DNA BIOTECHNOLOGYDNA BIOTECHNOLOGY

Bio 102 LabBio 102 Lab

DNA ELECTOPHORESIS

This technique uses an agarose gel made from purified seaweed.

It is used to separate DNA molecules according to their length.

The gel is submersed in a tank filled with a salt solution The gel is submersed in a tank filled with a salt solution that conducts electricity.that conducts electricity.

DNA samples are loaded into slots DNA samples are loaded into slots made in the agarose gel.made in the agarose gel.

DNA molecules snake through the gel which has pores in it DNA molecules snake through the gel which has pores in it that tangles up the larger DNA fragments. The smaller that tangles up the larger DNA fragments. The smaller

fragments migrate faster and further.fragments migrate faster and further.

A fluorescent dye is added to stain the DNA so it will glow A fluorescent dye is added to stain the DNA so it will glow when placed under ultraviolet light.when placed under ultraviolet light.

A photograph can then be taken of the gel plate for analysis A photograph can then be taken of the gel plate for analysis and documentation.and documentation.

DNA PROFILINGDNA PROFILING

INVESTIGATE A ROBBERYINVESTIGATE A ROBBERY

THE CRIMETHE CRIMEA woman was hit on the head in her home by a thief who escaped with her money and jewelry. She recovered from her injuries but cannot remember what the thief looks like.

You will examine DNA from blood and hairs from the crime scene and DNA from blood samples from the victim, her husband, and a suspect. Then you will try to establish whether the suspect was at the scene.

First, the DNA was extracted from the First, the DNA was extracted from the blood and the hair samples and placed in blood and the hair samples and placed in test tubes.test tubes.

Here is the equipment for electrophoresis.

The solution in each dropper contains the DNA. The droppers load the DNA samples into the gel.

The scale measures the length of each DNA strand.

When the electrical current is applied, the DNA strands travel down the plate. The larger ones are towards the top and the smaller ones get all the way through to the bottom.

Which DNA sample matches the blood sample from the crime scene?

Does the DNA evidence place the suspect at the scene of the crime?

INVESTIGATE A WILLINVESTIGATE A WILL

Percy Davis has just died, leaving his vast fortune to his children, Percy Junior and Ann. A man named Alistair claims that he too is one of Percy’s children and demands his share of the money.

You will examine DNA from Percy, his wife Harriet, Percy Junior, Ann, and Alistair to try to establish whether Alistair has any basis for his claim.

DNA samples from each person are loaded into the wells.

The DNA fragments are drawn through the gel by electric current.

If the bands for two people have moved the same distance, there is a match of DNA at this site.

Which bands from Harriet match the bands of Percy Junior?

The bands highlighted in Harriet’s profile match the bands in Percy Junior’s profile.

Those are the DNA fragments that he inherited from his mother.

Which bands from Percy match the bands of Percy Junior?

The bands highlighted in green are the DNA strands that Percy Junior inherited from his father.

You can see that Percy Junior has inherited half of his DNA from each of his parents.

Now look at the profiles for Alistair and An to see if they also inherited half of their DNA from Percy and Half from Harriet.

Is Percy the father of all three children?

Is Harriet the mother of all three children?

Who is not Harriet’s child?

Does Alistair have a basis for his claim for part of Percy’s fortune?

ReferencesReferences

http://www.dnalc.org/ddnalc/resources/elehttp://www.dnalc.org/ddnalc/resources/electrophoresis.htmlctrophoresis.html

http://www.biotechnologyonline.gov.au/pohttp://www.biotechnologyonline.gov.au/popups/int_dnaprofiling.cfmpups/int_dnaprofiling.cfm