Term
| The plasma membrane exhibits selective permeabilty , what does that mean ?Why is it important? |
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Definition
| The plasma membrane allows some subtances to cross it more easily than others. The ability of the cell to discriminate in its chemical exchanges with its environment is fundamental to life |
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Term
| what are the staple ingridients of membranes? |
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Definition
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Term
| what are the most abundant lipids in most membranes? |
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Definition
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Term
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Definition
| it is an amphipathic molecule , meaning it has both a hydrophlic region and a hydrophobic region |
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Term
| How are phosolipids and protiens arranged in the membranes of cells |
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Definition
| in the fluid mosaic model , the membrane is a fluid structure of various protiens embedded in or attached to a double layer of phospholipids |
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Term
| why arent membrane protiens not very soluble in water |
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Definition
| because they are amphipathic |
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Term
| what is the primary function that holds membranes together |
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Definition
| hydrophobic interactions , which are much weaker than covalent bonds. |
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Term
| the temperature of which a membrane solidifies depends on what ? |
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Definition
| the types of lipids it is made of |
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Term
| what determines most of the membranes functions |
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Definition
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Term
| what are the two major populations of membrane protiens |
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Definition
intergral protiens- penetrate they hydrophobic interior of the lipd bilayer
peripheral protiens- are not embedded in the lipid bilayer , they are appendages loosely bound to the surface of the membrane |
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Term
| 6 major functions of performed by plasma membrane protiens. |
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Definition
transport - providing a hydrophilic channel across the membrane that is selective
enzymatic activity- a protien built into the membrane may have its active site exposed
signal transduction- has a binding site that fits the shape of a chemical messenger
cell-cell reduction- some glycoprotiens serve serve as identification tags that are recognized by protiens from other cells
intercelluar joining- protiens of adjacent cells hook together in variouskinds ofjunctions
attachment to the cytsoskeleton and the extracellurla matrix |
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Term
| why is cell-cell regonition imporant |
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Definition
| it is crucial to the functioning of an organism , it is also the basis for rejection of foreign cells by the immune system. And an important line of defense in vetebrate animals |
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Term
| how are glycolipds formed |
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Definition
| carbs are covanlently bonded to lipds |
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Term
| how to transport protiens function (channel protiens) |
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Definition
| by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane |
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Term
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Definition
| the movement of molecules of any substance so that they spread out evenly into the available space. A subtance withh diffuse from where tit is more concentrated to where it is less concentrated |
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Term
| what is a concentration gradient |
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Definition
| the region along which the density of a chemical substance increased or decreases |
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Term
| is diffusion spontaneous ? |
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Definition
| yes , no need for input energy for diffusion to take place. |
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Term
| the diffusion of a substance across a biological membrane is called what ? |
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Definition
| passive transport because the cell does not have to expend energy to make it happen |
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Term
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Definition
| the diffusion of free water across a selectively permeable membrane , whether artificial or cellular |
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Term
| the ablilty of a surrounding solution to cause a cell to gain or lose water is called what |
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Definition
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Term
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Definition
| the control of solute concentrations and water balance. |
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Term
| molecules diffuse passively with the help of transport membranes that scan the membrane |
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Definition
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Term
| channel protiens that transport ions are called what? |
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Definition
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Term
| is facilitated diffusion considered passive transport ? why or why not |
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Definition
| yes because the solute is moving down its concentration gradient , which requires no energy |
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Term
| what is the plasma membrane |
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Definition
| barrier that encloses cellular organells |
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Term
| what does active transport enable a cell to do ? |
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Definition
| to maintaint internal concentrations of small solutes that differ from concentrations in its environment |
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Term
| what is the function of a sodium-potassium pump? |
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Definition
| it exchanges Na+ for K+ across the plasma membrane of animal cells. |
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Term
| a transport protien that generates voltage across a membrane is called a what ? |
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Definition
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Term
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Definition
| actively transports protons out of the cell |
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Term
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Definition
| when a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane |
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Term
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Definition
| the cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane |
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Term
this thing decreases membrance fluidity by restraining lipid movement
Prevents tight packing, what is this ? |
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Definition
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Term
| what type of molecules can cross the plasma membrane |
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Definition
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Term
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Definition
solute conc. inside and outside of the cell are equal
No net movement of water. |
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Term
| what does hypertonic mean |
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Definition
solution concentration is lower inside the cell relative to outside
Water rushes out of cell cell. |
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Term
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Definition
Hypotonic-solute concentration is higher inside the cell relative to outside
Water rushes in to cell. |
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Term
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Definition
diffusion aided by proteins.
Occurs down the concentration gradient
Greatly speeds up diffusion of specific substances across the membrane. |
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Term
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Definition
| is the voltage difference across a membrane |
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Term
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Definition
| the coupling of active transport of one substance with the diffusion of another against its concentration gradient |
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Term
-export of substances outside of cell
Transport vesicles (formed from golgi) migrate to membrane, fuse with it, and release their contents |
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Definition
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Term
| what is endocytosis ? what are the three types |
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Definition
is the uptake of macromolecules into cell by forming vesicles from the plasma membrane
Reversal of exocytosis, involving different proteins
Three types of endocytosis
Phagocytosis (cellular eating)
Pinocytosis (cellular drinking)
Receptor-mediated endocytosis |
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Term
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Definition
| A ligand is any molecule that binds to a receptor site of another molecule |
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