01:119:115 Lecture Notes - Lecture 5: Nuclear Membrane, Vascular Tissue, Archaea
15 Oct 2018
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Document Summary
A hypothesis for the origin of eukaryotes through serial endosymbiosis. Serial endosymbiosis supposes that mitochondria evolved before plastids (chloroplasts) through a sequence of endosymbiotic events. Key evidence supports an endosymbiotic origin for mitochondria and plastids: Double membrane organelles with inner membranes similar to plasma membranes of prokaryotes (enzymes and transport mechanisms) Organelles divide (split), transcribe and translate their own circular dna; structurally similar to prokaryotes. Their ribosomes are closer to prokaryotic than eukaryotic in characteristics: including sensitivity to antibiotics like streptomycin. The evolution of eukaryotic cells allowed for a greater range of unicellular forms. Red algae- first multicellular 1. 2 billion years. The ediacaran organisms that followed were larger, more diverse and included soft- bodied animals living from 575 to 535 million years ago. sponges, cnidarians, and molluscs. Fossils resembling modern animal phyla arose in the. Cambrian period (535 525 million year ago) The cambrian explosion provided the first evidence of predator-prey interactions.
