Transcript Chapter 17 - Protists

The Origin of Eukaryotes
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Internal membranes evolved from inward
folds of the plasma membrane.
Endosymbiosis – chloroplasts and
mitochondria evolved from prokaryotes
that lived within a larger host prokaryotes.
Protists
Eukaryotes that are not animals,
plants or fungi.
Grouping Protists by
Type of Nutrition
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Animal-like: heterotrophs (protozoans)
– ingest food
Fungus-like: heterotrophs – feed on
decaying organic matter.
Plant-like: autotrophs (algae) make
their own food by photosynthesis
Protozoans
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Characterized by how they move
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Can be free living or parasites:
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Parasites live in a close relationship with a
host, and causes it harm.
Protozoans with Flagella
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Called Zooflagellates
Most reproduce asexually
Some are free living, some are parasites
Protozoans with Pseudopodia
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Pseudopodia – temporary extensions of
the cytoplasm also used to surround
and engulf prey
Examples:
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Amoeba
Forams – has porous shell from which
pseudopodia extend through
Protozoans with Cilia
(cilialites)
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Example: Paramecium
Arrangement of cilia are adapted to different
functions.
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Many cilia joined together work to aid movement
Cilia rings around the mouth aid in the uptake of
food.
Can produce sexually or asexually.
Have two types of nuclei.
Protozoans Lacking Motility
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Paracites that don’t have a means of moving –
Apicomplexans
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The apical complex is a structure on the tip of
the cell that helps for penetrating host cells.
Describe two "animal-like"
characteristics of protozoans.
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No cell wall
Frequently are free living
Eat organisims
Describe two functions of cilia
in protozoans.
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Mobility
Filter water for food particles
Fungus-like protists
Slime Molds
Plasmodial
Cellular
Water Molds
Mildews
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Plasmodial Slime Molds
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Unicellular
Plasmodium – single mass of
cytoplasm undivided by
membranes & containing many
nuclei
Extend pseudopodia to engulf
bacteria & organic matter.
Cytoplasmic streaming to
distribute nutrients and oxygen
throughout the organism.
Plasmodial Slime Molds
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When food and water are scarce, sporangia develop.
Tips of sporangia produced spores that can be
dispersed by wind.
In favorable conditions the
spores release haploid cells that
unite forming zygotes.
Cellular Slime Molds
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Have both unicellular and multicellular
stages in the life cycle.
Plant-like Protists
Photosynthetic
Euglenoids
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Single-celled
Posses one or
two flagella
Lack a cell wall
Dinoflagellates
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Unicellular
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Cell wall made of cellulose
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2 flagella which produce a spinning movement
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Component of plankton- microscopic organisms
near the surface of bodies of water.
Dinoflagellates
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Impacts:
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Red tides
Bioluminescence
Diatoms
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Unicellular
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Cell wall made of silica.
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When they die, they sink
to the bottom of the ocean
forming diatomaceous
earth.
Seaweeds
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Multicellular
Classified by the pigment they contain
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Brown Algae – accessory pigments &
chlorophyll
Red Algae – red pigment & chlorophyll
Green Algae – chlorophyll
Test Questions
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RNA was believed to be the first nucleic
acid because it can copy itself in small
pieces without the aid of enzymes.
Cells vs. Viruses
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Cells
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Alive
Reproduced
independently
Cell membrane
surrounds nucleic
acid
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Viruses
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Inert
Need host to
reproduce
Protein coat with
nucleic acid inside
Bacteria vs. Virus
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Bacteria –
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Reproduce independently
Can be treated with an antibiotic
Virus
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Need host to reproduce
Can be prevented using a vaccine
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Transformation – Bacteria pick up
pieces of DNA from the environment
Conjugation – two cells join and
transfer genetic info between them
Transduction – Viruses infect bacteria
carrying genes from one cell to the next
Reproduction of a Virus