PLSC 631 - Intermediate Genetics
Cloning and Molecular Analysis of Genes Quiz
1. You have isolated plasmid DNA from an E. coli cell that has a mutation in the EcoRI methylase gene. You are next given three unlabed tubes of enzymes and are told that these enzymes are components of two restriction-modification systems. You next perform a series of experiment in which you sequentially add enzymes to a reaction mixture. From the data below determine which tube contains the methylase and which tube contains the associated restriction enzyme. | Reaction | First enzyme
from tube: | Second enzyme
from tube: | Reaction
Products |
| 1. | 1 | 2 | Uncut DNA |
| 2. | 1 | 3 | 1.0 and 3.0 kb
bands |
| 3. | 2 | 1 | 1.5 and 2.5 kb
bands |
| 4. | 2 | 3 | 0.2, 0.3, 1.0
and 2.5 kb bands |
| 5. | 3 | 1 | 1.0 and 3.0 kb
bands |
| 6. | 3 | 2 | 0.2, 0.3, 1.0
and 2.5 kb bands |
2. How does cDNA cloning differ from developing a genomic library?
3. When you screen a library, you first add a radioactive probe to a solution that will bathe the filters upon which clones of the library are immobilized. You next perform a series of washes at different temperatures. How will the use of a homologous or heterologous probe affect your decision regarding the temperature you will use to wash the filters?
4. Discuss in a paragraph the differences between northern and southern hybridizations.