5.1.1 Cell Membrane Components

Question 1

Chemical components of Membranes

Answer 1

Lipids and Proteins

Question 2

Types of membrane lipids + Roles

Answer 2

Glycerophospholipids - Primary lipid that structures a cells.
Cholesterol - Regulates fluidity of membrane

Question 3

Membrane structural characteristics

Answer 3

Phospholipid bilayer and water insoluble. Hydrophobic molecules pass through, or small polar (like urea).

Question 4

What is the membrane “solubility problem” for pharmaceuticals?

Answer 4

compounds have to be water soluble to be transported by blood and also insoluble to pass through cell membranes.

Question 5

What determines rate of diffusion through membrane?

Answer 5

The diffusion constant, which is based on size, polarity and viscosity.

Question 6

Types of membrane proteins

Answer 6

Integral: Proteins imbedded into the cell membrane by hydrophobic domains such as a-helices and b-sheets.
Peripheral: Proteins not imbedded, instead relying upon hydrophobic groups/molecules to stay on membrane surface.

Question 7

Types of Integral Membrane Proteins

Answer 7

Monotopic and Ditopic.

Question 8

What is used to wash Integral Membrane Proteins?

Answer 8

Detergents, which are amphipathic molecules that can cross the membrane.

Question 9

Integrins

Answer 9

Ditopic integral membrane proteins that anchor the cell to another cell in extracellular matrix.

Question 10

7TM Receptors

Answer 10

Seven Transmembrane Receptor, which acts as a signal transducer. Uses 7 a-helices to anchor.

Question 11

C1 and C2 kinase domains

Answer 11

Peripheral Membrane Proteins that recognize and attach proteins to phospholipids.

Question 12

Types of Transporters

Answer 12

Symporter: Couples the transportation of one molecule with another both into the cell.
Uniporter: Transports specific types of molecules, either in or out.
Antiporter: Exchanges molecules to maintain electrical equilibrium. one out, one in.

Question 13

What is used to wash Peripheral Membrane Proteins?

Answer 13

Salts, Acids/Bases, and specific molecules like urea.

Question 14

Active Transporters + Example

Answer 14

Use ATP, usually against concentration gradient.

Ex: Gastric proton pump to maintain stomach pH.

Question 15

Secondary Active Transporters + Example

Answer 15

Powered by electrical gradient (ion diffusion)

Ex: Sodium/Chloride symporter in kidneys reabsorbs sodium and chloride from tubular fluid.

Question 16

Passive Transport

Answer 16

Allows certain molecules to naturally diffuse into the cell.
If transporter uses a gate, it is called a channel.