DNA Profiling 2020 Gizmos worksheet.pdf

Gizmo Warm-up DNA profiling does not just compare people’s entire genome side by side. Instead, a very particular part of the DNA is compared. In the DNA Profiling Gizmo you will learn about the differences in DNA that make DNA profiling possible and you will use that knowledge to design your own DNA profiling test. Click on the crime lab in the Forensic training section. You are looking at a strand of DNA at the top of the screen. DNA contains genes and non-coding regions between genes. Click on Non-coding A. 1. You are looking at a portion of the non-coding A section for three different people. Are these sections the same or different? [The three individual strands are the same up until the 14th code.] Explain. [Person number 2 only has 2 STRs while person number 1 has 4 and person number 3 has 3, making the sections different.] (you may want to click on “Show STR”) 2. Click Previous then click on Gene A. Are there differences in gene A for the three people? [yes] Why do you think the coding Gena A are different or all the same for the 3 people? [ I think they are different because person 2’s sequence of nucleotides has a mutation. Since they are all coding for the same gene the sequence should be identical, unless there is a mutation, which is found in person 2.] Activity A: Forensic training Get the Gizmo ready: ● Click on Forensic training and Start again. Read this → Introduction: In this activity, you will learn about the principles and techniques that make DNA profiling possible. Genes code for specific traits. In people, the DNA sequences for most genes are nearly identical, since any change could result in a harmful disorder. The areas between genes do not code for any essential traits, so a change to the DNA sequence doesn’t have any major consequences. As a result, these regions tend to be very different for different people. Question: How can the differences in DNA be exploited to perform DNA profiling? 1. Observe: Click on non-coding A. What do you see in the middle of each of the three DNA sequences? [ ] 2. Compare: Turn on Show short tandem repeats (STRs). An STR is a short, repeated sequence of DNA, like TAAA. They can be repeated any number of times without affecting the traits of the person. Different people usually have different numbers of repeats. What does this do to the length of each person’s non-coding regions? [ ] 3. Create: Your goal is to make copies of the STR region. To do this, you will make primers that surround the STR region. A primer is a short sequence of DNA that acts as a starting point for DNA replication. Click Next. Click on person 1’s DNA to separate the two strands. Drag along the AAGGC nucleotides, and then the TCGCC nucleotides to create primers. Click Next. The Gizmo will add the same primers to the two other people. What do you notice about where the primers attach in each person? [ ] Why do you have to drag each strands in opposite directions to add the primers? [ ] 4. Observe: Click Next. An enzyme called DNA polymerase uses the primers as a starting point to copy the DNA. Copying DNA using primers is a technique called Polymerase chain reaction (PCR). ...............CONTINUED...................