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BIO 1011 Dr. Lee Science Center 227 Phone: (610) 660-3439 [email protected] Levels of Biological Organization What is a cell? Discovered by Robert Hooke, 1655 Microscopic Analysis of cork sections Tiny “Chambers” = “Cells” QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Wikipedia What is the “Cell Theory”? • Cells are the universal building blocks of life • Cells arise from pre-existing cells What defines something as “living”? How big is a cell? A Sense of Scale Figure 1-6 01_06_What can we see.jpg “What can we see?” “What can we see?” Metric Units • • • • • • • One meter - About Three Feet One mm - 1/1000 of a meter One µm - 1/1,000,000 of a meter One nm - 1/1,000,000,000 of a meter mm = 10-3 m µm = 10-6 m nm = 10-9 m How to look at cells • Light microscopy • Electron microscopy How to look at cells • Light Microscopy – Resolution of about 0.2 m • Resolution - How close two objects can be together and still be seen as 2 objects Light Microscopy Fixed and stained Live cell The History of Cell Visualization: Eduard Strasburger, 1880: 01_04_Early microscopes.jpg Modern day light microscopy: How to Look at Cells • Electron Microscopes • Two types: – Scanning • 3-D image of cell’s surface • Resolution of 3 nm – Transmission • Interior cell structure • Resolution of 2 nm • Higher resolution because of shorter wavelength SEM of a protozoan (single celled eukaryote) Fig. 1-32 TEM micrograph of a killer T cell preparing to attack a large tumor cell TEM Micrograph of Mammalian Cell Basic Cell Anatomy Basic Cell Anatomy Plasma Membrane Cytoplasm (cytosol: soluble portion) Two major cell types Prokaryotic Eukaryotic A Basic Distinction: Prokaryotic and Eukaryotic Cells “Pro” = before “Eu” = true Distinguishing features: The world of prokaryotes: Eubacteria and Archaea The diversity of prokaryotes The common bacterium: Escherichia coli (E. coli) Cells range in sizes Flagellum Ribosomes in cytosol DNA Plasma Membrane Cell wall Panel 1-2 Plant vs animal vs bacterial cell size The Eukaryotic Cell: Nucleus Mitochondria (chloroplasts) Internal Membranes generate intracellular compartments ER Golgi Lysosomes Peroxisomes Vesicles Cytosol Cytoskeleton Miniature Factory Engine Fig.1-5 Key concepts you need to know • Unity within Diversity • The role of microscopy in cell visualization Panel 1-1, Page 8 (basics) • The fundamental basis of cell classification Eukaryotic and Prokaryotic • The subcellular components of the eukaryotic cell PANEL 1-2, Page 25
