1.3 - Cell Membranes & Transport Flashcards
what are the components of a plasma membrane?
intracellular and extracellular proteins
glycoproteins
phospholipids
cholesterol
what is the fluid mosaic model ?
a model that describes membrane structure as a ‘sea’ of mobile phospholipids studded with various proteins
what are intrinsic proteins ?
proteins found within the phospholipid bilayer
includes channel and carrier proteins
what are the functions of intrinsic proteins
structural support
carry water-soluble molecules across the phospholipid bilayer
form ion channels to enable active transport
what are extrinsic proteins?
proteins found in the edges of the phospholipid bilayer
what are the functions of extrinsic proteins ?
receptors
act as antigens, enabling cell recognition
help cells adhere to each other
name factors affecting the permeability of the plasma membrane
temperature
pH
organic solvents
how does temp effect PM permeability?
as temp increases - phospholipids have more KE and move more,
This increases the fluidity and permeability of the PM
what happens to PM if temp is too high ?
channel and carrier proteins will denature affecting membrane permeability
cell will eventually break down completely
how do organic solvents affect PM permeability?
they dissolve membranes disrupting cells
this increases the fluidity and permeability of the PM
define diffusion
the passive movement of small non-polar, lipid soluble molecules from and area of high concentration to an area of low concentration
what factors effect the rate of diffusion?
temperature
concentration gradient
diffusion distance
surface area
size of molecule
define osmosis
the passive movement of water molecules form a region of high water potential to a region of lower water potential through a selectively permeable membrane
define facilitated diffusion
the net movement of substance from an area of high conc to an area of lower conc through a transport protein without the use of energy
give an example of facilitated diffusion
Co-transport
