A gel electrophoresis is performed, but when the gel imager is used, no bands appear. The researcher might have forgotten to:

Question

_____  add electric current.
_____  add antibody.
_____  ligate the DNA fragments together.
_____  include DNA dye.
_____  include an RNA probe.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

  Gather Content
· What do you already know about gel electrophoresis?

  Consider Possibilities
· Consider the different answer options. Which can you rule out?

  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
 

Answer 1

__X__  add electric current.
_____  add antibody.
_____  ligate the DNA fragments together.
__X__  include DNA dye.
_____  include an RNA probe.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses the gel electrophoresis technique.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
        o Gel electrophoresis is a technique to separate DNA fragments by size.
        o The bands represent the different size pieces of DNA.
  Gather Content
· What do you already know about gel electrophoresis?
        o Gel electrophoresis uses a soft agarose gel to separate DNA.
        o The DNA is pipetted into wells at one end; then electrical current drags the DNA through the gel.
        o The different sized fragments travel at different speeds, so they separate across the gel.
        o The bands are visualized using a DNA dye.
  Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Could the researcher have forgotten to add antibody, or an RNA probe? No, because those are not used with the simple gel electrophoresis technique.
        o Could the researcher have forgotten to ligate the DNA fragments? No. The point of a gel is to separate DNA fragments, not connect them.
  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The researcher could have forgotten to turn on the electric current – then the DNA would stay in the wells and not separate properly.
        o The researcher could also have forgotten to add the DNA dye – then the DNA would be separated, but the bands would not be visible.
  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked what could have gone wrong with gel electrophoresis.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that antibodies, RNA probes, and membranes are not involved with simple gel electrophoresis?
        o Did you realize that gel electrophoresis requires electric current, and a DNA dye?