Protists

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Protists

• Unit 6
• Chapter 19

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Protist characteristics

• Eukaryotic having organelles and nucleus
• Unicellular or multicellular
• Heterotrophic, autotrophic, or saprobic
• Microscopic or large
• Divided into three major groups protozoans,
  algae, and fungus-like protists

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Protozoans animal-like protists

• Heterotroph consume organic matter
• Unicellular

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Algae plant-like protists

• Autotroph uses light to make sugars through
  photosynthesis
• Lack roots, stems, and leaves

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Fungus-like protists

• Decompose dead matter
• Motility during some stage of life cycle
• No chitin in cell walls

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Protist-borne diseases

• Malaria
• Sleeping sickness

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Helpful protists

• Algae through photosynthesis produce oxygen, that
  makes up the ozone layer.
• Algae and protozoans can also be part of the
  plankton that feeds marine animals.
• Fungus-like protists decompose matter and returns
  nutrients back to the soil.

plankton
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Protist reproduction

• Mostly asexual requiring one source of DNA for
  offspring
• Sometimes sexual requiring two sources of DNA
  for offspring

Freshwater algae asexually reproducing
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Protozoans

• Animal-like protists

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Major groups of protozoans

• Amoeba
• Flagellate
• Ciliate
• Sporozoan

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Movement with pseudopods

• Pseudopod false foot

Amoeba, shapeless cells
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Feeding with pseudopods
The extensions of the cellular body surround food
particles, which the amoeba then draws into
itself for digestion.
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Other amoeboid protozoans
foraminiferans
radiolarians
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Movement with flagella

• This disease causing Giardia protozoan has
  flagella to move around.

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Flagellates whip their tails back and forth to
propel the cell.
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Movement with cilia

• Note the fine cilia that surround the paramecium,
  making a halo glow.

Notice the starburst shaped organelle, the
contractile vacuole that helps to pump out excess
water.
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Sporozoans parasitic protozoans

• Disease causing
• Produces spores within host cell
• Spore reproductive cell that forms without
  fertilization and produces a new organism

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Plasmodium, cause of malaria

• The protist is transmitted through a mosquito
  bite to a human host.
• The protist reproduces inside the human red blood
  cells, making them puckered and unable to carry
  oxygen to the body.

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Malaria life cycle
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Algae

• Plant-like protists

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Algae pigmentation

• All have chlorophyll
• Some have other pigments purple, rusty-red,
  olive-brown, yellow, and golden-brown.
• Algae are grouped according to their pigmentation.

Ex green algae
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Major groups of algae

• Euglenoid
• Diatom
• Dinoflagellate
• Green algae
• Red algae
• Brown algae

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Euglenoids

• Unicellular
• Aquatic
• Animal-like
• Plant-like photosynthetic
• No cell wall, just tough cell membrane
• Flagella

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Euglenoid
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Diatoms golden algae

• Shells made of silica (major component of glass)
• Carotenoid pigment
• Unicellular
• Photosynthetic
• Various shapes
• Oily inside

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Diatoms
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Uses of diatoms, dredged from ocean floors

• abrasives in tooth and metal polishes
• added to paint to give the sparkle that makes
  pavement lines more visible at night

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Dinoflagellates

• Many pigments
• Two flagella at grooves
• Bioluminescent emit light
• Symbiotic relationship with jellyfish
• Produce toxins

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Red tide

• Concentration of nerve toxins from certain
  dinoflagellates cause water bodies to appear red.
• This water and contaminated shellfish can make
  humans sick.

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Red algae

• Multicellular
• Commonly called seaweed
• Thallus Seaweed body that attaches to a surface
• Found deep in the ocean because they can use the
  light that filters to the bottom for
  photosynthesis

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Red algae
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Brown algae

• Mostly multicellular
• Mostly in cool, marine waters
• Air bladders in thallus keeps the algae floating

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Kelp forests

• Dense growth of brown algae
• Habitat for many marine animals

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Green algae

• Most diverse
• Chlorophyll-rich
• Can grow anywhere, even in fur of sloth (below)

Colonial algae called Volvox
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Unicellular green algae
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Multicellular green algae
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Fungus-like protists

• slime molds, water molds, and downy mildews

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Slime molds most like true fungus

• Cool, moist environments
• Able to move around to feed during most of the
  life cycle
• Two major types

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Water molds and downy mildews
Fuzzy white growth on decaying matter
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How water molds and downy mildews feed

• They grow long extensions over the organic
  material and absorb nutrients through their cell
  membranes.
• A particular species infected the Irish potato
  crop and caused a large famine.