1. The sample that contains DNA from the person who committed the crime is the "Crime scene" sample, as it matches the DNA fingerprint of one of the suspects (Suspect 3).
2. The positive side of the DNA fingerprint is the side where the DNA is loaded into the wells (the top of the gel), marked with a + sign. The negative side is the opposite end (the bottom of the gel), marked with a – sign.
3. DNA is loaded at a specific end of the gel (the negative end) because DNA is negatively charged due to its phosphate backbone. When an electric current is applied, the DNA migrates toward the positive electrode. Placing the DNA at the negative end ensures it moves through the gel toward the positive end, allowing separation by size.
1. Dog species 1 is most closely related to the common ancestor because it has the most bands in common with the common ancestor, indicating fewer genetic changes have occurred.
2. Dog species 3 has the smallest DNA fragment because it has the band that migrated the furthest toward the positive end of the gel, indicating it is the smallest in size.
3. A loading dye must be added to the DNA before it is placed in the wells so it separates out into different bands. The loading dye helps visualize the DNA and ensures it sinks into the wells properly.
Parent Tip: Review the logic above to help your child master the concept of dna fingerprint worksheet.
