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83 Cards in this Set

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