Wright 1 - Electrophoresis Flashcards
What is the positive electrode called?
The anode
What is the negative electrode called?
cathode
DNA moves in what direction in electrophoresis? Which electrode to which electrode?
From the cathode (-) to anode (+)
What is agarose?
An uncharged polysaccharide purified from agar of the seaweed Agar ager. To prepare it agar is harvested in the sol state and heated to make the initial gel and then aged to make the final gel structure
What type of filter must be placed below a gel when UV light is shined onto it from below?
Transiluminator filter
How do linear DNA molecules migrate through gel? (eg at what rate?)
At a rate that is inversely proportional to the log of their molecular mass or base pairs
What three parameters influence the rate of migration of DNA molecules during gel-electrophoresis?
- Percentage of agarose in gel-matrix
- Topology (conformation) of the DNA molecule: linear, relaxed circular, or supercoiled
- The voltage applied (<5 volts/cm)
How does agarose concentration effect DNA molecule migration?
- Higher concentration decreases average pore size
- Smaller pore size cause less DNA migration and effects the separation range of linear DNA molecules
How can separation range of DNA be changed in electrophoresis?
By altering agarose concentration
What are the three topologies that DNA molecules can take?
- Linear
- Relaxed circle
- Supercoiled circle
What is the most common type of supercoil in DNA?
Negatively supercoiled
How can positively supercoiled DNA be observed?
in vitro
Rank the topologies of DNA from least distance migrated to most distance migrated
Least distance
- Relaxed circular
- Linear
- Supercoiled
Does %GC content influence rate of migration of DNA molecules during agarose gel electrophoresis?
no
What do restriction endonucleases do for bacteria and some yeast?
Prevent infection by DNA viruses
