BIO 1030 Lecture Notes - Lecture 7: Cytoplasm, Cell Theory, Electron Microscope
30 Jan 2017
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Document Summary
Cells: are extremely diverse, nearly all require a microscope to be seen, each type in our body is specialized for a particular function. Invented in 17th century: limited by properties of light. Invented in 1930s: overcomes limitation by using beam of electrons. Why are cells so small: need surface areas large enough for entry and exit of materials, surface-area-to-volume ratio, small cells have more surface area for exchange, adaptations to increase surface are. Microvilli in the small intestine increase surface area for absorption of nutrients. Plasma membrane: marks boundary between outside and inside of a cell, regulates passage in and out of a cell, phospholipid bilayer with embedded proteins. Polar heads of phospholipids face into watery medium. Form tunnel for specific molecules: transport proteins. Involved in passage of molecules through the membrane. Sometimes requires input of energy: cell recognition proteins. Enable our body to distinguish between our own cells and cells of other organisms: receptor proteins.
