transport across membranes

Question 1

what is a phospholipid?

Answer 1

2 fatty acids attached to a glycerol molecule attached to a phosphate group. looks like an egg with tails kind of. it has a hydrophilic head and hydrophobic tail

Question 2

what is the phospholipid bilayer?

Answer 2

it is two layers of phospholipid, forming the cell surface membrane. the hydrophobic fatty acid tails face each other while the hydrophilic heads face outwards

Question 3

explain the fluid mosaic model

Answer 3

due to weak hydrophobic interaction in the phospholipid. unsaturated fats have double bonds which do not allow close packing of phospholipids

Question 4

what is simple diffusion?

Answer 4

uncharged, small & lipid-soluble substances moving from a higher conc to a lower conc

Question 5

what is facilitated diffusion?

Answer 5

ions & large polar substances moving from a higher conc to a lower conc with the use of channel/carrier proteins

Question 6

what is active transport?

Answer 6

against a concentration gradient (lower to higher conc), using energy in the form of ATP, involves protein pumps at the membrane

Question 7

what is bulk transport?

Answer 7

vesicles of matter, requiring ATP, moves from a higher to lower conc (endocytosis = in, exocytosis = out)

Question 8

what is osmosis?

Answer 8

net movement of water molecules from a higher to lower conc across a selectively permeable membrane