Ch. 5-1
Homeostasis and the plasma membrane

maintain homeostasis even though the external environment is constantly changing
selectively & actively permeable
	moving materials in/out of cell
	2 ways:
		Passive transport
			no cell energy used
			cell can be alive/dead
		Active transport
			requires cell energy(ATP)
			has to be alive
Structure of the plasma membrane
	Phospholipid
		phosphate head
			polar
			negative charge
			hydrophilic
		fatty acid tails(2)
			non-polar
			hydrophobic
		glycerol
			triose (3-carbon sugar)
			"backbone"
	Membrane proteins
		2 groups
			peripheral ("edges")
				inside/outside
				not embedded
			integral ("part of")
				embedded in phospholipid bilayer
				important in active transport
	Cholesterol
		keeps membrane fluid
		type of steroid
		prevents tangles in membrane
Through membrane or through protein
	Fat Soluble
		non-polar
		dissolve through membrane "fast"
	Most other things go through proteins
Fluid Mosaic Model
	lipid bilayer flows like vegetable oil







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