If two DNA samples show the same band pattern, what does that indicate?

If two DNA samples show the same band pattern, what does that indicate?

• A. Same DNA
• B. Different DNA
• C. More abundant DNA
• D. Contamination present

Answer: (A)

When DNA is analyzed by separating fragments by size, the pattern of bands you see acts like a fingerprint for that DNA. If two samples show the same bands at the same positions, the fragments from both samples have the same lengths, which means they come from the same DNA source. In other words, the two samples are the same DNA (identical in the regions examined), with identical twins being a notable exception since they share the same pattern too. The other possibilities don’t fit because different DNA would produce different fragment sizes, more or less DNA won’t create a new pattern (it changes band intensity, not which bands appear), and contamination would usually add extra bands or distort the pattern rather than replicate it exactly.

When DNA is analyzed by separating fragments by size, the pattern of bands you see acts like a fingerprint for that DNA. If two samples show the same bands at the same positions, the fragments from both samples have the same lengths, which means they come from the same DNA source. In other words, the two samples are the same DNA (identical in the regions examined), with identical twins being a notable exception since they share the same pattern too. The other possibilities don’t fit because different DNA would produce different fragment sizes, more or less DNA won’t create a new pattern (it changes band intensity, not which bands appear), and contamination would usually add extra bands or distort the pattern rather than replicate it exactly.