2.1.5 - biological membranes Flashcards
functions of the cell membrane
-separates cell components from external
-regulates transport of substances in and out of the cell
-has antigens so the organism’s immune system recognizes it as its own
-release chemicals as signals and contains receptors for these signals
-may be the site of metabolic reactions
what is the structure of a phospholipids
they have 2 fatty acid tails and one phosphate group attached to a glycerol
what is the head of the phospholipid
the phosphate group and glycerol molecule
what is the tail of the phospholipid
the fatty acid chains
why is the head of the phospholipid hydrophilic
when phospholipids are surrounded by water, H+ ions dissociate form the phosphate group and this makes the phosphate negatively charged. this is attracted to water
why is the tail hydrophobic
the fatty acid tails are repelled by water as they are non-polar
what does amphipathic mean
has hydrophobic/philic elements
how can phospholipids arrange in water
can form a layer in the water with tails sticking out and heads in
can form micelles with tails on the inside and heads on the outside
what kind of cells does a phospholipid bilayer form in
eukaryotes and prokaryotes
how does the phospholipid bilayer provide stability to the membrane
the phospholipids move around in the bilayer but the tail never moves into the water
what is the cell membrane made of
a phospholipid bilayer with proteins in it
what does cholesterol do in the membrane
acts as a barrier to most molecules
helps to maintain fluidity of the membrane + prevents it from becoming too stiff or fluid when temps are too low/high
what is a glycoprotein
protein with a carb attached
what is a glycolipid
lipid with a carb attached
why do glycoproteins/lipids do
helps control membrane fluidity
what does the integral proteins do in the membrane
involved in cell recognition, cell signalling and attachment
what do the phospholipids do in the membrane
transport molecules across the membrane or catalyse reactions
what processes is a fluid membrane used for
diffusion of substances across the membrane
needed for membranes to fuse or for cells to move and change shape
what happens to the cell membrane when the temp increases
the phospholipids gain energy and move more. Membrane gets more fluid and loses its structure. eventually the cell will break down completely. Loss of structure leads to increased permeability meaning more particles can cross it
what happens to carrier and channel proteins when the temperature is too high
they may denature and the tertiary structure of the protein may break down
what can happen to the cell if the membrane fluidity increases
can affect the folding of the membrane during phagocytosis and the ability of cells to signal each other by releasing chemicals
what is a monomer
a single subunit of life
what are polymers
complex molecules formed by combining monomers using covalent bonds
what is a condensation reaction
the formation of polymers from monomers
what is the by product of a condensation reaction
water
what does condensation of amino acids produce
proteins
what does the condensation of monosaccharides form
disaccharides and condensation of disaccharides form polysaccharides
what does the condensation of fatty acids and glycerides form
lipids
what is hydrolysis
the break down of large biological molecules into smaller molecules because smaller molecules can be taken up by cells and used for many functions
what does hydrolysis require.
water
what does the hydrolysis of proteins produce
amino acids
what does the hydrolysis of carbs produce
mono/disaccharides
what does the hydrolysation of lipids produce
