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Name _____________________________ Bio PreAP/GT 3.3 Cell Membrane (p. 81) Cell Membranes are composed of two phospholipid layers. The cell membrane, or the _____________ membrane, forms a boundary between a cell and the outside environment and controls the passage of materials into and out of the cell. • A phospholipid molecule has three parts: o Head composed of ____________ __________ and _____________ Charged [polar] ________________ - forms _______________ bonds with water o 2 ____________ ___________ tails Nonpolar ________________ – attracted to each other and repelled by water o Arranged as a ______________ polar _________________ on the outside nonpolar ______________ in the middle • Sketch figure 3.1 in the space provided. Label, proteins, protein channel, phospholipid, cholesterol and carbohydrate chain • • • Embedded in the plasma membrane are cell surface ____________ that allow larger materials to pass into and out of the cell. o These proteins are called _____________. ________ _________ _______ describes arrangement of molecules in membrane. o Flexible; not rigid o Membrane behaves as a fluid ______________ ________________ - membrane allows some, but not all, materials to cross. Chemical signals are transmitted across the cell membrane. • _____________ – protein that detects a signal molecule and performs an action in response. o Recognizes and binds to only certain molecules – ligand. o Causes them to change shape. • _____________ receptor – within the cell • _____________ receptor –located in the cell membrane 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. • ________________ transport – movement of molecules across a cell membrane _________________ energy input from the cell o _____________________ - movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration. It take place wherever there is a difference in __________________ within the solution. __________________ _______________ - difference in concentration Particles of a solute and solvent are constantly moving from areas of _______ concentration to areas of ___________ concentration. These particles continue to move until the concentrations are equal or reach . . . ______________________. o ____________________ - diffusion of water molecules from high to low across a semipermeable membrane If a solution has a higher concentration of dissolved particles, then it will have a _________concentration of water molecules in the same solution the increased pressure that results from an increase of water is called ______________ ___________________ Refer to the figures below to answer the following questions. 1. 2. 3. 4. 5. 6. concentration of sucrose is higher in compartment ? concentration of water is higher in compartment ? osmosis occurs with movement from _?_ into _?_ diffusion of sucrose will/will not occur. level of column A will increase/ decrease/ remain the same. level of column B will increase/ decrease/ remain the same. *A column of fluid develops which creates a pressure that prevents the solution from increasing its volume further. Osmotic pressure has the effect of pushing water molecules of compartment A back into B. At this point, the number of water molecules moving in and out of compartment A is equal, so _______________________ exists. A. The cell solution is said to be ____________________ when there is a ______________ concentration of solute in the environment than that in the cell. Thus, the environment solution is said to be ____________. Water will move _______________ the cell. This is the shrinking of the cell due to water leaving the cell. . . _______________________________. B. The cell solution is said to be ____________________ when there is a _______________ concentration of solute in the environment than that in the cell. Thus, the environment solution is said to be _____________. Water will move ___________ the cell. This is the bursting of the cell due to water entering the cell. . . ______________________________. C. A cell is said to be _________________ when the concentration of solutes in the environment and in the cell are the _________________. Equal amounts of water will move _____________ and _________________ the cell. o Do you understand Osmosis? Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to cell) hypertonic or hypotonic Which way does the water flow? in or out of cell o ________________ _________________ - diffusion of molecules across a membrane through transport proteins. Examples: Flasks X, Y, and Z contain solutions with different concentrations of the solute NaCl. Flask X has 0.5% NaCl, Y has 0.9% NaCl, and Z has 1.5% NaCl. Red blood cells (0.9% NaCl) will be placed in each flask. Flask X _____% of NaCl in flask _____% of water in flask _____% of NaCl in red blood cells _____% of water in red blood cells The environment solution is _______ and the cell solution is __________ , therefore water will move ______ the cell. Flask Y _____% of NaCl in flask _____% of water in flask _____% of NaCl in red blood cells _____% of water in red blood cells The environment solution is _______ and the cell solution is __________ , therefore water will move ________ the cell. Flask Z _____% of NaCl in flask _____% of water in flask _____% of NaCl in red blood cells _____% of water in red blood cells The environment solution is _______ and the cell solution is __________ , therefore water will move _____ the cell. 3.5 Active Transport, Endocytosis, and Exocytosis Proteins can transport materials against a concentration gradient. • • • Cells must have a way to maintain concentrations of important food molecules at a level different from the concentration level outside the cell. Active transport uses __________ to transport particles through a membrane _________ the concentration gradient. An example of an active transport channel is the _____________-______________ pump. ____________ is required. o ___________________ is the taking in of particles into a cell by engulfing them in a membrane. o Two types: _________________________ is the taking in of liquid or dissolved materials. _________________________ is the taking in of large solid materials. o ____________________ is the removal of wastes out of a cell by the fusion of a vesicle with the membrane