Question

Describe the steps a scientist would use to make a dna fingerprint from the cells found beneath a murder victim's fingernails

Answer 1

The creation of a DNA fingerprint involves extracting DNA from a sample, using PCR to amplify it, applying the mixture to an agarose gel, separating the DNA fragments via gel electrophoresis, and then staining the bands to visualize the unique DNA pattern.

Step-by-step explanation:

Steps for Creating a DNA Fingerprint

Creating a DNA fingerprint from cells found beneath a murder victim's fingernails involves several steps. The process begins with the extraction of DNA from the cells. Here's a detailed breakdown of the entire procedure:

1. Extract DNA from the sample found under the fingernails, which could include blood, skin, or other body fluids.
2. Mix the extracted DNA with restriction enzymes and amplify fragments using Polymerase Chain Reaction (PCR).
3. Apply the DNA and restriction enzyme mixture into the wells of an agarose gel.
4. Connect the gel to a power source to create an electric current, allowing for gel electrophoresis.
5. The negatively charged DNA fragments move towards the positive electrode, with larger fragments moving slower and thus remaining near the top of the gel, while smaller fragments move faster towards the bottom.
6. Stain the separated DNA bands to visualize the different sizes, which are indicative of the unique DNA pattern of an individual.

These DNA patterns are compared against known samples to match individuals to the DNA found at the crime scene, confirming or excluding suspects based on the genetic evidence.

Answer 2

The steps of taking a genetic fingerprint on a crime scene are:

* Samples are first taken from the crime scene. -> DNA sampling

Samples arriving at the laboratory under seal are treated independently of each other by scientists.

* The biological sample undergoes a first treatment that consists in extracting all the DNA. -> DNA extraction

* The DNA is analyzed and the results are interpreted. -> RFLP (restriction fragment length polymorphism) technique and electrophoresis, as well as PCR.

The laboratories authorized to carry out the analyzes relating to the human genetics are chosen with the greatest care by a commission of approval which applies draconian specifications to verify scrupulously the conformity of the equipment of the places.