11M01_ZAO2177_01_SE_CH01.QXD 3/4/11 1:36 AM Page 1 E X E R C I S E 1 Cell Transport Mechanisms and Permeability P R E - L A B Q U I Z 1. Circle the correct term. A passive process‚ diffusion / osmosis is the movement of solute molecules from an area of greater concentration to an area of lesser concentration. 2. A solution surrounding a cell is hypertonic if: a. it contains fewer nonpenetrating solute particles than the interior of the cell. b. it contains
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Cells must move materials through membranes and throughout cytoplasm in order to maintain homoeostasis. The movement is regulated because cellular membranes‚ including the plasma and organelle membranes‚ are selectively permeable[1]. The purpose of an automatic flow of molecules is to create equilibrium on each side of the membrane. In order for molecules to pass through the membranes‚ there must be pores. The size of the pore determines what molecules can cross. Due to the size and polarity‚ only
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in and out of the cell. The movement of substances in and out of a cell through the cell membrane is termed as transport across the membrane. Although the thickness of the cell membrane is only 5-10nm‚ it is a physical barrier to the movement of ions and molecules. The cell membrane and other membranes within a cell are all living membranes that exhibit selective permeability. A selectively permeable membrane enables molecules of certain substances to move across it freely while excluding others
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the diffusion of the movement of water from a region of higher concentration to a region of lower concentration through a cell membrane or other semi-permeable membrane until an equilibrium is reached. It is a special case of diffusion (passive transport). Basic Explanation : Osmosis can occur when there is a partially permeable membrane‚ such as a cell membrane. When a cell is submerged in water‚ the water molecules pass through the cell membrane from
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the visking tubing to make both solution balanced (isotonic). In order for osmosis to occur naturally‚ a semi-permeable membrane is required as a medium. A visking tubing is a semi-permeable membrane‚ therefore it will be used to act as the ‘cell’ for the experiment. This is because the phospholipid bilayer of the cell membrane of an actual cell is selectively permeable‚ allowing diffusion‚ osmosis and active transport to occur. The content of the visking tubing (the sucrose solution) will be acting
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multicellular organisms. { multi = many} Plasma membrane is the outer most covering of the cell that separates the contents of the cell from its external environment. It allows the entry or exit of some materials in and out of the cell. It also prevents the entry of unwanted materials. Plasma membrane is also known as selectively permeable membrane. Substances like CO2 or O2 can move across the cell membrane by a process of diffusion. The spontaneous movement of a substance from higher
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solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane. INTRODUCTION A major determinant of diffusion in a biological system is membrane permeability. Small‚ uncharged molecules pass through cellular membranes easily‚ while most and/or charged molecules
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Osmosis is the diffusion of water molecules from an area of high concentration of sucrose solution to an area of lower concentration of sucrose solution‚ through a selectively permeable membrane. The water molecules move down a concentration gradient in osmosis. Two diagrams of osmosis are shown in figures 1 and 2. Figure 1 shows the diffusion of water molecules through a selectively permeable membrane from an area of highly concentrated sucrose solution to an area of lower concentrated sucrose solution
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thermal motion _D___ the movement of molecules across a membrane that requires the expenditure of cellular energy (ATP) _C___ the transport of water across a semipermeable membrane _F___ term used to describe two solutions that have the same concentration of solutes relative to one another __B__ the movement of molecules across a selectively permeable membrane with the aid of specialized transport proteins a. diffusion b. facilitated diffusion c. osmosis d. active transport e. hypotonic f. isotonic
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from an area of high concentration to an area of low concentration across a semi permeable membrane. An osmotic system is established when a semi-permeable membrane is placed between two solutions. In this biological systems context‚ osmosis is the exchange of water between the potato cell and the surrounding medium of varying sucrose concentrated solutions‚ with the plasma membrane being the semi- permeable membrane. Because water molecules have kinetic energy‚ they are constantly moving around in
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