The Cell Membrane Flashcards
What is a cell membrane?
-The cell membrane is a biological membrane that separates the interior of all cells from the outside environment which protects the cell from its environment.
Functions
-A biological Barrier keeps the stuff inside the cell and separates it from the stuff outside the cell.
-A selective filter that allows certain molecules to pass through it while preventing other molecules from passing through it.
The Cell Membrane’s structure and properties.
- The cell membrane is actually made of Lipids(fat)
- The lipids that make up the cell membrane are found in special molecules called phospholipids.
What are phospholipids made up of?
The name Phospholipid tells you that the molecule is made up of a Phosphate Group(“Phospho”) and a Lipid Group(“lipid”).
Hydrophilic Heads and Hydrophobic Tales
OEach Phospholipid in the cell membrane is made up of one Hydrophilic phosphate head and two Hydrophobic fatty acid tales.
Hydrophilic
“Hydro”=Water
“Philic”=Loving
(Water-Loving)
Hydrophilic
“Hydro”=Water
“Phobic”=Fearing
(water-fearing)
since each phospholipid is made up of a hydrophilic (polar) phosphate head and two Hydrophobic(non-polar) fatty acid tales they have a tendency to form a…..?
bilayer (bi=two.”layers”= layer)
when the fatty acid tales face inwards the phosphate faces____?
outwards
when the phosphate is facing outwards fatty acid tales faces___?
inwards
what does the phospholipid bilayer contains?
phospholipid subunits and proteins that help the cell membrane function
what does cell membrane act more like and why?
liquid more than a solid because the cell membrane is made up of specialized phospholipid and it contains constant motion
the embedded molecules are also free to move around the membrane like?
rafts on a lake
since there are many other molecules embedded in it (ex: proteins ) it looks like?
a mosaic
what are the phospholipid bilayers two major functions
Biological Barrier and a Selective filter
what do the biological barriers surround in?(phospholipid bilayer)
organelles inside the cell preventing unwanted chemical reactions from happening
EX. lysosomes contain harsh digestive enzymes that could harm the cell however the phospholipid bilayer surrounding the lysosomes prevents that from happening
what does a Biological barrier do (phospholipid bilayer)
the phospholipid bilayer acts as a biological barrier separating the contents of the cell (cytoplasm) from the outside of the cell
what else does phospholipid bilayer also act as and why?
selective filter and through the phospholipid bilayer acts as a barrier it also needs to allow molecules to pass through it like water, salt and hormones
because it has the ability to
selectively filter for certain molecules it is called?
semi-permeable
certain molecules can pass through the membrane freely while others must be transported across the membrane using?
specialized transport proteins found in the membrane
the cell membrane must allow some materials to move in and out of it lists a few of these materials
water, salt and hormones
cell membranes are composed of a double layer of phospholipid imbedded with protein. the molecules that make up this double layer have a hydrophobic and a hydrophilic end. explain the difference between hydrophobic and hydrophilic
hydrophobic hate water and don’t let it in and hydrophilic love water and let it in.
since the cytoplasm and the environment surrounding a cell is most water, which of the two ends are pointed into the middle of the bilayer and away from the water?
hydrophobic
the diagram is a model of a cell membrane called the fluid mosaic model. brief;y explain why it is fluid and why it is a mosaic
the cell is made up of specialized phospholipids that make it act like a fluid. the many molecules embedded intimate it look mosair
what do the cell membranes prevent materials found in fluids outside of cells from entering
salt, viruses, sugars, proteins, ions, bacteria
what does it mean when the cell membrane is semi-permeable
allows small amounts of a substance in but not others
