fluid mosaic model Flashcards
what is the cell membrane mostly made up of ?
phospholipids and proteins
what can phospholipids form?
bilayers
with one sheet of phospholipid molecules opposite another
what are the tails?
hydrophobic fatty acid tails
what are the heads?
hydrophillic phosphate head
are phosphate heads hydrophillic or hyfrophobic?
hydrophillic
are fatty acid tails hydrophillic or hydrophobic?
hydrophobic
what does the phospholipid component allow ?
alllow lipid soluble molecules across but not water soluble
which way do the hydrophillic heads point?
outwards`
which way do hydrophobic tails face ?
inwards
what do the hydrophillic heads interact with ?
water in the cyptoplasm for rhe inner layer
the outer layer interacts with water surrounding the cell
what are extrinsic proteins?
they are proteins on either surface of the bilayer
what do extrinsic proteins do ?
they provide structural support and form recognition sites by identifying cells
and receptor sites for hormone attachment
what are intrinsic proteins?
they have hydrophobic and hydrophillic parts
some are channel proteins
span the membrane
what is the function of intrinsic proteins?
some are carriers and trasnport water soluble substances
others allow active transport of ions across by forming channels
is the hydrophillic phosphate head polar ?
yes
it interacts with other polar molecules such as water
protein hormones such as insulin and adrenaline are insoluble in lipids so cant diffuse through the phospholipid membrane of the cell
intead they ?
they bond to extrinsic protein receptor molecules which influences behaviour of cells
why is the membrane structure called fluid mosaic ?
fluid : phospholipids can move within a layer relative to one another
mosaic: proteins embedded vary in size shape and pattern
what are the components of a cell membrane
hydrophillic phosphate head
hydrophobic fatty acid tail
channel, carrier, intrinsic, extrisnic proteins
cholesterol
glycolipid
glycoprotein
where is cholesterol found in the membrane ?
between phospholipid molecules
in the hydrophobic layer
what does cholesterol do to membrane?
makes it more rigid and stable
where are glycoproteins and glycolipids found?
on the outer layer of the membrane
what is the glycocalyx?
the carbohydrate layer around the membrane
some molecules in the glycocalyx have roles as hormone receptors
or in cell to cell recognition
what does the membrane being selectively permeable mean?
they are permeable to water molecules and some other small molecules
but not to large molecules
barrier to some molecules but lets others cross
what is it called when proteins are bonded to lipid molecules on the membrane?
lypoproteins
what is it called when proteins are bonded to carbohydrate groups on the membrane?
glycoproteins
Short chain carbohydrates attached to proteins are called?
glycoproteins.
Short chain carbohydrates attached to phospholipids are called?
glycolipids
what happens if there is not enough cholesterol in the membrane?
membrane becomes too fluid
what happens if there is too much cholesterol in the membrane?
membrane becomes too rigid
what is the role of channel proteins?
allows the passage of polar molecules by facilitated diffusion
