Lecture # 2 “Origin of Cells” reading: Essential Cell Biology pgs 1-15Key points of today’s lecture: 1) There is a great diversity of cell types. 2) Our descriptions and understanding of cells are completely dependent on our available tools. 3) Cells have been on Earth for a long time. 4) Self-replication is a key defining feature of cells.The first “cells” Robert Hooke, 1665Onion root tip Mammalian neuronsHuman fibroblast Frog pigment cellLargest Cell1/1,000,000 of a meter Scanning electron micrograph Mycoplasm bacteriaE. coli Paramecium Unicellular organisms (prokaryote) (eukaryote)??Origins of life??Fossil StromatolitesFossilized CyanobacteriaHow did life get started?The “RNA World” hypothesisCells todayancestral archea/bacteria ancestral photosynthetic bacteria ancestral plant cell ancestral animal cell ancestral fungal cell Why not
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