34 lines
2.2 KiB
Markdown
34 lines
2.2 KiB
Markdown
[[Cell Structure and Function]]
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# Summary
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* Phospholipids are amphipathic (both hydrophobic and hydrophilic): hydrophilic phosphate heads point towards water hydrophobic fatty acid tails point away.
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* Embedded proteins have hydrophilic regions facing the cytosol or extracellular fluid. Also have hydrophobic regions that contact the fatty acid tails in membrane interior.
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* Cholesterol (in vertebrate animals) acts as a fluidity buffer, preventing the membrane from getting too loose or stiff in head or cold.
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* Fluid mosaic model describes a membrane with phospholipids, proteins, cholesterol, glyco(proteins/lipids) can move around the surface.
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* Fatty acid affects fluidity, unsaturated with kinks increases it, while saturated makes the phospholipids pack tightly together.
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* Glycoprotein and glycolipid sit on the outside and help with cell recognition.
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Plasma membrane defines the edge of every cell, it's not a wall and is flexible.
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# Components of the Plasma Membrane
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Phospholipids are main structural framework as a bilayer. Hydrophobic fatty acid tails point away from aqueous environment, hydrophilic phosphate heads point towards.
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Steroids (cholesterol in vertebrates) restrain phospholipid movement at high temps and prevents them from packing tightly at low temps.
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Gylco(proteins/lipids) are carbohydrates, attached to proteins and lipids, helps cells recognize each other.
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# Fluid Mosaic Model
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Describes the plasma membrane as structural framework of phospholipids embedded with proteins, steroids(cholesterol) and glyco(steroids/lipids). Describes them as being able to move freely.
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Fluid nature, phospholipids can move laterally like they're in a sea of lipids. Allows components to shift and form regions for different jobs.
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Variety of molecules creates a mosaic appearance, thus the name.
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# Factors Affecting Membrane Fluidity
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* Temp
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* Fatty acid composition (look below)
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* Cholesterol content (look above)
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# How Structure Connects to Function
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Hydrophobic interior blocks polar molecules while allowing small non-polar molecules pass more freely. Basis for selective permeability.
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Embedded proteins allow for specific interactions. Receptor proteins bind to signaling molecules, transport proteins move them. |