_____ tends to diffuse from an area of ____ water concentration to an area of _____ water concentration.
Comparing solutions A __________ solution is a solution in which the concentration of dissolved substances is _________ than the concentration inside the cell. If a cell is placed in a hypertonic solution, osmosis will make the water _____ the cell and the cell will shrink.
A _______ solution is a solution in which the concentration of dissolved substances is _______ than the concentration inside the cell. If a cell is placed in a hypotonic solution, osmosis will cause water to move through the plasma membrane _____ the cell and the cell will burst. Comparing solutions
An ______ solution is a solution in which the concentration of dissolved substances is the _____ as the concentration inside the cell. Psst! Remember “equilibrium”?
Osmotic Pressure Osmosis exerts a pressure known as ________ _________ on the hypertonic side of a selectively permeable membrane.
Because the cell is filled with salts, sugars, proteins, and other molecules, it will almost always be _________ to fresh _______. If so, the osmotic pressure should produce a net _________ of water into the cell. As a result, the volume of the cell will _________ until the cell becomes swollen or bursts. Osmotic Pressure
Osmosis Cells in _______ organisms are not in danger of bursting because they are bathed in fluids, such as blood, that are _______. Other cells are surrounded by tough cell walls that prevent the cells from expanding even under tremendous osmotic pressure.
Facilitated Diffusion _____ ________ have protein channels that act as carriers, making it easy for _______ molecules to cross.
Facilitated Diffusion The movement of specific molecules across cell membranes through protein channels is known as _______ _______. Hundreds of different protein channels have been found that allow particular __________ to cross different membranes.
Facilitated Diffusion Protein channel Glucose molecules
Facilitated Diffusion Although _________ diffusion is fast and specific, it is still diffusion. Therefore, facilitated diffusion will only occur if there is a ______ concentration of the particular molecules on one side of a cell membrane as compared to the other side.
Active Transport Sometimes ______ move materials in the ________ direction from which the materials would normally move—that is against a concentration difference. This process is known as ______ _______. Active transport requires energy.
Active Transport Molecular Transport * In active transport, _____ molecules and ions are carried across membranes by proteins in the membrane. * Energy use in these systems enables cells to _________ substances in a particular _______, even when diffusion might move them in the opposite direction.
Active Transport Molecule to be carried This transports particles _______ a concentration difference. This forced movement requires energy.
Active Transport Endocytosis and Exocytosis – ______ molecules and even ______ clumps of material may undergo active transport through the ____ ________. – ____________ is the process of taking material into the cell by means of infoldings, or pockets of the cell membrane. – The pocket breaks loose from the outer portion of the cell membrane and forms a _______ within the cytoplasm.
Two examples of endocytosis are phagocytosis and pinocytosis. In __________, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it. Phagocytosis requires a considerable amount of ______.
In _________, tiny pockets form along the cell membrane, fill with _______, and pinch off to form vacuoles within the cell. Two examples of endocytosis are phagocytosis and pinocytosis.
Active Transport Exocytosis – Many cells also release ______ amounts of material from the cell, in a process called ________. – During _________, the membrane of the vacuole surrounding the material fuses with the ____ _______, forcing the contents out of the cell.