Lipids/proteins

Question 1

What is the freeze fracture protocol?

Answer 1

The specimen is frozen quickly in liquid nitrogen and then fractured by a sharp blow by a knife edge.

Question 2

What is the purpose of freeze fracture?

Answer 2

To split apart lipid bilayers for analysis of the membrane interior.

Question 3

What can be visualized using electron microscopy in freeze-fractured membranes?

Answer 3

Integral membrane proteins are visible in the exposed membrane interior.

Question 4

What is the difference between electron microscopy and atomic force microscopy?

Answer 4

Electron microscopy depends on scattering of a beam of electrons, while atomic force microscopy scans the sample surface using a cantilever with a sharp tip.

Question 5

What are the three important functions of membranes?

Answer 5

Transport, catalysis, and signaling.

Question 6

What role do membranes play in transport?

Answer 6

Membranes act as semipermeable barriers to the flow of substances into and out of cells and organelles.

Question 7

How do enzymes relate to membrane functions?

Answer 7

Enzymes can be bound to membranes, and enzymatic reactions can take place on the membrane.

Question 8

What is the signaling function of membrane proteins?

Answer 8

Proteins bind specific biologically important substances that trigger biochemical responses in the cell.