Download Cell Membrane Structure

Cell Membrane Structure
Phospholipids
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Hydrophilic Head made of Phosphate
2 Hydrophobic Tails made of Fatty Acids
Makes up the majority of the membrane
Mobile, not fixed in one place
Phospholipid Bilayer
• 2 layers of Phospholipids turned tail to tail
• Semipermeable (selectively permeable)
– Picky about what can move across the membrane
– Only allows certain things through
• Fluid Mosaic = made of many different parts
that are not stuck in one spot
Cholesterol
• Adds strength, structure, and stability to the
membrane
• Decreases the phospholipids range of motion
Proteins
• Protein Channels
– Passively allow large molecules through the
membrane that cannot get past the phospholipids
• Protein Pumps
– Force molecules through the membrane against
the concentration gradient
• Structural
– Provide strength, support, and sites for
attachment
Carbohydrate Chains
• Identification of cells
• Communication between cells
• Always on the outside of the cell (outer
membrane layer)
OUTSIDE
OF CELL
INSIDE OF
CELL
Concentration
• Solute = substance being dissolved
• Solvent = substance doing the dissolving
• Concentration = the amount of solute in a
solution
• Concentration is the referring to the DENSITY
• Density = how crowded the molecules are
Mass/Volume
Hypertonic
• Hypertonic Solution = MORE DENSE than the cell
• “above strength”
• More Solutes & Less Water in the solution
OUTSIDE the Cell compared to the cytoplasm
• Water Moves OUT of the cell
• Cell SHRINKS
Hypotonic
• Hypotonic Solution = LESS DENSE than the cell
• “below strength”
• Less Solutes & More Water in the solution
OUTSIDE the Cell compared to the cytoplasm
• Water Moves INTO the cell
• Cell SWELLS & may BURST
Isotonic
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Isotonic Solution = SAME DENSITY as the cell
“same strength”
EQUILIBRIUM
The solution OUTSIDE the cell has an equal
concentration of solutes and water compared to the
cytoplasm
• Water Moves IN & OUT of the cell at the SAME RATE
• Cell STAYS THE SAME