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Cells Review 2

Cell membrane and transport

QuestionAnswer
What is another name for the cell membrane? Hint: think of what makes it up. The phospholipid bilayer.
Which part of a phospholipid is hydrophobic? Hydrophilic? The head of a phospholipid is hydrophilic. The fatty acid tails of the phospholipid are hydrophobic.
Why is the plasma membrane also called a 'fluid mosaic'? Because it is made up of many different proteins and lipids (mosaic) and it is flexible (fluid).
What does cholesterol do for the cell membrane? It provides the cell membrane with some rigidity. Otherwise the membrane would be too flexible.
What do proteins in the membrane do for the cell? They can act as enzymes, receive signals, and transport items across the cell membrane.
What is passive transport? any form of movement across a membrane that does not require the use of ATP.
What are some examples of passive transport? Diffusion, facilitated diffusion, osmosis.
What is diffusion? Diffusion is when there is movement of a substance from an area of high concentration of that substance to an area of lower concentration.
What is osmosis? Osmosis is the diffusion of water across the membrane from high water concentration to low water concentration.
What is a concentration gradient? When there are more molecules of one type on one side of the membrane than the other.
What is a hypertonic solution? A solution where the solute is MORE concentrated than another.
What is a hypotonic solution? A solution where the solute is LESS concentrated than another.
What is an isotonic solution? A solution where the solute is equally concentrated on either side of the membrane.
What is a solute? A solvent? A solute is the item that is being dissolved. A solvent is the liquid doing the dissolving.
What happens to a cell in a hypertonic solution? Why? The cell will shrink because water is moving out to balance the solution.
What happens to a cell in a hypotonic solution? Why? The cell will expand and perhaps even burst because water is moving in to balance the solution.
What happens to a cell in an isotonic solution? Why? The cell will stay the same because it is at a state of dynamic equilibrium. Water is moving in and out of the cell at the same rate.
What is active transport? transport of a substance across a cell membrane against the concentration gradient; requires ATP (energy).
What is endocytosis? It is the process by which cells absorb material from outside the cell by engulfing it with their cell membrane.
What is exocytosis? It is the process by which a vesicle fuses with the cell membrane, dumping its contents outside the cell.
What is phagocytosis? It is when cells engulf food with their cell membrane and then digest it.
What is pinocytosis? It is when cells engulf water by forming vesicles.
How does molecule size affect diffusion? The larger the molecule, the less likely it is to cross the membrane. Smaller molecules will diffuse first.
How does concentration affect diffusion? The more concentrated the solution, the faster it will diffuse across the membrane.
Created by: jdesrochers