1.3 cell membranes and transport Flashcards
can solute potential go above zero?
no, it can only go below zero as more solute gets dissolved into it and less water molecules can more around
define active transport?
molecules move against the concentration gradient requiring ATP
define diffusion? (in general)
as a passive process, molecules move randomly - if highly concentrated in an area then there will be net movement away from that area until - equilibrium this is down the concentration gradient.
define endocytosis? and the two types?
large particles enter the cell
phagocytosis (cell eating) and pinocytosis (cell drinking)
define exocytosis?
large particles exit the cell
define facilitated diffusion?
polar molecules must use an intrinsic protein to facilitate transport across the membrane
define osmosis?
the movement of water from an area of high water potential to an area of lower water potential through a semi-permeable membrane and down the concentration gradient.
define simple diffusion in the context of membrane?
diffusion of non-polar molecules across a phospholipid bilayer
define the functions of extrinsic proteins?
structural support and recognising sites by identifying cells
define the functions of intrinsic proteins?
channels/carrier - facilitate diffusion of polar molecules across
pumps - carry out active transport
define the general functions of the cell membrane?
-boundary that separates the living cell from non-living surroundings
-contains extrinsic/intrinsic proteins to diffuse polar molecules across and into the cell
-waste products exit
-secretes enzymes and glycoproteins
define the structure of intrinsic proteins?
span entire membrane (go thru)
describe a carrier proteins structure and how it facilities diffusion?
allows larger polar molecules
molecule attaches to carrier protein at its binding site causing it to change shape and rotate within the membrane releasing it on the other side of the membrane
describe a channel proteins structure and how to facilitates diffusion?
- spans the entire membrane, lined with polar groups that allows polar/hydrophobic molecules to pass through
- they are specific for one type of ion/molecule
- they can close and open (gated channels)
describe a hypertonic solution?
is the surrounding solution of a cell is hypertonic then, there is a higher water potential inside the cell than outside and water moves out of the cell
describe a hypotonic solution?
if the water potential of a solution is hypotonic, it has a higher water potential outside than inside the cell, causing the cell to swell
describe a isotonic solution?
the external solution has the same water potential as the cells contents, with no overall net movement of water.
describe active transport rate against the concentration across membrane? what occurs if there’s a respiratory inhibitor?
increases directly proportionately, until it plateaus as all pumps are active, then falls due to the effect of a respiratory inhibitor
describe co-transport?
type of facilitated diffusion that brings glucose and sodium ions into the cell on the carrier protein, often into the kidney
then sodium leaves through active transport and glucose leaves via facilitated diffusion - MAINTAINS CONC GRAD
describe facilitated diffusion rate against concentration difference across a membrane?
initial increase directly proportionate
until it plateaus as the intrinsic proteins are all in use
unaffected by respiratory inhibitor
describe how temperature affects cell permeability?
membrane is stable until 40ºc
Increased heat energy means increased kinetic energy and the phospholipids move further away from each other and proteins denature - increasing cells permeability
describe simple diffusion rate against the conc difference, will a respiratory inhibitory have any affect?
directly proportionate against each other
no - only active transport
describe the 2 membrane proteins?
extrinsic and intrinsic
describe the fluid-mosaic model?
fluid - phospholipids are fluid and move
mosaic -proteins form random mosaic patterns
