Membrane Transport Flashcards
What is the primary function of the cell membrane in multicellular organisms?
determines the nature of its contact with the environment, allowing the cell to exclude some substances, take in others, and excrete others
What are the main components of the cell membrane according to the Fluid Mosaic Model?
phospholipids, cholesterol, proteins, and carbohydrates.
Describe the arrangement of phospholipids in the cell membrane.
arranged in a bilayer, with their hydrophilic polar heads facing the water-based intracellular and extracellular fluids, and their hydrophobic fatty acid tails pointing towards each other at the interior of the membrane.
What roles do integral and peripheral proteins play in the cell membrane?
Integral proteins are embedded in the plasma membrane and may span all or part of the membrane, serving as channels, gates, or pumps to move materials into or out of the cell. Peripheral proteins are found on the exterior or interior surfaces of membranes, attached either to integral proteins or phospholipid molecules.
What is the glycocalyx, and what is it composed of?
carbohydrate-rich area on the exterior surface of the cell, composed of carbohydrate chains bound to proteins (glycoproteins) or lipids
Which types of molecules can easily pass through the hydrophobic core of the membrane?
CO2 and O2, which have no charge, can easily pass through the hydrophobic core of the membrane.
Why can’t polar substances and charged molecules pass easily through the cell membrane?
it repels hydrophilic and charged substances.
What is diffusion, and how does it occur?
passive process where a substance displays a net movement from an area of high concentration to an area of low concentration until equilibrium is reached
hat is osmosis, and how does it differ from diffusion?
water across a selectively permeable membrane, following its concentration gradient
What is tonicity, and how is it related to osmolarity?
describes the amount of solute in a solution, while osmolarity measures the total amount of solute dissolved in the solution. Tonicity relates the osmolarity of a cell to the extracellular fluid.
What is exocytosis, and how does it function in a cell?
expelling material from the cell into the extracellular fluid. A particle surrounded by a vesicle fuses with the cell membrane, causing the contents to be emptied from the cell.
