3.6.3 Freeze Fracture and Differential Centrifugation Flashcards
1
Q
freeze fracturing
A
- has been developed mainly for the study of
cells and cell organelle structure - During the process, a frozen specimen is split under a vacuum and then shadowed with a platinum/carbon mix, resulting in a replica of the fractured surface. Generally when cells are subjected to the technique, freeze fracture lines occur along the hydrophobic inside of any cell membrane. Looking at the picture, you can see various surfaces of organelle membranes.
2
Q
differential centrifugation
A
- involves the separation of cellular particles according to their mass, size, or density.
- Different organelles of the cell differ from each other in size and weight and sediment at different rates when subjected to centrifugal force.
- Each time a mixture is spun at a given rate, heavier materials will drop to the bottom. The bottom material is called the pellet. Once the pellet is removed, the rest of solution is called the supernatant.
- The solution is subjected to faster speeds until all of the material is collected.
3
Q
When a lipid bilayer is subjected to freeze fracturing, it is split in half. The bumps that are present on the exposed surfaces are due to
A
- transmembranal proteins
4
Q
True or false?
Differential centrifugation involves the separation of cellular particles according to their mass or density.
A
- true
5
Q
Match the descriptions below with the proper terms:
- Material on the bottom of the tube after centrifugation.
- Process by which materials fall out of solution.
- Portion of solution containing suspended material.
- Procedure that capitalizes on differences in sedimentation rates.
A
- Pellet
- Sedimentation
- Supernatant
- Differential centrifugation
6
Q
A centrifuge is most similar to which carnival ride?
A
- round-up
7
Q
If a cell membrane undergoes freeze fracture, the __________ is closest to the exterior and the __________ is closest to the cytoplasm.
A
- E face; P face
