosymbiont Hypothesis
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How do Protists move?

• Some move and feed with pseudopods (amoeboid
  movement)
• Example
• Amoebas

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How do Protists Move?

• Some move with flagella
• Long whip-like projections
• One to two per cell
• Examples
• Trypanosoma
• Euglena

Trypanosoma
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Euglena

• Two flagella
• No cell wall
• Chloroplasts

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How do Protists move?

• Some move with cilia
• Cilia can be used for feeding and movement
• Cilia are short and used like oars on a boat
• Example
• Paramecium

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Some do not move

• Those that do not move produce spores and live as
  parasites
• Plasmodium causes malaria
• Cryptosporidium spreads through contaminated
  drinking water and caused intestinal disease

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Excavates feeding groove, flagella

• Diplomonads
• Giardia is an intestinal parasite that causes
  cramping and diarrhea
• Discicristates
• Euglena is free living and can use its
  chloroplast for photosynthesis or can live as a
  heterotroph
• Trypansoma causes African sleeping sickness
  carried by tsetse flies

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Giardia infection
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Euglena
Chloroplast
Carbohydrate storage bodies
Gullet
Pellicle
Contractile vacuole
Nucleus
Eyespot
Flagella
Go to Section
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Chromalveolates very diverse group most are
photosynthetic

• Phaeophytes multicellular brown algae
• Chrysophytes unicellular golden algae
• Diatoms unicellular algae with intricate
  silicon dioxide (silica) shells
• Ciliates paramecium are not photosynthetic
• Dinoflagellates half are photosynthetic, half
  are heterotrophs some are luminescent
• Apicomplexans parasitic Plasmodium

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Brown algae

• Phaeophytes
• Photosynthetic
• Chlorophylls a and c
• Brown accessory pigment fucoxanthin
• Multicellular
• Giant kelp, Fucus

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Photosynthetic protists

• Chrysophytes
• Golden plants
• Gold-colored chloroplasts
• Cell walls contain pectin instead of cellulose
• Store food as oil rather than starch
• Can form thread like colonies

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Photosynthetic protists

• Diatoms
• Glass like cell walls
• Cell walls contain silicon (Si)
• Cell walls like petri dish

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Ciliates - Paramecium
Go to Section
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Photosynthetic protists

• Dinoflagellates
• Luminescent
• Fire plants
• Half photosynthetic
• Half heterotrophs
• Two flagella

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Apicomplexan

• Plasmodium
• Mosquito borne parasites like the species that
  causes malaria

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Cercozoa, Foramineferan, Radiolarian

• Have pseudopods
• Many produce protective shells

Foraminiferans
Heliozoan
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Rhodophytes

• Red Algae
• Chlorophyll a
• Red accessory pigment phycobilin
• Absorbs blue light
• Grows very deep
• Multicellular
• Nori

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Photosynthetic protists

• Photosynthetic protists are often called algae
• It is hard for algae to get light since much of
  the lights energy is absorbed by water
• Seawater absorbs red and violet light
• Photosynthetic protists have accessory pigments
  to absorb light at different wavelengths than
  chlorophyll.

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Ecology of photosynthetic protists

• Base of the food chain
• Half of the photosynthesis on earth is carried
  out by phytoplankton

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Ecology of photosynthetic protists

• Algal blooms
• Caused by too much pollution or nutrients
• Deplete water of oxygen
• Kill fish and invertebrates
• Dinoflagellates cause red tides
• Red tides produce toxins which can be taken in by
  shellfish. Eating these shellfish can cause
  illness, paralysis and death

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Green algae

• Phylum Chlorophyta
• Same chlorophyll and cell wall composition as
  green plants
• Chlorophyll a and b
• Store food as starch
• Found in fresh and salt water and on land
• Unicellular, colonial and multicellular
• Now classified with plants

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Unicellular green algae

• Chlamydomonas
• Lives in ponds, ditches and wet soil
• Egg shaped
• Two flagella
• Large, cup-shaped chloroplast

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Colonial green algae

• Spirogyra
• Filamentous
• Forms threadlike colonies
• Spiral chloroplasts
• Volvox
• Hollow spheres
• 500 50,000 identical cells
• Some cell specialization

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Human uses of algae

• Oxygen
• Food (nori thickening agent (carrageenan) in ice
  cream, egg nog, chocolate, salad dressing)
• Industry (plastics, waxes, paints, lubricants)
• Science labs (agar)

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• Alternation of generation alternating between
  diploid and haploid organisms
• Diploid having two copies of each chromosome
• Haploid having one copy of each chromosome
• Gametophyte haploid gamete producing organism
• Sporophyte diploid spore producing organism

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Heterotrophic protists

• Amoebozoa Amoebas use pseudopods for movement
  and feeding
• Ciliates Paramecia use cilia to move food to
  gullet food vacuoles and lysosomes digest the
  food waste is released through the anal pore
• Slime Molds and Water Molds absorb food through
  their cell walls from dead or decaying matter
  decomposers

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Section 20-2
An Amoeba
Go to Section
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Slime molds
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Slime molds
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Water molds

• Cells are multinucleate
• Cell walls of cellulose
• White fuzz on dead fish in water
• Plant parasites on land

Cause potato blight responsible for potato famine
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Reproduction in water molds

• Can produce sexually and asexually
• Motile (swimming) spores
• Antheridium produces sperm
• Oogonium produces eggs

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Mutualistic relationships

• Zooxanthellae live inside coral and provide
  food through photosynthesis
• Trychonympha live in the gut of termites and
  digest cellulose