chapter 7 Flashcards
membrane
does facilitated diffusion require energy
no
what molecules aid in facilitated diffusion
carrier or channel proteins
aquaporin
it is a hydrophilic channel in the protein that helps molecules get through by osmosis
how do carrier proteins bring molecules into the cell
carrier protein changes shape to transport solutes (glucose to pancreas membrane)
what is active transport
when a molecule goes against a concentrated gradient (low conc to high conc)
what does active transport require that passive doesn’t
active:
requires energy (ATP)
must be a carrier protein
allows cells to maintain different concentration levels
what is the sodium potassium pump
pumps 3 Na cations out of the cell and 2 K cations into the cell. Requires energy
binding of K+ triggers what?
release of phosphate
what is the role of a phosphate group in the S-P pump?
it allows the protein changes and releases Na+ out of the cell and removing the phosphate and returning to the original shape
the binding of Na+ stimulates what?
ATP hydrolysis
what side determines the charge of the cell membrane
cytoplasm side
what can cause the membrane to be potentially negative?
unequal distribution of ions across the membrane, more negative ions on the inside of the cell
movement of ions across the membrane is dependent on what two forces?
chemical force and electrical force
what is chemical force?
ions concentration gradient
what is electrical force?
effect of membrane potential on the ions movement
what is electrochemical gradient?
combined forces of chemical and electrical
net negative charge inside a cell and net chemical gradient favors what?
movement of Na+ into the cell
what is proton pump?
continually pushing protons against gradient from inside of the cell to the outside
the proton pump is used by which organisms?
plants, fungi, and bacteria
the sodium potassium pump is used by which organisms?
animals
is the proton pump active or passive transport?
active bc it requires energy
where does the proton pump get its energy for its transport
the ATP potential energy is stored in membranes to be used when need be
what is cotransport
the additional energy from the proton pump pushes the H+ and sucrose into the cell.
how is ATP involved in cotransport
ATP is indirectly providing the energy necessary for cotransport (sucrose)
exocytosis
large molecules exited by fusion of molecules to the plasma membrane
endocytosis
the cell takes in new biological molecules and forming new vesicles from the plasma membrane
phagocytosis
cell engulfs a particle of food or bacteria via pseudopodium to form a food vacuole
pinocytosis
cell gulps droplets of extracellular fluid into tiny vesicles
how is food digested
lysosome
receptor mediated endocytosis
enables cells to acquire bulk quantities of specific substances
ligand
molecule that binds specifically to a receptor site of another molecule
familial hypercholesterolemia
inherited disease characterized by very high cholesterol levels in the blood
tonicity
the ability of a solution surrounding a cell to cause that cell to gain or lose water
free water
crosses selectively permeable membrane
bound water
attached to hydrophilic parts of the solute molecules (sphere of hydration)-doesn’t cross membrane
osmosis
movement of water molecules across a selectively permeable membrane
does osmosis require energy
no
how does water move in a solute concentration
water moves from an area of lower to higher solute concentration
equilibrium
solute molecules continue to cross membrane but at a similar rate in both directions
Does diffusion require energy
no
what is diffusion
the movement of a substances down its concentration gradient by random thermal
what is passive transport
is one mechanism that moves molecules across cells
what is considered “the edge of life”
plasma membrane
what is selective permeability
allows some substances to cross more easily than other substances
are organelles selective permeable?
yes
fluid-mosaic model
currently the most accurate model to explain the structure of the plasma membrane
how does the membrane represent “fluidity”
composed of a fluid phospholipid bilayer
what allows cells to maintain unique internal environments
selective permeability of a plasma membrane
how does the membrane represent “mosaic”
proteins are embedded or attached to the phospholipid bilayer
what is the dynamically structured mosaic model
current model that emphasizes on mosaicism rather than fluidity. Membranes are more packed with proteins than originally thought
how are membranes held together
WEAK hydrophobic interactions
why does the plasma membrane need to be flexible
for things to be able to get through
why can some proteins move across the plasma membrane
some proteins can’t move because they are rigidly attached to the cytoskeleton and some aren’t so they are more free
what are the differences in saturated and unsaturated membranes
at low temps,
saturated hydrocarbons solidify
unsaturated hydrocarbons stay fluid
what prevents hydrocarbons from solidifying
double bonds
what is cholesterol’s involvement in membranes
at low temps: keeps fluidity
at high temps: less fluid
why is fluidity important for membranes
need to be fluid for molecules to get through, but not too fluid to lose shape
how do enzymes move through membranes
they move laterally
which types of proteins reach both outsides of the membrane
both, integral and peripheral proteins
integral proteins
cross the plasma membrane (hydrophobic/philic regions)
peripheral proteins
attached to the inner surface of the membrane some times via integral proteins
how is the plasma membrane supported
attachments to cytoskeleton (microfilaments) on cytoplasmic side
what does the plasma membrane attach to on the extracellular side, via the protein
collagen fibers and proteoglycans (which are attached to fibronectin)
what are the 6 major functions of the membrane proteins
transport enzyme activity signaling transduction cell to cell recognition intercellular joining attachment to cytoskeleton and ECM
membrane carbohydrates
usually short-branched polysaccharides (15
glycolipids
lipids with carbohydrates covalently attached
glycoproteins
proteins with carbohydrates covalently attached
where are glycoproteins and glycolipids found
within membranes
How does a transmembrane glycoprotein become embedded within plasma membrane
components of these membranes are synthesized within the ER
Where are phospholipids and glycoproteins modified
Golgi
what molecules move easily through the plasma membrane and why
molecules are non-polar and hydrophobic. They don’t need aid of membrane proteins
what molecules move difficultly through the plasma membrane and why
polar molecules because it is troubled in the hydrophobic environment
