BIOL208 Lecture Notes - Lecture 12: Tangled, Transposable Element, Algae
29 Mar 2018
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Document Summary
The oldest fossils of eukaryotic cells date back to ~1. 8 bya (~2 billion years after prokaryotes) Photosynthetic cyanobacteria caused "oxygen revolution" from 2. 7-2. 3 bya. Eukaryotic cells arose a few hundred million years after the oxygen revolution. Eukaryotic cells differ from prokaryotic cells in several ways: Dna in linear chromosomes in membrane bound nucleus: eukaryotic genomes are larger than those of prokaryotes, allowing for evolution of new mechanisms of gen regulation. Compartmentalizing machinery for energy metabolism frees the cell to interact wit the environment in novel ways not available to prokaryotes. Often much larger than prokaryotes, but not invariably. Cytoskeleton: (internal network of proteins) allows them to change shape, move, and transfer substances in and out of the cell (e. g. to engulf particles by phagocytosis) Eukaryotic cells have dynamic membranes that facilitate movement and feeding (e. g. phagocytosis) Sexual reproduction promotes genetic diversity in eukaryotic populations. Meiosis: creates unique gametes (chromosome recombination; independent assortment of alleles)
