Ch. 4-6
Cell Membrane


cell cannot survive completely isolated
	must take in nutrients
	dispose of wastes
Selectively permeable
	not everything can pass through
Structure
	depends on function cell performs
Made of
	Lipids
		phospholipid
			polar head
			2 non-polar tails
				form lipid bilayer
					heads point out
					tails face in
		steroids
			i.e. in animals-cholesterol
	Membrane Proteins
		peripheral proteins
			attached to surface of cell membrane
		integral proteins
			embedded in bilayer
				often have carbs. attached
				hold adjoining cells together
				sites where...can attach
					viruses
					chemical messengers
						i.e. hormones
		some form pores for substances to pass through
Fluid Mosaic model
	membranes are very dynamic
	used to describe cell membrane






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