Answer:
<u>O floating around one another in a fluid structure</u>
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Explanation:
Cells are made up of varying types of molecules in order to achieve a fluid, stable plasma membrane. The membrane mainly consists of:
- lipids
- proteins
- cholesterol
Lipid membranes help maintain selective membrane permeability. The lipids, formed from glycerol and saturated/unsaturated fatty acids, are made up of polar heads and non-polar tails; they typically only allow the movement of <em>small non-polar molecules</em>. Larger molecules are <em>transported </em>through integral proteins; other types, are peripheral, and may have specialized functions like <em>cell signaling</em>.
Cholesterol molecules keep the lipids in place, and ensure membrane fluidity. In extreme temperatures, they help the membrane to maintain its shape without becoming too rigid.