2. Chapter 3- Cell Membrane 1

Question 1

What are the 3 types of compartmentation of cells and tissues?

Answer 1

1. Anatomical- split into cranial cavity, thoracic cavity, and abdominopelvic cavity
2. Functional- split into intracellular and extracellular fluid
3. Compartments separated by membranes- split into tissue membranes and phospholipid bilayers

Question 2

What are the four functions of the cell membrane?

Answer 2

1. Physical isolation- barrier separating ICF and ECF and cell from environment
2. Regulation of exchange with the environment- control of entry elimination and release
3. Communication between the cell and it’s environment
4. Structural support- proteins in membrane are used to make cell-to-cell connections

Question 3

What is the average composition of the cell membrane?

What is the general rule about metabolically active and number of proteins?

Answer 3

55% protein
45% lipids
Small amount of carbohydrates
But not all cell membranes are created equally these percentages are approximate

In general the more metabolically active the membrane is the more protein it contains

Question 4

What are the three types of lipids found in the cell membrane?

Answer 4

Phospholipids
Sphingolipids
Cholesterol

Question 5

What are membrane phospholipids?

What are the three structures they form?

Answer 5

Have two polar hydrophilic head groups with a nonpolar fatty acid tail inbetween the two
Can form phospholipid bilayers (sheet), Micelles (like a bilayer but a circle), and liposomes (like micelles but have an aqueous center)
Slide 12 on sept 10

Question 6

What are sphingolipids?

Answer 6

Lipid rafts

Don’t have a glycerol backbone, have sphingosine instead

Question 7

What is cholesterol?

Answer 7

Increases viscosity
Decreases permeability

Positioned between phospholipid heads to add flexibility and help make membrane impermeable to small water-soluble molecules

Question 8

What is the chemical formula of phospholipids?

Answer 8

Slide 14 on sept 10
First there’s an either ethanolamine, inositol, serine, or choline connected to a phosphate which is connected to a glycerol which is connected to two fatty acid chains

Question 9

What happens if there’s a low concentration of phospholipids?

Answer 9

They will form a mono layer at the air water interface

Polar hydrophilic portion touching water while non polar hydrophobic tails face air

Question 10

What does the extracellular surface of the cell membrane contain?

Answer 10

Glycoproteins and glycolipids

Question 11

What are integral membrane proteins compared to peripheral membrane proteins?

Answer 11

Integral membrane proteins have membrane spanning alpha helicies of about 20 amino acids
Also include transmembrane proteins AND lipid anchored proteins
Peripheral proteins are non covalently bonded with integral proteins to the phospholipid head

Question 12

What are the roles of integral proteins?

Answer 12

Membrane receptors
Cell adhesion molecules
Transmembrane movement (channels, carriers, pores, pumps)
Enzymes
Mediators of intracellular signalling

Question 13

What are the roles of peripheral proteins?

Answer 13

Participate in intracellular signalling

Form submembraneous cytoskeleton

Question 14

Where do cholesterol molecules insert themselves?

Answer 14

Into the lipid layer inbetween fatty acid chains

Question 15

What do lipid anchored proteins commonly associate with in the cell membrane?

Answer 15

They commonly associate with sphingolipids instead of phospholipids because if the high cholesterol content 3-5x more

Question 16

How do you know when it’s a lipid anchored protein?

Answer 16

When the protein stops halfway into the cell membrane in the fatty acid lipid region (it is obviously connected to the lipid portion of the phospholipid bilayer

Question 17

What are glycolipids and glycoproteins?

Answer 17

Glycoproteins are integral proteins with a carbohydrate attached, this forms a protective coat that helps with cell to cell recognition and interaction

Glycolipids are lipids with a carbohydrate attached that helps with cell to cell interactions

Use these so body doesn’t attack itself let’s white blood cells know it ain’t foreign

Slide 20 on sept 10

Question 18

What difference in females results in an overall lower body water content?

Answer 18

An increase in adipose tissue