BIO 202 Lecture Notes - Lecture 2: Mollusca, Dinos, Charales
Document Summary
Eukaryotes have two organelles with multiple membranes. This is because eukaryotes evolved from a combination of an archaean who developed a nucleus and a bacteria that got incorporated into it. Ancestral chloroplasts found in red algae, the oldest known algae group. Phycobilisomes (made of phycobilins) found on the outer side of the membrane of thylakoids. The ancestral red algae cell engulfed a bacteria. The bacteria has its own membrane, and the ancestral red algae engulfed it by wrapping it in a vacuole = 2 membranes. The primary endosymbiotic event created 2 membranes around chloroplasts. Green algae lost phycobilisomes and evolved grana (thylakoids in stacks) The 4 membrane chloroplasts were created when a eukaryotic cell was endocytosed within another cell. (2 membranes from chloroplast, 1 from engulfed cell membrane, and one from the vacuole = 4) The outer membrane of the chloroplast became continuous with the outer nucleus. The inner nucleus was lost, resulting in the 4-membrane form we see today.
