Explorelearning.com
1
Katie Perotti
AP Bio Period 3
Student Exploration: DNA Profiling
Please sign into our ExploreLearning class and complete this worksheet while you are doing the
Gizmo. Please type your answers in the brackets ([ ]) after each question and submit this
worksheet in Google Classroom.
Vocabulary: DNA polymerase, DNA profiling, gel electrophoresis, gene, mutation, non-coding
region, polymerase chain reaction, primer, short tandem repeat
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: Get the Gizmo ready:
Forensic training ● Click on Forensic training and S
tart 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
, AP Biology Unit 6 Page 2
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).
Click Next again. The DNA segments are copied millions of times.
What do you notice about the lengths of the copied DNA strands? [ ]
5. Compare: Click Next. Gel electrophoresis is used to separate DNA strands of different
lengths. An electric current is passed through the gel. As the current moves from top to
bottom, it pulls the DNA and loading dye along with it. Click on the power box to turn it on.
Please take a screen shot and paste here ↓
A. Which person’s DNA band traveled the farthest? [ ] Shortest? [ ]
Turn on Show labels. What do you notice about the length of the DNA versus the distance it
traveled down the gel? [ ] Please take a screen shot and paste here ↓
B. Can you identify people by comparing the length of STR regions on a gel? [ ]
Explain. [ ]
6. Observe: Click Next. Then select Gene A.
A. Does gene A have any STRs? [ ] Why or why not? [ ]
1
Katie Perotti
AP Bio Period 3
Student Exploration: DNA Profiling
Please sign into our ExploreLearning class and complete this worksheet while you are doing the
Gizmo. Please type your answers in the brackets ([ ]) after each question and submit this
worksheet in Google Classroom.
Vocabulary: DNA polymerase, DNA profiling, gel electrophoresis, gene, mutation, non-coding
region, polymerase chain reaction, primer, short tandem repeat
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: Get the Gizmo ready:
Forensic training ● Click on Forensic training and S
tart 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
, AP Biology Unit 6 Page 2
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).
Click Next again. The DNA segments are copied millions of times.
What do you notice about the lengths of the copied DNA strands? [ ]
5. Compare: Click Next. Gel electrophoresis is used to separate DNA strands of different
lengths. An electric current is passed through the gel. As the current moves from top to
bottom, it pulls the DNA and loading dye along with it. Click on the power box to turn it on.
Please take a screen shot and paste here ↓
A. Which person’s DNA band traveled the farthest? [ ] Shortest? [ ]
Turn on Show labels. What do you notice about the length of the DNA versus the distance it
traveled down the gel? [ ] Please take a screen shot and paste here ↓
B. Can you identify people by comparing the length of STR regions on a gel? [ ]
Explain. [ ]
6. Observe: Click Next. Then select Gene A.
A. Does gene A have any STRs? [ ] Why or why not? [ ]
