Both models show that the plasma membrane has a phospholipid bilayer with
attached proteins .
The Davson-Danielli model shows the plasma membrane as
having two layers
of protein that envelops the the PLs like the bread of of a Sandwich.
However this model is incorrect and Nicholson-Singer's Model shows that in fact
the proteins with proteins permeating PL
are in between the PL
bilayer ,
some the bilayer
completely and some protein only being in one layer (peripheral/integral
Cells have many Membranes Membranes allow cellular com -
partments to have different con-
S
plasma nembrane ditions
↓onoplast (vacuole Membranel
S inner Mitochondrial membrane
6 contains digestive
enzymes
outer chloroplast membrane lysosome
embrane acts as
a barrier
Cytosol
nuclear envelope
membranes are mainly made
of Phospholipids
7
phosphate group
· hydrophylic
Phosphoester Bond, head like water
7
glycero
ester bond hydrophobic
· don't like water
tail
fatty accid D
Explain why phospholipids form a bilayer in plasma membranes use the words :
-
polar
CytoplasmI
hydrophillic head
-
i
Il
hydrophobic tail
-
phosphate group
-
Phospholipid bilayer
-
fatty acid
water, water
-
inside , don't like
away from the aqueous
fatty acid tail -
hydrophobic solution
-
aqueous Solution-salt water
phosphate-Glycerol head-hydrophilic
outside , polar, like water,
near the aqueous solution
and the cytosol inside the
cytoplasm