I need help with bio question ?

Question

If you used primers of 2 different sequences in a sequencing reaction, fragments of the same length could end in 2 different colors. EXPLAIN.

Answer 1

Assuming you are talking about the chain termination method of sequencing, there is a very easy explanation. Chain termination determines sequence by introducing ddNTP or dideoxynucleotides. When a dideoxynucleotide base is added to a growing chain in place of a regular base the elongation process terminates. This is because it is a dideoxy base. When it lacks the required oxygen for the hydrolysis reaction in elongation, the process cannot continue. Each ddNTP (ddATP, ddGTP, etc) has a radioactive marker on it that corresponds to a different color.

You said the primers are of different sequences and result in fragments of the same length. Well because you are dealing with different sequences it makes sense that fragments of the same length will not necessarily end in the same base. There is therefore a 1 in 4 chance that the colors will be different.