| Term | Definition |
|---|
| exchange materials | The cells in your body need to ___ ___ with their immediate environment |
| passively, actively | Molecules can pass through membranes ___ or ___ (with or without energy required) |
| thermal motion | Molecules of any substance (solid, liquid or gas) are in a continuous state of movement or vibration, called ___ __. |
| mass | The avg speed of "thermal motion" also depends upon the ___ of the molecule (water moves faster than glucose) |
| faster | The warmer a substance is the ___ its molecules move. |
| collisions | In solutions, rapidly moving molecules cannot travel very far before colliding with other molecules (millions of ___ every second) |
| changes | Each collision ____ the direction of the molecule's movement. |
| diffusion, passive | The movement of molecules from one location to another as a result of their own thermal motion is know as ___. It is also what kind of "mechanism"...passive or active? |
| higher, lower | Constant random motion of molecules = areas of ____ concentrations to regions of ____ concentrations until a uniform concentration. |
| flux | The amount of material crossing a surface in a unit of time is called ___. |
| concentration | The one-way flux of glucose from compartment 1 to compartment 2 depends on the ___ of glucose in comparment 1. |
| move back | After a short time, glucose molecules that have entered compartment 2 will randomly ___ ___ into compartment 1. |
| net flux | What accounts for solute movements in both directions? __ __ |
| difference, one way | Net flux in diffusion is the ____ between the two ___-___ fluxes. |
| diffusion equilibrium | When the difference between the two one-way fluxes is zero (net-flux is zero) the system has now reacheed ____ ____. |
| gradient | The greater the difference between the two one-way fluxes the greater the concentration ____. |
| do not | Most polar molecules ___ ___ diffuse into cells, or very slowly. |
| non polar | ____-____ molecules diffuse very well across membranes. |
| polar | Ions (Na+, K+, Cl-) diffuse across plasma membranes very fast even though they are very ___ |
| integral protein | Ions pass through the cell membrane through the ___ ___ (tunnel's) that are in the membrane |
| channels | Proteins form _____ for the ions to flow through. |
| organic | The small size of the channels allows for some ions to come through but not larger, ____ molecules to pass. |
| size, charged | Ion channels are selective to the ion they allow in because of their ____ selectivity and the __ surface that can either attract or repel ions. |
| membrane potential | The opposite charges on each side of the membrane is called ____ ____ |
| positive, negative | Even if there is no concentration difference of ions there is still a net movement of ____ ions into and ____ ions out of the cell |
| concentration, membrane potential | The two driving forces of ion movement (____ and ____ ____) are known as electrochemical gradient. |
| electrochemical gradient | The two diriving forces of ion movement (concentration and membrane potential) are known as ____. |
| down-hill | The net flux always proceeds from regions of higher concentration to regions of lower concentration. This is known as __ __ diffusion |
| mass, medium, surface, temperature | The magnitude of the net flux depends on several additional factors, regardless of concentration difference: name the four |
| higher, greater | Diffusion factor: the ___ the temperature, the greater the speed of the molecular movement and the ___ the net flux. |
| mass, smaller | Diffusion factor: ____ of the molecule - larger molecules (i.e. proteins) have a greater mass and lower speed = ____ net flux |
| faster, greater | Diffusion factor: mass of the molecule - smaller molecules (i.e. glucose) have a smaller mass and ____ speed = ____ net flux. |
| greater | The greater the surface area between two regions, the greater the space availabe for diffusion = ____ the net flux |
| medium | Diffusion factor: the ____ through which the molecules are moving (gas -vs- a liquid -vs- a solid) |
| faster | The medium through which the molecules are moving ---- molecues diffuse ____ in air than in water because collisions are less in a gas. |
| hydrophobic | The major factor limiting diffusion across a membrane is the ____ interior of its lipid bilayer. |
| transporter | Facilitated diffusion uses a ___ to move solute "downhill" from a higher to a lower concentration across a membrane. |
| active transport | ____ ____ uses a transporter coupled to an energy source to move solute "uphill" across a membrane - against its electrochemical gradient. |
| transporter | With facilitated diffusion the transported solute binds to a specific site on a _____ protein. |
| facilitated | ____ diffusion uses a transporter to move solute "downhill" from a higher to a lower concentration across a membrane. |
| conformational | Facilitated diffusion: protein undergoes _____ change then exposes binding site to the other side of the membrane. |
| ions, molecules | Faciliated diffusion has a limit as to how many ____ and ____ can pass because the transporter must change its shape for each. |
| transporters | Integral membrane proteins are known as ____. |
| conformation | Ion channels can move several thousand times more ions than transporters because there is no change in ____ (shape) |
| facilitated, active | Two types of mediated-transport exist: ____ diffusion and ____ transport |
| concentration | In both simple and facilitated diffusion, solutes move in the direction predicted by the ____ gradient. (downhill) |
| energy | Active transport uses ____ to move a substance uphill (low to high) across a membrane ---- that is, against the substance's electrochemical gradient. |
| saturated, transporters, conformational | Three factors determine the magnitude of solute flux through a membrane with mediated-transport: 1) How __ the binding sites are. 2) number of __. 3) rate at which the __ changes occur in the transport protein |
| against | Active transport moves a substance ____ the substance's electrochemical gradient. (low to high) |
| transporter | Active transport: Requires binding of a substance to the ____ in the membrane ("pumps") |
| pumps | Active transport: Because these transporters move the substance uphill, they are often referred to as ____ |
| energy | Moving substances "up-hill", and keeping things that way, requires constant input of ____ into active transport process. |
| higher, lower | Active transport: must be coupled with simultaneous flow of some energy source from a ____ energy level to a ____ energy level. |
| primary active, secondary active | The two means of coupling an energy flow to transporters are: ___ __ transport and ___ __ transports. |
| primary | Transporter (ATPase) catalyzes the breakdown of ATP ---> phosphorylating itself. This is what kind of active transport? |
| secondary | Transport protein couples the flow of one substance to that of another. This is known as ____ active transport. |
| passively | Secondary active transport: one substance moves ____ down its electrochemical gradient, releasing energy that is then used by hitch-hiker |
| electrochemical | Secondary active transport: The released energy is then used to drive movement of other substance (hitch-hiker) up its ____ gradient |
| low, high | Secondary active transport: hitching a ride while moving ___ to ___ (up it's electrochemical gradient) |
| osmosis | The net diffusion of water across a membrane is called ____. |
| osmolarity | The total solute concentration of a solution is called its ____ |
| aquaporins | A family of membrane proteins known as ____ that form channels through which water can diffuse. |
| polar | Water diffuses across all membranes very rapidly even though it's a ____ (unequal sharing of electrons --> so it has a positive end and a negative end) molecule. |
| semipermeable, compartments | ____ membrane - permeable to water but not to solutes. It creates pressure between __ (inside and outside the cell) |
| osmotic | _____ pressure - the pressure that must be applied to the "solution" to prevent the net flow of water into the solution. |
| isotonic | ____ solution - inside and outside are the same, no change in the cell will occur. |
| hypotonic | _____ (cell expands) - has "less" solute (ex.- from drinking too much water) |
| hypertonic | _____ (cell shrinks) - has "more" solute (like during dehydration) |
| cell membrane | Molecules can enter cells without passing "through" the ____ ____ |
| endocytosis | ___ - Regions of the plasma membrane fold into the cell forming pockets that enclose extracellular fluid, becoming intracellular, membrane-bound vesicles |
| exocytosis | __ - Membrane-bound vesicles in the cytoplasm fuse with the cell membrane and release their contents into the extracellular fluid. |
| energy | Molecules passing through membranes "passively" do not need __ to move (like coasting down a hill in a car) |
| energy | Molecules passing through membranes "actively" need __ to move (like gas in a car to get up a hill) |
| non-polar, non-polar, diffusing | Polar and non-polar things do not mix, like oil & water. Center of the membrane is __-__. So, __-__ molecules have no problem __ across the membrane. |
| affinity, binding, protein, transporter, phosphate, affinity, solute, phosphorylation | Primary active transport - Phosphorylation of the transporter protein changes the __ (attraction) of the transporters solute to the __ site. Once the solute binds to the site it causes a conformation change in the __ (__). Once the transporter has a conformation change, it causes the __ group to be removed --> causing the __ of the binding site to break down --> release of the transported __. The low affinity site returns to it's original side, it is in a conformation that once again permits ___, and the cycle repeats. |
| phosphorylating | Primary active transport - transporter (ATPase) catalyzes the breakdown of ATP --> __ itself. |
| sodium-potassium | One of the most crucial examples of active transport in the body (present in nearly every cell) is the __-__ pump |
| inside, outside | The sodium-potassium pump is responsible for high K+ __ the cell and high Na+ __ the cell. |
| 3,2 | For each ATP that is hydrolized (used), __ Na+ are moved out of the cell and __ K+ are moved in to the cell. |
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