Cell surface membranes- plasma membranes

Question 1

function (5)

Answer 1

• acts as a selectively permeable barrier
• provides structure (keeps cell together)
• allows communication w other cells
• allows mobility in some organisms
• site of various reactions

Question 2

made up of % wise

Answer 2

-45% phospholipids, 45% proteins, 10% ( cholesterol, glycolipids, glycoproteins)

Question 3

how many ester bonds in phospholipid

Answer 3

-2 because of 2 tails

Question 4

diff in shape between a saturated fatty acid + unsaturated

Answer 4

-If fatty acids are unsaturated, their shape is altered from a saturated molecule so the molecules in the Lipid push apart (kinks), thus making it more fluid and oily

Question 5

role of cholesterol in membranes

Answer 5

bind to the hydrophobic tails of the phospholipids=pack more closely together
-this makes the membrane less fluid and more rigid

Question 6

role of glycoproteins and glycolipids in membranes

Answer 6

• stabilise the membrane by forming hydrogen bonds with surrounding water molecules
• the sites where drugs, hormones and antibodies bind
• act as receptors for cell signalling
• theyre antigens (involved in immune response)

Question 7

how do cells communicate with each other

Answer 7

• one cell releases a messenger molecule e.g a hormone
• molecule travels to another cell
• detected by the cell because it binds to a receptor on its cell membrane

Question 8

role of proteins in the membrane

Answer 8

• some form channels which allow small or charged particles through
• other (carrier proteins), transport molecules and ions across the membrane by active transport and facilitated diffusion
• also act as receptors (membrane bound receptors)

Question 9

how do receptor proteins work

Answer 9

receptor proteins have specific shapes, only messenger molecules with a complementary shape can bind to them

Question 10

example of messenger molecule and what it binds to

Answer 10

• glucagon= a hormone thats released when there isnt enough glucose in the blood.
• binds to receptors on liver cells, causing liver cells to break down stores of glycogen and glucose

Question 11

example of antihistimines

Answer 11

• cell damage causes release of histamine which binds to receptors on surface and causes inflammation
• antihistamines work by blocking histamine receptors on cell surfaces which prevents histamine from binding= stops inflammation