Protists

Unicellular eukaryotes

Origin of Eukaryotes

Endosymbiosis: theory that explains how eukaryotic cells evolved from the symbiotic relationship between two or more prokaryotic cells

one cell engulfs a different type of cell, however the engulfed cell survives and becomes an internal part of the engulfing cell

prokaryotes lack many internal structures, where eukaryotes are very complex with multiple membrane-bound organelles

believed that the organelles used to be free-living prokaryotes

2 major organelles that provide the strongest evidence for endosymbiosis: chloroplast and mitochondria

chloroplast converts solar energy into sugarmitochondria extracts energy stored in sugar

for cell to useother evidence for theory: membranes of

mitochondria and chloroplasts are similar to those of living prokaryotesthese organelles reproduce by binary fission

within the cellthey also contain a circular chromosome where

many sequences match those of living prokaryotes

Multicellularity

hypothesized that first multicellular organisms arose from colonies created by dividing individuals cells

genes within these cells contained instructions for some cells to become specialized for different functions

increased specialization made it possible for different functions to develop among different groupings of cells in multicellular organisms

Life Cycles and Reproduction

prokaryotes reproduce asexually, so do unicellular eukaryotes

reproduction of multicellular individuals is typically sexual reproduction

Characteristics of Protists

eukaryotesnot quite plants, animals or fungican be unicellular, free-living, colonial or

multicellularcontain a typical eukaryotic cell with

organellessome have chloroplasts photosynthesis

Theory

plants, animals and fungi evolved from protists

Movement

 pseudopodia – cellular extensions of streaming cytoplasm that allow organisms to move

http://www.youtube.com/watch?v=7pR7TNzJ_pA&feature=fvw cilia – hair like structures flagella – tail like structures

http://www.youtube.com/watch?v=QGAm6hMysTA spores: protists who can’t move release

reproductive cells that enter bodies and act as a parasite

e.g. apicomplexan, plasmodium (malaria)

Reproduction

binary fission amoeba, paramecium, ciliates

conjugationsexual and asexual reproductionPlasmodium reproduces asexually in

humans but sexually in mosquitos

Animal-like protists

(Amoebas, ciliates and flagellates)heterotrophs: capture and ingest food forms internal food vacuole and digests

foodsome species are parasites

http://www.youtube.com/watch?v=ojrkxmD6tT8&feature=related

Amoeba

Trichomonas foetus : cow disease

Trichomonas vaginalis: an STD

Paramecium

Termite Gut Bacteria

Malaria in red blood cells

Fungus-like protists

(slime moulds and water moulds)heterotrophs that feed mostly on decaying

organic mattersome slime moulds consume other

organismssome water moulds are parasites

Slime Moulds In Action

https://www.youtube.com/watch?v=bkVhLJLG7ug

https://www.youtube.com/watch?v=GY_uMH8Xpy0

https://www.youtube.com/watch?v=czk4xgdhdY4

Plant-like protists

(euglenoids, diatoms and dinoflagellates)contain chloroplasts for photosynthesisalgae: autotrophs that make their own foodphytoplanktonsome consume other organisms when

light is unavailable

http://www.ucmp.berkeley.edu/chromista/diatoms/centriclive.jpg

Red Tide