The Plasma Membrane Section 7.2 p.175-178. Maintaining a Balance All living cells must maintain a...
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Transcript of The Plasma Membrane Section 7.2 p.175-178. Maintaining a Balance All living cells must maintain a...
![Page 1: The Plasma Membrane Section 7.2 p.175-178. Maintaining a Balance All living cells must maintain a balance regardless of internal + external conditions.](https://reader030.fdocuments.in/reader030/viewer/2022032722/56649f425503460f94c61305/html5/thumbnails/1.jpg)
The Plasma MembraneSection 7.2p.175-178
![Page 2: The Plasma Membrane Section 7.2 p.175-178. Maintaining a Balance All living cells must maintain a balance regardless of internal + external conditions.](https://reader030.fdocuments.in/reader030/viewer/2022032722/56649f425503460f94c61305/html5/thumbnails/2.jpg)
Maintaining a Balance• All living cells must maintain a balance
regardless of internal + external conditions• Survival depends on the cell’s ability to
maintain proper conditions within itself
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Why cells must control materials• Cells need nutrients
to function– Glucose– Amino acids– Lipids
• Must enter through the plasma membrane– The flexible boundary
between the cell + its environment
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Why cells must control materials• Substances such as wastes + products must
leave through the plasma membrane– Substances enter + leave to maintain homeostasis– Selectively permeable• Ability to allow some molecule to pass through while
keeping others out– Examples
» Water vs. Na+ ions
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Selectively Permeable
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Structure of the Plasma Membrane
• Recall – LIPIDS (Fatty Acids + glycerol)
• Phospholipid– Two fatty acids, glycerol, + a
phosphate group• Plasma membrane is
composed of a phospholipid bilayer
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The Phospholipid bilayer• Fatty acids “tails” are hydrophobic
– Don’t want to interact with water• Phosphate group “head” is hydrophilic
– Wants to interact with water
• Creates a barrier that regulates the ease in which substances cross the plasma membrane
![Page 8: The Plasma Membrane Section 7.2 p.175-178. Maintaining a Balance All living cells must maintain a balance regardless of internal + external conditions.](https://reader030.fdocuments.in/reader030/viewer/2022032722/56649f425503460f94c61305/html5/thumbnails/8.jpg)
Fluid Mosaic Model• The proteins embedded in the bilayer create the
“mosaic”• The phospholipids move within the membrane
(like a fluid)
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Other components of the P.M.• Cholesterol– Helps to stabilize the phospholipids by preventing
their FA’s from sticking together
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Other components of the P.M.• Proteins
– Transport• Move substances through PM
– Markers• Identify chemical signals + each other
– Inner surface• Gives cell’s structure flexibility