In the attached picture, it says E is the answer but I read from multiple sources that since DNA has the same charge (negative), the charge doesn't affect the rate so therefore the answer should be A. can someone explain this please?
D
deleted816661
The top of the electrode where DNA is inserted is the negatively charged cathode and the end is positively charged anode. When you run gel electrophoresis, the negatively charged DNA (because of phosphate groups) moves to the positively charged cathode. What do you mean by DNA is the same charge?
- Joined
- Mar 12, 2005
- Messages
- 5,472
- Reaction score
- 3,519
The answer is correct. It is E. The bigger the DNA, the more negatively charged phosphate groups it has, therefore stronger attraction to the anode, thus it moves faster. Furthermore, the buffer that DNA is in can play a role. If a buffer has high amount of positively charged ions, that can reduce the amount of negative charge on the DNA, thus weakening its attraction to the anode.
The size also effects the rate, because the smaller the fragment, the easier it can move throughout the Gel.
Hope this helps.
