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83 Cards in this Set
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- Back
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selective permeability
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the allowance of some substances to cross a membrane more easily than others; fundamental to life
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lipids and proteins
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What are the staple ingredients of membranes?
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phospholipid
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most abundant type of lipid in membranes
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amphipathic
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to have a hydrophilic region and a hydrophobic region; pertains to most membranes
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fluid mosaic model
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idea that membrane is fluid structure with "mosaic" of various proteins embedded in or attached to a double layer of phospholipids
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okay
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[just say okay] scientists make models as hypotheses to organize and explain existing information
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Gorter and Grendel
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two Dutch scientists who reasoned that cell membranes were phospholipid bilayers, used as stable boundary between two aqueous solutions
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Davson and Danielli
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1935: two scientists that suggest membranes have two sides of hydrophilic regions; propose sandwich model: phospholipid bilayer between two layers of proteins
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electron microscope
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type of microscope that was used to study membranes
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problem
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[just say problem] 1st problem with Davson and Danielli's sandwich model: generalization that all membranes are identical
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7-8
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how many nm's is the plasma membrane thick?
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problem
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[just say problem] 2nd problem with Davson and Danielli sandwich model: protein placement; proteins are amphipathic so they cannot be completely in one certain region, it is problematic with the opposite region
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Singer and Nicolson
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two scientists who in 1972 proposed that membrane proteins are dispersed, individually inserted into the phospholipid bilayer with their hydrophilic regions protruding
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freeze-fracture
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method of preparing cells by freezing them and then splitting the membrane along the middle of the bilayer, (pull apart chunky sandwich);
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okay
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[just say okay] models make inspiration for further investigation, and can be changed as knowledge advances
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hydrophobic interactions
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what primarily holds together membranes?
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laterally
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which way can lipids and some proteins shift in their phospholipid layer?
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Frye and Edidin
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two scientists who showed that membrane proteins shift; some move driven by cytoskeletal fibers by motor proteins, but some are also immobile by attachment to cytoskeleton
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okay
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[just say okay] the solidifying point of a membrane varies, depending on the type of lipids it is comprised of
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unsaturated hydrocarbons
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what type of a part of lipid will keep a membrane fluid by being unable to pack closely together?
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cholesterol
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steroid that is wedged between phospholipid molecules in animal cells; "temperature buffer"
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37
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at what degrees Celsius does cholesterol make the membrane less fluid by restraining phospholipid movement?
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cholesterol
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what lowers the temperature of a membrane solidifying by wedging itself between phospholipid molecules, making it impossible for them to pack closely together?
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okay
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[just say okay] when a membrane is solid the permeability changes { enzymes can deactivate, lipid composition can change, etc.}
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proteins
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what macromolecule determines the function of the membrane?
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integral protein
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protein that penetrates the hydrophobic core of the lipid bilayer
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transmembrane protein
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protein that spans the membrane, goes through the whole thing
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okay
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[just say okay] hydrophobic regions of an integral protein consist of 1+ amino acids, coiled in helices
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okay
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[just say okay] some proteins have a hydrophilic passage through it to allow hydrophilic materials in the cell
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peripheral protein
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protein that is not embedded in the lipid bilayer; appendage that is loosely bound to the surface of the membrane, often exposed to parts of integral protein
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cytoskeleton
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what sometimes keeps some membrane proteins in place on the cytoplasmic side?
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extracellular matrix
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what sometimes keeps some membrane proteins in place on the extracellular side?
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transport
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function of a protein that allow the passage of material; can be by means of a hydrophilic channel or by the shuttling of a substance by changing shape (hydrolyzes ATP)
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enzymatic activity
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function of protein that is essentially to be an enzyme built into protein
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signal transduction
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function of a protein to use binding sites on the extracellular side to change shape and send signals to the interior
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cell-cell recognition
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function of a protein to be an identification tag to be recognized by other cells
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intercellular joining
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function of a protein to hook together cells through junctions (gap, tight, etc.)
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attachment to the cytoskeleton and extracellular matrix
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function of a protein to help coordinate extracellular and intracellular changes; help maintain cell shape and cell location
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cell-cell recognition
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key ability for organism to function { sorting cells into tissues and organs, basis of rejection of foreign cells, important in defense of vertebrates}
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glycolipids
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lipid covalently bonded to a membrane carbohydrate (less than 15 sugars)
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glyoprotein
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protein covalently bonded to a membrane carbohydrate
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carbohydrate
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this macromolecule is key when on the extracellular side of a cell to for identification, because they can vary individual to individual, cell type to cell type, species to species, etc. (used for identification)
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inside
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what part of a vesicle (inside or outside) becomes part of the extracellular side of the cell membrane?
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outside
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what part of a vesicle (inside or outside) becomes part of the cytoplasmic side of the cell membrane?
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supramolecular structure
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of what is the biological membrane a prime example? (allow molecules to have emergent properties that it wouldn't have isolated)
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hydrophobic molecules
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what type of molecules can pass the cell membrane easily? (hydrocarbons, CO2, oxygen, etc.) because they dissolve easily
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hydrophilic molecules
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what type of molecules have a hard time passing the cell membrane (do so very slowly)? (glucose, water, other polar molecules, etc.)
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channel protein
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type of transport protein that has a hydrophilic channel, allowing ions and certain molecules to pass through
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carrier protein
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type of transport protein that changes shape when bound to certain molecules, thus allowing the molecule to shift to the other side of the membrane
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aquaporin
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channel protein that is mainly for water passage; allows 3 billion water molecules to pass in a line per second
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glucose
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what uses a certain carrier protein to go through red blood cell membrane?
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diffusion
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the movement of molecules so they spread evenly in an available space/equilibrium; directional
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concentration gradient
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what any substance will diffuse down; region along which density of chemical substance decreases
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concentration gradient
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what represents potential energy?
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osmosis
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diffusion of water across semipermeable membrane
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tonicity
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ability of a solution to cause a cell to gain or lose water
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isotonic
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same (environment wise)
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hypertonic
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solution that has more non-penetrable solutes outside the cell, causes water to leave
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hypotonic
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solution that has less non-penetrable solutes outside the cell, causes water to enter
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lyse
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the act of a cell bursting from swelling, like an overfilled water balloon
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osmoregulation
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the control of water balance; key for cells that are not in a tolerable solution
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turgid
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very firm; key for plants in a hypotonic solution
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flaccid
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limp; happens to cells with cell walls when immersed in isotonic solution
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plasmolysis
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in a hypertonic solution, the plasma membrane will shrink as water is lost and pull away from the cell wall; causes wilting and lead to death
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facilitated diffusion
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the passing of hydrophilic molecules and some ions through the membrane with the help of transport proteins
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ion channel
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channel protein group that opens and closes in response to a stimulus
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gated channel
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opens and closes in response to stimulus; channel protein type (stimulus can be chemical or electrical)
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cystinuria
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human disease that has the absence of a carrier protein that would transport cysteine and other amino acids across the membranes of kidney cells
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sodium-potassium pump
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active transport system exchanging potassium to go into the cell and sodium to leave the cell
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membrane potential
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voltage across a membrane; (range from -50 to -200)
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electrochemical gradient
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combination of chemical and electrical forces on an ion
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negative
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charge of the plasma membrane? based on unequal distribution of cations and anions
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proton pump
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main electrogenic pump of plants, fungi, and bacteria that actively transports hydrogen ions out of the cell
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cotransport
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using active transport to pass one solute, but also bringing several other solutes
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hypotonic
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organisms in freshwater are in what kind of solution?
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okay
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[just say okay] facilitated diffusion uses carrier proteins too. carrier proteins aren't just for active transport
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cystinuria
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kidney disease based on malfunction of transport system
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Na
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In the Na- K active transport system, which goes out(3)?
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K
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In the Na-K active transport system, which goes in (2)?
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voltage
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what is created by differences in the distribution of positive and negative ions?
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membrane potential
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voltage difference across membrane; maintained by active transport
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chemical force
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part of electrochemical gradient; ion's concentration gradient
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electrical force
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part of electrochemical gradient; effect of the membrane potential on ion's movement
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