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Unformatted text preview: 1 Composition of Cells Lecture 08 Esther Angert Cornell University Cytology - The Biology of the Cell 1. Scale of Life and the Cell 2. Using Microscopy and Biochemistry 3. Prokaryotic vs. Eukaryotic cells *Fundamental similarities *Fundamental laws 4. Parts of the Bacterial Cell 5. Parts of the Eukaryotic Cell endomembrane system additional organelles cytoskeleton Cellular life, not viruses Bacteriophage = phage 0.5 µ m (500 nm) 100 nm The scale of life… • Organisms range in mass (size) over 21 orders of magnitude – From the smallest microbes that weight <10-13 g (0.1 picogram) to… – Largest mammals (blue whale) and plants (giant sequoia) that may weigh 10 8 g – All are composed of cells 0.5 µ m Mycoplasma pneumonia Sequoiadendron giganteum Balaenoptera musculus “ARMAN” nanoorganism • Most cells fall within a fairly narrow size range • To survive, cells must exchange molecules with their environment • Exchange velocity is directly related to the cell surface area relative to its volume (review & understand Fig 6.7 in text) • There are exceptions … Thiomargarita 750 µ m Caulobacter cescentus • Bacterium that inhabits low nutrient, freshwater environments • When starved for phosphate, its stalk grows longer to increase its surface area stalk 2 We use this strategy too… • Intestinal epithelial cells absorb nutrients from the food we eat • Microvilli increase surface area • Eukaryotic cells are generally larger than prokaryotic cells (bacterial & archaeal cells) • Eukaryotic cells have membrane- bound, subcellular compartments to organize cellular functions Prokaryote vs. Eukaryote • Nucleoid (not membrane bound) • Generally, these are small, simple looking cells when compared to a eukaryotic cell • Bacteria + Archaea • Paraphyletic group consists of ancestor and some but not all of its decedents (not nested) • Nucleus • Complex subcellular structure (membrane- bound compartments) Bacteria Archaea Eukarya Microscopy and Biochemistry • Microscopy: Study cellular organization...
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This note was uploaded on 10/13/2009 for the course BIO G 1101 taught by Professor Gilbert during the Fall '07 term at Cornell.
- Fall '07