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The Origin of Eukaryotes
1. Internal membranes evolved from inward folds of the plasma membrane.
2. 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 byType of Nutrition
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
Characterized by how they move
Can be free living or parasites: Parasites live in a close relationship
with a host, and causes it harm.
Protozoans with Flagella Called Zooflagellates Most reproduce asexually Some are free living, some are
parasites
Protozoans with Pseudopodia
Pseudopodia – temporary extensions of the cytoplasm also used to surround and engulf prey
Examples: Amoeba Forams – has porous shell from which
pseudopodia extend through
Protozoans with Cilia (cilialites)
Example: Paramecium Arrangement of cilia are adapted to
different functions. 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
Paracites that don’t have a means of moving – Apicomplexans
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.
No cell wall Frequently are free living Eat organisims
Describe two functions of cilia in protozoans.
Mobility Filter water for food particles
Fungus-like protists
Slime MoldsPlasmodialCellular
Water MoldsMildews
Plasmodial Slime Molds 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 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
Have both unicellular and multicellular stages in the life cycle.
Plant-like Protists
Photosynthetic
Euglenoids
Single-celled
Posses one or two flagella
Lack a cell wall
Dinoflagellates
Unicellular
Cell wall made of cellulose
2 flagella which produce a spinning movement
Component of plankton- microscopic organisms near the surface of bodies of water.
Dinoflagellates
Impacts: Red tides Bioluminescence
Diatoms
Unicellular
Cell wall made of silica.
When they die, they sink to the bottom of the ocean forming diatomaceous earth.
Seaweeds
Multicellular Classified by the pigment they
contain Brown Algae – accessory pigments &
chlorophyll Red Algae – red pigment &
chlorophyll Green Algae – chlorophyll
Test Questions
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 Cells
Alive Reproduced
independently Cell membrane
surrounds nucleic acid
Viruses Inert Need host to
reproduce Protein coat with
nucleic acid inside
Bacteria vs. Virus
Bacteria – Reproduce independently Can be treated with an antibiotic
Virus Need host to reproduce Can be prevented using a vaccine
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