Cell Membranes 1

Question 1

What are the 3 body cavities?

Answer 1

Cranial cavity, thoracic cavity, abdominopelvic cavity

Question 2

Extracellular fluid?

Answer 2

Lies outside cells (blood plasma and interstitial fluid)

Question 3

What does the cell membrane separate?

Answer 3

The ICF from the ECF with a phospholipid bilayer

Question 4

What are functions of cell membrane?

Answer 4

• physical isolation (separates cell from environment)
• regulation of exchange with the environment
  -communication between the cell and its environment (proteins)
  -structural support (proteins make cell-cell connections and anchor cytoskeleton)

Question 5

What is average composition of cell membrane?

Answer 5

~55% proteins
~45% lipids
~small amount of carbs

Question 6

Why are cell membranes not created equally?

Answer 6

The more metabolically active the membrane is the more protein it contains

Question 7

What are the 3 types of lipids in cell membrane?

Answer 7

Phospholipids (~50%), sphingolipids (~30%), cholesterol (~20%)

Question 8

Why do phospholipids have hydrophobic and hydrophilic ends?

Answer 8

They are amphipathic. The polar head (hydrophilic) end arranges to be in contact with the aqueous solution but the non polar (hydrophobic) ends are not in contact.

Question 9

What are 3 ways phospholipids can arrange?

Answer 9

Phospholipid bilayer, micelles (droplets of phospholipids), liposomes (round double bilayer with aqueous center)

Question 10

How many different types of proteins are inserted into the cell membrane?

Answer 10

10-50

Question 11

What are integral proteins? Roles?

Answer 11

Transmembrane proteins, lipid anchored proteins (directly to fatty acid)
Roles: membrane receptors, cell adhesion, transmembrane movement (channels, carriers, pores, pumps), enzymes, mediators of intracellular signalling

Question 12

What are peripheral proteins? Roles?

Answer 12

Attach to integral proteins or loosely attached to phospholipid head
Roles: participate in intracellular signalling, form submembraneous cytoskeleton (linkage point)

Question 13

What are lipid rafts?

Answer 13

Large amount of transmembrane and lipid anchored proteins in this area because of elevated lipids allow more proteins to attach
Elevated regions made up of sphingolipids
High cholesterol content so stiffer

Question 14

What are lipid raft used for?

Answer 14

Important in cell signal transduction and caveolae important in endocytosis