plasma membrane & organelles Flashcards
plasma membrane structure
semi-permeable barrier allowing passage of oxygen, nutrients, waste
phospholipid bilaterally (2 layers of phospholipid)
saturated plasma membrane
saturated hydrocarbon tails packed tightly together (viscous)
can occur in low temps
unsaturated plasma membrane
hydrocarbon tails prevent tight packing, more fluidity
can occur in high temps
cholesterol in plasma membrane
stabilises membrane fluidity
role of membrane protein:
signal transduction
relay messages from external environment/body into cell
eg. growing, dividing, moving, making something, dying
role of membrane protein:
cell recognition
often involving glycoprotein = membrane protein w added sugars
role of membrane protein:
intercellular joining
some proteins form long-lasting connections between cells
role of membrane protein:
linking cytoskeleton & extracellular matrix
allows cell to physically connect w protein structures outside the cell (extracellular matrix)
role of membrane protein:
membrane transport
allows small amounts of particular moles to move across the membrane, either passive or active
passive transport
easiest form via diffusion
no energy required as moved down their concentration gradient
membrane is permeable to lipid soluble (hydrophobic) molecules
movement of hydrophilic molecules requires…
membrane proteins - channels & carriers aiding movement of specific substances down their concentration gradient
membrane protein - channels
open/close in response to signals
membrane protein - carriers
undergo shape change to help guide molecule into cell
active transport
requires energy
& transport proteins - carriers that use energy (ATP) to move specific substances against their conc gradient
co-transport
indirect active transport requiring ATP
when one substance is pumped across membrane, its conc gradient is used to power the movement of a second substance against its conc gradient
