Cell membrane and osmosis

Question 1

Properties of cell plasma membranes:

Answer 1

1. Selectively permeable
2. Fluid-like properties
   - Their structure and function are highly dynamic- called the fluid mosaic.
   - Individual phospholipid molecules can travel (by diffusion within the membrane) around the entire circumference of a cell in minutes.
3. Phospholipid bilayer that contains hydrophylic heads and hydrophobic tails.
4. Other molecules (like proteins are embedded or attached to the membrane)

Question 2

3 key functions of the plasma membrane:

Answer 2

1. Separate the internal environment from the external environment. (protection)
2. Regulate the flow of materials in and out of the cell. (regulation)
3. Interacts with other cells. (interaction)

Question 3

Receptors for extracellular signaling molecules are cell membrane proteins in 3 classes:

Answer 3

1. Ligand-gated channels= act as receptors and channels
2. G-protein coupled receptors= no chemical passes through membrane
3. Enzyme/Enzyme linked receptors= similar to G-protein-coupled receptors but more diverse.

Question 4

diffusion

Answer 4

always flows toward equilibrium

Question 5

osmotic pressure

Answer 5

h20 will move toward area with higher concentration

Question 6

all particles contribute to

Answer 6

osmotic pressure

Question 7

only charged particles contribute to

Answer 7

Electrical gradient

Question 8

Primary Active transport

Answer 8

utilizes energy in form of ATP to transport molecules across a membrane against their concentration gradient. Therefore, all groups of ATP-powered pumps contain one or more binding sites for ATP

Question 9

secondary active transport

Answer 9

uses the energy stored in these gradients to move other substances against their own gradients. As an example, let’s suppose we have a high concentration of sodium ions in the extracellular space (thanks to the hard work of the sodium-potassium pump).

Question 10

Facilitated diffusion

Answer 10

the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins

Question 11

Aquaporins,

Answer 11

also called water channels, are channel proteins, mainly facilitating transport of water between cells.