Cell Membrane Structure and Function

Membrane Design fluid-mosaic model a. Fluid = pliable/easily moved Cell Membrane Animation fluid-mosaic model a. Fluid = pliable/easily moved b. Mosaic = made of many different molecules (lipids, proteins, carbohydrates)

Selectively Permeable Predict the two reasons things can’t directly go through the membrane: Size (duh) Polarity (from last unit)

Selectively Permeable The cell membrane only lets certain substances in and out of the cell

Phosopholipid Bi-Layer -polar heads are hydrophilic “water loving” -tails (fatty acids) are hydrophobic “water fearing” and face inward

Cholesterol Type of steroid (lipid) Changes fluidity of cell membrane Higher temps – stiffens membrane Lower temps – prevents membrane from freezing

Proteins Recognition Proteins Receptor Proteins Proteins that have carbohydrate chains attached Carbohydrate chains aid in cell identification “Name Tags” Example: Red Blood Cells (A, B), Identify Viruses as foreign Receptor Proteins Proteins that receive chemical signals from other cells Such as nervous system cells

Proteins Channel Proteins Proteins that involved in letting certain substances in and out of cells Aquaporins- let water in and out of cells

Proteins Integral Peripheral Proteins that cross both layers of the phosphoplipid bilayer Peripheral proteins that are only on the top half or bottom half of the phospholipid bilayer