cell membrane
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true or false? cell membrane is fluid
true
true or false? a membrane is made of lipids
true
true or false? lipid heads are hydrophilic
false
true or false? lipid heads are hydrophobic
true
true or false? lipid tails are hydrophilic
true
true or false? lipid tails are hydrophobic
false
true or false? Cholestrol molecules are both polar and nonpolar
true
what does polar mean?
A structure having an uneven distribution of electron density
what is nonpolar?
A structure in which electron density is more or less evenly distributed
what are hormones madde of?
cholesterol
What do cholesterol molecules do?
• anchor phospholipids in the bilayer • keeps it from becoming too fluid at a higher temp • gives cell membrane a more defined structure
a cell membrane contains…
carbohydrates, lipids, and proteins
what do proteins do?
form chanells and pumps to help move materials
what do carbohydrates do?
• they’re attatched to the outside of the cell membrane • they act like chemical indentification, allowing cells to recognize each other
the cell membrane is selectively permeable
toxins (waste material) are pumped out
the cell membrane is self sealing
• a small tear in the bilayer creates a free edge with water • allows for the formation of vesticles to release proteins and to create new cells during cell division
the cell membrane in flexible
• at high temps: cholesterol molecules interfere with phopholipid movement and reduce fluidity • at low temps: keeps the saturated fatty acid tails from packing and mantains adequate fluidity
what is the phospholipid bilayer?
the cell membrane is arranged in two layers - extracellular - intracellular - hydrophilic tails facing each other - two rows of lipids - hydrophobic heads facing out