cell membrane structure and function

Question 1

describe the main functions of the cell(plasma) membrane

Answer 1

controls entry of nutrients and exit of waste/secretory products, maintains ion conc., participates in joining cells, enables cell to respond to changes in cell environment

Question 2

describe the main properties of the plasma membrane

Answer 2

forms outer layer boundary of every cell, selectively permeable, fluidity

Question 3

how does the plasma membrane contribute to the functional differences between cell types

Answer 3

different functions due to variation in plasma membrane composition, different cells interact differently with the same extracellular fluid

Question 4

what are the 2 main constituents of the plasma membrane

Answer 4

lipid and protein

Question 5

describe the structure of the plasma membrane in aqueous solution

Answer 5

forms phospholipid bilayer, polar head facing outwards, non-polar tail on inside, forming 2 leaflets

Question 6

describe the fluidity of the phospholipid bilayer

Answer 6

fluid, not rigid

phospholipids are constantly moving, twirl, vibrate and move around constantly

Question 7

describe the relationship between the phospholipid bilayer and charged and uncharged molecules

Answer 7

bilayer is impermeable to charged molecules, but are permeable to small uncharged molecules

Question 8

describe the shape of the plasma membrane in an electron micrograph image

Answer 8

trilaminar appearance, 3 layers