Chapters 3.2, 4, 6

Question 1

What is the plasma membrane?

Answer 1

a fluid lipid bilayer embedded with proteins. Separates the intracellular and extracellular fluid.

Question 2

What are lipid anchored proteins?

Answer 2

proteins that are attached to the lipids by covalent bonds.

Question 3

What are channel proteins?

Answer 3

allow water soluble compounds to pass through the lipid bilayer.
have the ability to select what passes through them based on size, charge, etc.
can also open or close, dependent upon whether a ligand is present or the charge across the membrane.

Question 4

What are carrier proteins?

Answer 4

transport water soluble substances across the membrane.

highly selective.

Question 5

What are membrane-bound enzymes?

Answer 5

control reactions on either inner or outer surface.

Question 6

What are membrane receptors?

Answer 6

recognize and bind to ligands.
the ligand-receptor complex can either alter the activity within the cell, open a ligand-gated channel or promote the endocytosis of another molecule.

Question 7

What are docking proteins?

Answer 7

inner membrane proteins for secretory vesicles and initiating exocytosis.

Question 8

What are CAMs?

Answer 8

cell adhesion molecules. bind with other molecules on other cells to allow the cells to stick to each other.

Question 9

What are glycoproteins?

Answer 9

located on the outer surface of the membrane only.
MHC
self vs. nonself.

Question 10

How are cells held together?

Answer 10

collagen
elastin
fibronectin

Question 11

Describe collagen

Answer 11

protein that provides resistance to longitudinal stress

Question 12

Describe elastin

Answer 12

protein that provides elasticity

Question 13

Describe fibronectin

Answer 13

protein that provides cell to cell adhesion

Question 14

What makes up the extracellular matrix?

Answer 14

fibroblasts, which secrete collagen, elastin and fibronecti.

Question 15

Describe desmosomes.

Answer 15

adhering junction
formed by fibers
found in organs that have a high level of stress, such as skin, heart muscle and uterus.

Question 16

Describe tight junctions.

Answer 16

join sheets of epithelial tisse (forms highly selective barrier).
junctions are impermeable so substances do not slip between cells.
found in the lining of the stomach, intestines, etc.

Question 17

Describe gap junction

Answer 17

a communicating junction between cells.
allows ions to travel from cell to cell
found in heart muscles and smooth muscle.

Question 18

What molecules undergo diffusion?

Answer 18

lipid soluble substances (nonpolar) and small ions.

Question 19

What can be said about molecules in high concentration solutions?

Answer 19

they collide with each other and thus are more likely to be moving in any direction at any time.

Question 20

What is Fick’s law of diffusion?

Answer 20

Q=[dC]*[P]*[A]
     ---------------
   Sqrt[MW]*[dX]
q=net rate of diffusion
dC=concentration gradient
P=permeability
A=surface area of membrane
dX=thickness of the membrane

Question 21

What is osmotic pressure?

Answer 21

when there are solution on both sides of a membrane, but it is not permeable to the particles in the solution. Water moves from one side of the membrane to the other until concentrations of water are equal on both sides.

Question 22

What solution will have greater osmotic pressure?

Answer 22

the solution with the most water attracting solutes.

Question 23

What is osmolarity?

Answer 23

Osmolality is a property of a particular solution and is independent of any membrane.

Question 24

What is tonicity?

Answer 24

Tonicity is a property of a solution in reference to a particular membrane.