Lecture 2 & 3 introducion to cell biology. What is a cell: cell theory. The basic structural and funcional unit of all life forms. Name the diferent organelles and the roles/funcions for each: cells are enclosed by a plasma membrane and contain cytoplasm within (cytosol and organelles, cytosol composed of the cytoskeleton (made up of ilaments, plasma membrane. Phospholipid bilayer 2 phospholipid molecules thick. Barrier between external and internal environment transport of material across it surface. What are the diferent scales/sizes for cells and organelles: eukaryotes are much larger than prokaryotes. 1nm = 10-9 m: scale in biology (smallest to largest in size) Length of some nerve/muscle cells 1 m. Explain the theory of the cell and endosymbiosis: endosymbiosis iniiated when an anaerobic bacterium engulfed an aerobic bacterium (prokaryotes, instead of swallowing the aerobic bacterium it becomes a part of the anaerobic bacterium.