diffusion and the cell membrane

Question 1

simple diffusion def

Answer 1

the movement of molecules from high to low concentration directly over the phospholipid bilayer of a membrane

Question 2

facilitated diffusion def

Answer 2

the movement of molecules from high to low concentration with the help of proteins

Question 3

what are the properties and structure of phospholipids

Answer 3

They are composed of a hydrophilic head and a hydrophobic tail. The hydrophobic tails clump on the inside of the membrane whilst the hydrophilic heads form strong attractions with polar water molecules.

Question 4

what are some parts of the cell membrane

Answer 4

phospholipid bilayer- basically are the membrane
cholesterol- helps stabilize the membrane
proteins- help with the process of facilitated diffusion
membrane carbohydrates (glycolipids and glycoproteins)- play a key role in cell-cell recognition, organ and tissue development, and basis for rejection of foreign cells by immune system

Question 5

why is the surface area: volume ratio important?

Answer 5

diffusion works best over small distances. It would take a lot more time to diffuse a basketball to its center than it would a tennis ball. This is the same concept. It is best to have a lot of surface area with as little volume as possible. The reason by certain creatures are larger isn’t because they have necessarily larger cells, but just more cells.

Question 6

True or False:
the phospholipid bilayer is composed of a hydrophobic head and a hydrophilic tail

Answer 6

false; it is the other way around

Question 7

True or False:
there is only one kind of protein used for facilitated diffusion

Answer 7

false; there are all different kinds of proteins for each different molecule that needs to enter the membrane