BIOL 111 Lecture Notes - Lecture 13: Photosystem Ii, Red Algae, Photosystem I
30 Oct 2018
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A note about taxonomy & bias: in his 1735 classification system for nature, linnaeus has three kingdoms: plants, animals, and stones. 1969- monera (essentially bacteria) but archaea weren"t discovered until 1970s. Where are the photosynthesizers? (top left) branches with photosynthetic organisms red algae, green algae, streptophytes. A mega key innovation first evolved ca. 3 billion years ago, by a bacteria --> cyanobacteria, --- Clue 2: photosystem i and photosystem ii evolved in bacteria. Endosymbiotic origin of chloroplasts- hypothesis: eukaryotic chloroplast originated when a protist engulfed a cytoplasm. How did chloroplasts spread to 4/5 major eukaryote lineages: all species in plantae have chloroplasts, plantae chloroplasts have double membrane, plantae engulfed green algae, photosynthetic protist is engulfed, nucleus from photosynthetic protist is lost, organelle has four membranes. Common ancestor, multiple time evolution neither, got subsumed by additional organisms. Brown algae (phaeophytes)- ending phyte = plantish: chloroplast with 4 membranes, 1500 to 2000 species, multicellular marine organisms.
