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Transcript of DNA Profiling
A technique used by forensic scientists to help identify individuals by their DNA profiles.
DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can be used to identify people.
Used in parental investigation and criminal investigation. Essential Bio Questions 2. State the two main uses of DNA profiling by electrophoresis.
to determine paternity relationships
as evidence in criminal cases
3. State some other names for DNA profiling.
4. State the roles of the following components of gel electrophoresis:
Restriction enzymes - Cut DNA into fragments.
Gel - DNA sample is placed in gel.
Electric current - passed through; pushes the fragments
Fluorescent DNA markers - binds to triplet in the DNA fragments By Sierra Nadle, Katie Ryan, Hannah Shanley, and Madison Freeman DNA Profiling DNA Profiling Steps 1. DNA fragments using restriction enzymes.
2. Separating DNA fragments using gel electrophoresis.
3. Retrieve DNA fragments from gel.
4. Radioactive DNA hybridization. DNA Profiling History Developed by two independent breakthroughs.
The polymerase chain reaction (PCR) was invented by Kary Mullis.
Sir Alec Jefferys discovered DNA fingerprinting.
The first DNA profiling conviction was made in in 1986.
Used to solve two rape/murders that happened three years apart in Leicestershire, UK.
The method of DNA profiling we recognize today was developed after words in the late 1980s and early 1990s. Step 1 Restriction Enzyme.
Recognizes specific sequence of bases of the DNA.
Cuts the DNA strand into recognition sequence.
Cuts between the center of G and C. Step 2 Gel Electrophoresis.
Separates the fragments according to size.
DNA sample is placed on one side of gel then an electric current is applied.
* DNA is a negatively charged particle.
Why use the gel?
The negatively charged particle moves towards the positive electroids in the gel chamber.
Agarose Molecules in Gel.
Sift out small fragments so that easy identification of DNA can occur. Step 3 Nylon Filter.
Allows distinction between DNA of individuals.
Identifies specific pattern in inherited alleles.
DNA double strands are separated and the filter will only contain single stranded DNA.
* Filter only contains single stranded DNA so a complementary sequence could be identified. Step 4 Variable Number Tandem Repeats.
Single strand DNA is radioactively labeled and recognize certain sequences of DNA.
Randomly repeated throughout the genome.
VNTR from one parent.
a homologous but not identical VNTR from the other parent. Quiz Questions Video Essential Biology Questions Cont. 5. Annotate the image below to outline briefly how gel electrophoresis works, including how the size of the fragments affects their position on the final gel. Essential Biology Questions Cont. 6. Use the gel electrophoresis results below to answer these questions.
In this case, a DNA Sample was taken from a cigarette found at a crime scene (smoking in a no-smoking zone):
a. State the process used to amplify the small amounts of DNA collected at the crime scene to an amount big enough to be used in DNA profiling.
Polymerase chain reaction.
b. Deduce which criminal, Rob, McCarr or Nick Allott, left their dribbly cigarette-end at the crime scene. Explain your answer.
Criminal: Rob McCarr.
Explanation: Because the DNA found at the crime scene is identical to Rob's.
c. Draw bands to show where the standard fragments would be observed. State the role of the standard fragment.
Is used to show all the possible DNA fragments.
d, Outline the evidence in the DNA profile that suggests Nick and Rob are related.
Nick and Rob share four bands. 1) What is the charge of agarose gel?
2) why is this significant in regards to DNA?
3) Why does the nylon filter only contain single strand DNA?
4) What is the sequence called that we try to identify in splitting the DNA?
5) Who founded DNA profiling?