My apologies if my question is too basic, and please point me to a more appropriate forum. I am reading the textbook "Essential Cell Biology" by Alberts et al, and am consulting other sources as well. I am reading Chapter 10 about DNA technology and have read how DNA is separated into strands of different lengths by restriction enzymes. The different size strands can then by separated by Gel Electrophoresis. I believe I understand these basics. My question is:
Do all strands of the same length have the same sequence of base pairs? I wouldn't think so, and this would be a problem in the next step, determining the sequence of one size fragment by using special base pairs that are lacking a hydroxyl group. Isn't it possible I could have two strands that are 50 base pairs long (for example) that have the same beginning and same end and are thus cut by the restriction enzymes to a length of 50, but are most assuredly not the same within their sequence
The text says that once the different size strands are separated by electrophoresis, you can just cut out one of the bands and work with that. That makes sense if you are guaranteed to only have 1 strand at that level of the gel agar or if the multiple strands are all the same exact sequence.
If you read this far, thank you. I think more generally I need to know how many of these segments are produced when you use restriction enzymes and how long the average one is. And is there any guarantee for one chromosone (or all 46 chrmosones) having all the segments be unique sizes (I wouldn't think so)?
And even more generally :), I need additional sources that explain DNA sequencing in simple to understand terms.