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Biology Exam-Chapter 5
Terms in this set (13)
Be able to describe the fluid mosaic model of cells.
Proteins and substances such as cholesterol become embedded in the bilayer, giving the membrane the look of a mosaic.
The plasma membrane has the consistency of vegetable oil at body temperature, the proteins and other substances are able to move across it.
The molecules that are embedded in the plasma membrane also serve a purpose.
The cholesterol that is stuck in there makes the membrane more stable and prevents it from solidifying when your body temperature is low. (It keeps you from literally freezing when you're "freezing.")
Carbohydrate chains attach to the outer surface of the plasma membrane on each cell. These carbohydrates are specific to every person, and they supply characteristics such as your blood type.
Identify and describe the 4 component groups of the cell membrane (i.e. Table 5.1.)
1. phospholipid bilayer-every cell membrane is composed of a phospholipid bilayer. The other components of the membrane are embedded within the bilayer, which provides a flexible matrix and at the same time a permeable membrane.
2. transmembrane proteins- a collection of protein that float in the bilayer. These proteins include transport and communication across membrane. many integral proteins are not fixed in position.
3. Interior protein network- membranes are structurally supported by intracellular proteins that reinforce the membranes shape. Membranes use networks of other proteins to control the lateral movements of some key membrane proteins, anchoring them to specific sites.
Be able to describe the organization of the phospholipid bilayer.
Identify and describe the different types of proteins associated with the plasma membrane (i.e. role of each in transporting substances across the membrane, receptor, identity markers, attachment to cytoskeleton, cell-to-cell adhesion, etc).
Describe the anatomy of the transmembrane domains of membrane spanning proteins.
-transmembrane segment is any 3-D protein structure wihch is thermodynamically stable in a membrane.
-transmembrane protein is a type of integral membrane protein that spans the entirety of the biological membrane to which it is permanently attached.
Describe movement of substances across the plasma membrane (i.e. diffusion, facilitated diffusion, selective permeability, ion channels, carrier proteins, etc).
Diffusion-moves from high concentration to low concentration
Facilitated diffusion-the process of spontaneous passive transport or molecules or ions across a cell's membrane via specific transmembrane integral protein.
Selective permeability- when a membrane is selectively permeable it selectively lets certain things in and out of the cell.
Ion Channels-pore-forming membrane proteins whos functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume.
Carrier proteins-proteins involved in the net movement of ions, small molecules, or macromolecules
What is osmosis and how does it relate to the membrane.
-osmosis- the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration. Diffusion of water.
-Relates to the membrane because in order for it to occur it needs a selectively permeable membrane to allow these molecules through
What are aquaporins?
Integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane
Describe isotonic, hypotonic, and hypertonic solutios.
-Isotonic=a solution having the same osmotic pressure as some other solution.
-Hypotonic= has a lower concentration of solutes than another solution
-Hypertonic=the total molar concentration of all dissolved solute particles is greater than that of another solution or greater than the concentration in a cell.
Describe active transport.
Active transport uses energy to move materials across a concentration gradient.
Involves highly selective protein carriers within the membrane that bind to the transported substance, which could be an ion or a simple molecule.
Describe the function and purpose of the sodium-potassium pump.
This carrier protein transports sodium Na+ and potassium K+ across the plasma membrane.
For every 3 Na+ transported out of the cell, two K+ are transported into it.
Fueled by ATP hydrolysis.
The affinity is changed by adding or removing phosphate(P), which changed the conformation protein.
Describe the process of coupled transport.
uses ATP indirectly. uses a concentration gradient of one molecule to move another against a gradient in the same direction.
Describe endocytosis (phagocytosis, pinocytosis, receptor mediated) and exocytosis.
Endocytosis- form of active transport in which a cell transports molecules into the cell by engulfing them in an energy-using process.
-Phagocytosis-the intake of solids
-Pinocytosis-the intake of liquid into a cell by the budding of small vesicles from the cell membrane
-Receptor Mediated-process by which cells absorb metabolites, hormones, other proteins and in some cases viruses by the inward budding of plasma membrane vesicles containing protein with receptors specific to the molecules
Exocytosis-a process by which the contents of a cell vacuole are releases to the exterior through fusion of the vacuole membrane with the cell membrane.
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