2.1.5 - biological membranes

Question 1

functions of the cell membrane

Answer 1

-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

Question 2

what is the structure of a phospholipids

Answer 2

they have 2 fatty acid tails and one phosphate group attached to a glycerol

Question 3

what is the head of the phospholipid

Answer 3

the phosphate group and glycerol molecule

Question 4

what is the tail of the phospholipid

Answer 4

the fatty acid chains

Question 5

why is the head of the phospholipid hydrophilic

Answer 5

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

Question 6

why is the tail hydrophobic

Answer 6

the fatty acid tails are repelled by water as they are non-polar

Question 7

what does amphipathic mean

Answer 7

has hydrophobic/philic elements

Question 8

how can phospholipids arrange in water

Answer 8

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

Question 9

what kind of cells does a phospholipid bilayer form in

Answer 9

eukaryotes and prokaryotes

Question 10

how does the phospholipid bilayer provide stability to the membrane

Answer 10

the phospholipids move around in the bilayer but the tail never moves into the water

Question 11

what is the cell membrane made of

Answer 11

a phospholipid bilayer with proteins in it

Question 12

what does cholesterol do in the membrane

Answer 12

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

Question 13

what is a glycoprotein

Answer 13

protein with a carb attached

Question 14

what is a glycolipid

Answer 14

lipid with a carb attached

Question 15

why do glycoproteins/lipids do

Answer 15

helps control membrane fluidity

Question 16

what does the integral proteins do in the membrane

Answer 16

involved in cell recognition, cell signalling and attachment

Question 17

what do the phospholipids do in the membrane

Answer 17

transport molecules across the membrane or catalyse reactions

Question 18

what processes is a fluid membrane used for

Answer 18

diffusion of substances across the membrane
needed for membranes to fuse or for cells to move and change shape

Question 19

what happens to the cell membrane when the temp increases

Answer 19

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

Question 20

what happens to carrier and channel proteins when the temperature is too high

Answer 20

they may denature and the tertiary structure of the protein may break down

Question 21

what can happen to the cell if the membrane fluidity increases

Answer 21

can affect the folding of the membrane during phagocytosis and the ability of cells to signal each other by releasing chemicals

Question 22

what is a monomer

Answer 22

a single subunit of life

Question 23

what are polymers

Answer 23

complex molecules formed by combining monomers using covalent bonds

Question 24

what is a condensation reaction

Answer 24

the formation of polymers from monomers

Question 25

what is the by product of a condensation reaction

Answer 25

water

Question 26

what does condensation of amino acids produce

Answer 26

proteins

Question 27

what does the condensation of monosaccharides form

Answer 27

disaccharides and condensation of disaccharides form polysaccharides

Question 28

what does the condensation of fatty acids and glycerides form

Answer 28

lipids

Question 29

what is hydrolysis

Answer 29

the break down of large biological molecules into smaller molecules because smaller molecules can be taken up by cells and used for many functions

Question 30

what does hydrolysis require.

Answer 30

water

Question 31

what does the hydrolysis of proteins produce

Answer 31

amino acids

Question 32

what does the hydrolysis of carbs produce

Answer 32

mono/disaccharides

Question 33

what does the hydrolysation of lipids produce