Summary Nelson Biology 11 - 2.3 - The Protists

‭2.3 The Eukaryotes: Kingdom Protista‬
-‭ ‬ ‭ irst eukaryotes‬
F
‭-‬ ‭Most aquatic, some terrestrial‬
‭-‬ ‭Extremely diverse: small unicellular → giant multicellular (green kelp)‬
‭-‬ ‭Asexual/sexual reproduction‬
‭-‬ ‭Many are‬‭parasites — live on other organisms‬‭: some are not harmful, others cause disease‬



‭IMPORTANCE‬
-‭ ‬ ‭ hotosynthetic protists‬‭: major producers in the ocean‬
P
‭-‬ ‭Non-photosynthetic protists:‬‭consumers who dominate the lowest trophic level‬
‭-‬ ‭Some protist parasites are harmful to their hosts —‬‭malaria (caused by plasmodium) →‬‭greatest‬
‭concern for humans, sleeping sickness, amoebic dysentery, giardiasis (intestinal parasite)‬
-‭ ‬ ‭Food products: nori in sushi, food additive (carrageenan), seaweed (toothpaste, cosmetics, paints)‬
‭-‬ ‭Agar‬‭: a gelatinous substance derived from red algae → used as culture medium for growth of‬
‭bacteria‬



‭The Origins of Eukaryotes‬
‭ )‬ E
1 ‭ volution‬‭from prokaryotic to eukaryotic‬‭cells‬
‭-‬ ‭Internal organelles developed when a ancestral prokaryotic cell membrane folded in on itself‬
‭-‬ ‭Prokaryote becomes eukaryote‬

‭ )‬ O
2 ‭ rigin of‬‭mitochondria‬‭and‬‭chloroplasts‬‭:‬‭Endosymbiosis‬
‭-‬ ‭Consider: mitochondria & chloroplasts each have 2 membranes‬
‭-‬ ‭Inner membranes similar to those of ancestral prokaryote‬
‭-‬ ‭Outer membranes match eukaryotic cell membranes‬
‭-‬ ‭Mitochondria & chloroplasts have their own chromosomes → similar to prokaryotic‬
‭chromosomes, contain genetic info used by organelles‬
‭-‬ ‭Mitochondria & chloroplasts‬‭reproduce independently‬‭within eukaryotic cells by‬‭binary‬
‭fission‬‭as prokaryotes do‬
‭-‬ ‭Mitochondria & chloroplasts are thought to originate by‬‭Endosymbiosis‬

‭→ Theory:‬
‭-‬ ‭Mitochondria → aerobic prokaryote‬
‭-‬ ‭Chloroplasts → photosynthetic prokaryote‬
‭-‬ ‭provide benefit for eukaryotes : glucose‬
‭-‬ ‭benefit from eukaryotic cell: CO‬‭2‬ ‭produced‬
‭- Endosymbiosis is widespread: beneficial / parasites‬

,