Why is dna chopped

Sample loading buffer for mixing with samples before running on gel available from biotechnology supply companies. UV transiluminator, for viewing gels, and camera for taking photographs of gels. Assorted laboratory equipment, such as microfuge tubes, pipet tips, etc. Marker DNA, for determining molecular weights. Each person in the scenarios will be a different type of DNA.

You can decide ahead of time which, if any, of the suspects will match the DNA found at the crime scene. By varying the matches in each scenario, student groups can be exposed to different possibilities and can compare and contrast their results.

You will place the various DNA samples in tubes labeled accordingly. Alan Greenleaf, a successful and wealthy businessman, was found shot to death in his bedroom. Nothing was stolen from the house, and there was no forced entry. Police believe he was murdered by either his wife, Karen Greenleaf, or his mistress, Lucinda Teal.

Greenleaf had been served divorce papers just days before the murder. Due to a prenuptial agreement, Mrs. Greenleaf would be left to live a lifestyle less affluent than the one to which she was accustomed once the divorce was final. Greenleaf had been seeing Lucinda Teal for almost two years before his death. Although he was not divorcing Mrs. Greenleaf to marry Ms. Teal, Lucinda still had high hopes of becoming the next Mrs. However, the romance was not going well lately, and Mr. Greenleaf and Ms.

Teal had been seen in public, having a very loud argument, several hours before Mr. Greenleaf's death. Several pieces of evidence were found at the scene of the crime, including fingerprints from Mrs. But since both women frequented the bedroom with Mr. Greenleaf, this evidence could not be used against either one. Several drops of blood were found on Mr. Greenleaf's body, possibly coming from the murderer during a struggle for the gun.

DNA was obtained from this blood sample. DNA was also obtained from each of the suspects and from Mr. Moody Blues Waters, a jazz musician, was found murdered late one night in the club at which he was headlining. Moody was a talented musician, but he found it difficult to make ends meet. He began dealing drugs to make some extra cash.

He often carried large sums of money as well as drugs wherever he went. When Moody was found, there were no drugs or money on him. If the liquid is a simple one--such as water with some salts in it--all the DNA molecules move at nearly the same speed.

Under those conditions, it is hard to distinguish the tiny disparities in the motion of different kinds of DNA. Usually smaller DNA molecules move faster than larger ones. After a while, the molecules are separated by size. If the molecules fall into only a few discreet sizes, then bands little rectangles of DNA will appear in the gel. Each of these bands contains DNA strands of a specific size.

The human DNA molecules are treated with enzymes that chop them at certain characteristic points, thereby reducing the DNA to a collection of more manageably sized pieces.

Other restriction enzymes, like Eco RI , cut through the DNA strands at nucleotides that are not exactly opposite each other. This creates DNA fragments with one nucleotide strand that overhangs at the end. This overhanging nucleotide strand is called a sticky end because it can easily bond with complementary DNA fragments. Add to collection.

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