form and function of plasma membrane (unit 2)

what is the function of a plasma membrane?

control traffic into and out of cell, has selective permeability

what was the first model of the membrane proposing it was made out of? why?

Charles Overton proposed that membranes are made out of lipids, because lipids went through them easily

what is an amphithatic molecule?

molecule that has both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, allowing it to interact with both polar and non-polar substances.

how did the research of the membrane lead to the fluid mosaic model?

it was then proposed thatt phospholipids in the membrane were arranged in a bilayer. Then it was noticed that phospholipids do not actually adhere well to water which led to the fluid mosaic model which is amphipathic

what can pass through membranes easily?

small non-polar things, lipids, hydrocarbons, hormones

what cannot pass through a membrane?

large polar molecules (most sugars), ions

how do things that usually cannot come into the cell pass through the membrane?

they have to use a transport protein to get into the cell