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Lecturer: SALMA ALRDAHE. Cell Membrane 4 th lab. Cell Membrane. The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. Cell membrane under microscope. Cell membrane under microscope.
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Lecturer: SALMA ALRDAHE Cell Membrane4th lab
Cell Membrane The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment
Functions of Cell Membrane • It surrounds the cytoplasm of animal and plant cells, physically separating the intracellularcomponents from the extracellular environment. • The membrane is selectively permeable and able to regulate what enters and exits the cell. • The movement of substances across the membrane can be: • either "passive", occurring without the input of cellular energy, • or active, requiring the cell to expend energy in transporting it.
Cell membrane employs a number of transport mechanisms: • 1. Passive diffusion and osmosis: Some substances (small molecules, ions) such as (CO2), (O2), and water, can move across the plasma membrane by diffusion • (passive transport process). • 2. Transmembrane protein channels and transporters: Nutrients, such as sugars or amino acids, must enter the cell, and certain products of metabolism must leave the cell.
Cell membrane employs a number of transport mechanisms: • 3. Endocytosis: Endocytosis is the process in which cells absorb molecules by engulfing them. • Endocytosis requires energy (active transport). • 4. Exocytosis: the membrane of a vesicle can be fused with the plasma membrane, extruding its contents to the surrounding medium. • Exocytosis occurs to: • remove undigested residues of substances • secrete substances such as hormones and enzymes.