5.5-5.11 Quiz/Vocab Flashcards
what do membrane proteins do?
specialize
in what ways to membrane proteins specialize?
anchor cells to substrates
transport molecules
catalyze enzymatic reactions
receive information
identification tags
what does it mean for biological membranes to be selectively permeable?
for membranes to allow some but not all substances to pass
what is the membrane permeable to?
small non polar molecules and some small polar molecules; water is small enough to pass through gaps slowly
what is the bilayer impermeable to?
to charged ions and most large polar molecules
are gases such as N2, O2, and CO2 permeable?
yes
are hydrophobic non polar molecules permeable?
yes
are small polar molecules such as H2O, glycerol, and urea permeable?
yes
are large polar molecules such as glucose and uncharged mono & disaccharides permeable?
NO
are ions and electorally charged molecules permeable?
NO
How do impermeable substances cross the membrane?
via transport proteins (carrier and channel)
what are carrier proteins?
proteins that change shape and transfer molecules
What does carrier mediated transport transfer?
solutes
what are the two forms of carrier-mediated transport?
active and passive transport
what do transfer proteins do?
form pores in the membranes that allow passive transport (diffusion) of water and ions
what is diffusion?
the movement of ions and small molecules down a concentration gradient and through the membrane (simples and facilitated)
what is concentration gradient?
when particles in a liquid or gas are unevenly distributed
how does diffusion move across concentrations?
from an area of high concentration to an area of low concentration
what is a membrane gradient?
potential energy capable of doing work
how is the rate of diffusion determined?
by size, shape, and the charge of particles as well as temperature
what is dynamic equilibrium?
occurs due to diffusions where particles are uniformly distributed with no net change to the system
what is simple diffusion?
small, non polar solutes moving directly through the membrane and down the concentration gradient
what is facilitated diffusion?
specific proteins make the membrane permeable to specific ions or polar molecules
what do channel proteins do?
form hydrophilic channels where specific ions move down their electrochemical gradients
what is osmosis?
the net movement of water through a selectively permeable membrane from high concentrations of water to lower concentrations
what is osmotic pressure?
exerted on the side contains the higher solute concentration to prevent the diffusion of water from the other side
what is an isotonic solution?
no net movement of water molecules
what is a hypertonic solution?
high concentration of solutes outside of the cell; cell’s loose water and shrink
what is a hypotonic solution?
lower confute concentration out the cell; cell gains water and swells
what is tonicity?
whether or not a cell is isotonic, hypotonic, or hypertonic ; relative compared to another solutions
when cells shrinks in hypertonic solutions?
crenation (animals), and plasmolysis (plants)
when cells swell in hypotonic solutions?
hemolysis (animals), turgor pressure (plants)
what is active transport?
metabolic energy is used to pump materials from low concentration to high concentration
what is indirect active transport?
a concentration gradient provides energy for the co-transport of another substance
what energy source does a NA-K pump use?
ATP to pump NA+ out of the cell and K+ into the cell
What does ATP produce?
a concentration gradient
what is a cotransport system?
energy produced by moving solute down its concentration gradient is used to transport another solute up its concentration gradient
what does cotransport do?
indirectly provide energy for active transport
what is exocytosis?
vesicles export large molecules by fusing a vesicle with the plasma membrane
how does endocytosis import material?
through phagocytosis, pinocytosis or receptor-mediated endocytosis
what is phagocytosis?
cellular eating; folding of the plasma membrane encloses a cell or food particle, forming a vacuole which can fuse with lysosomes
what is pinocytosis?
drinking; fluid with dissolved materials is drawn in by folds in the plasma membrane
what is receptor mediated endocytosis?
specific molecules combine with receptor proteins in the membrane
what do junctions do?
connect cells that form strong connection, preventing passage of materials, or establishing rapid communication between adjacent cells
what types of junctions are there?
anchoring, tight, gap, and plasmodesmata
what do anchoring junctions do?
connect cells of an epithelial sheet; cadherins are important protein component
what are two types of anchoring junctions?
desmosomes, and adhering junctions
what do tight junctions do?
seal off intercellular spaces between some animal cells, allowing no space to remain between the cells
what do gap junctions do?
allow the transfer of small molecules and ions, communication; can open and close, connexion molecules group to for cylinders
what does plasmodesmata do?
allow for movement between the cells
