membrane permeability/transport/gradients + some protein synthesis/transport

the four factors in whether a molecule can move through the membrane include

size, polarity, charge, and concentration

one molecule that can move easily through the membrane is

cholesterol

smaller, uncharged molecules

can move through the membrane easily

polar molecules and ions

cannot move through the membrane easily

concentration gradient

difference in the concentration of a substance from one location to another

molecules flow from ___ to ___ concentration gradients

high; low

when moving across a gradient, molecule flow stops when

equilibrium is reached

molecules with high membrane permeability include

gases and very small/uncharged molecules

molecules with moderate membrane permeability include

water and urea

molecules with low membrane permeability include

polar organic molecules

molecules with very low membrane permeability include

charged and polar molecules and macromolecules

___ can pass through membranes but the ___ they produce cannot

gases; ions

a molecule that can sometimes pass through the membrane is

water

the passage of water through the cell membrane is called

osmosis

concentration gradients have both ___ and ___ components

electrical; chemical

true or false: the cell always wants to maintain equilibrium in concentration gradients

false

neurons in muscle cells want ___ for ___

excess potassium ions; signaling

types of cell membrane transport include

simple diffusion, facilitated diffusion, active transport

type(s) of transport where no energy is required

simple and facilitated diffusion

type(s) of transport where energy is required

active transport

simple diffusion

small/nonpolar molecules move independently across membrane, follow gradient, stop @ equilibrium

facilitated diffusion

molecules pass through membrane protein channels, follow gradient, stop @ equilibrium

active transport

cell uses energy to force molecules across the membrane into areas of higher concentration, goes against gradient

for energy, active transport can use

ATP or the energy of another concentration gradient

primary active transport

uses direct energy (ATP), moves a molecule from low to high concentration

secondary active transport

uses the concentration gradient of another molecule instead of ATP

channel protein

membrane protein that allows a certain molecule to pass through, has continuous flow, and can be open or closed

transporter protein

membrane protein that moves certain number of molecules through the membrane at a time, waiting until it's full then dumping its contents into the cell

types of transporter proteins include

uniporter, symporter, antiporter

uniporter

transporter that carries one ion or molecule

symporter/coporter

transporter that carries two ions or molecules at a time in the same direction

antiporter

transporter that carries two ions or molecules in opposite directions; can use energy of one concentration gradient to move the other molecule

once a protein is brought to the ER after its localization signal was recognized, the first part of the protein will be

inserted into the ER

after a protein in the ER is done bring translated, its localization signal will be

removed, which causes the protein to fold into its final shape

main purpose of vesicles

to protect the protein being carried

if a protein is without a vesicle, the cell likely wants

to metabolize them

after gases enter the cell, they become

ions

gases exist inside the cell in this form

dissolved in the cell

glucose ___ pass through the membrane by itself because it is ___

cannot; polar

glucose uses a ___ to pass through the membrane

channel protein; with its concentration gradient

channel proteins are used in this type of transport

facilitated diffusion ONLY

transporter proteins are used in this type of transport

BOTH facilitated diffusion and active transport

transporter proteins can move in

the same or opposite directions

the sodium potassium pump uses ___ and ___ for ___

transporter protein; ATP; active transport

the sodium potassium pump moves Na+ and K+

against their concentration gradients

one reason cells don't want excess sodium ions is

proteins fold around them

one reason to have regulated levels of sodium in cells is

to control osmosis

osmosis

movement of water through a membrane

instead of ___ moving across the membrane, ___ moves across

ions; water

osmosis is very

slow

hypertonic

higher concentration of solute than another solution

hypotonic

lower concentration of solute than another solution

isotonic

when the concentration of two solutions is the same

crenation

shrinkage of cells in hypertonic solution

osmotic lysis

swelling and bursting of cells in hypotonic solution

the body compensates for excess salt or water through

sweating, urination