In 1968, Dr. Werner Arber at the University of Basel, Switzerland and Dr. Hamilt
ID: 142918 • Letter: I
Question
In 1968, Dr. Werner Arber at the University of Basel, Switzerland and Dr. Hamilton Smith at the Johns Hopkins University, Baltimore, discovered a group of enzymes in bacteria, which when added to any DNA will result in the breakage (hydrolysis] of the sugar-phosphate bond between certain specific nucleotide bases [recognition sites). This causes the double strand of DNA to break along the recognition site and the DNA molecule becomes fractured into two pieces. These molecular scissors or "cutting enzymes are restriction endonucleases. Two common restriction enzymes (endonucleases) are EcoRI and Pstl which will be provided to you in this lab procedure. To better understand how EcoRI and Pstl may help you in performing your DNA fingerprinting experiment, first you must understand and visualize the nature of the "cutting" effect of a restriction endonuclease on DNA: ATGA ATTCTCAATTACCT TACTTAAG AGTTAATGG A sticky ends blun tends The line through the base pairs represents the sites where bonds will break if the restriction endonuclease EcoRI recognizes the site GAATTC. The following analysis questions refer to how a piece of DNA would be affected if a restriction endonuclease were to "cut" the molecule in the manner shown above. DNA 1. How many pieces of DNA would result from this cut? 2. Write the base sequence of the DNA fragments on both the left and right side of the cut Left Right: 3. What differences are there in the two pieces? Student Manua 25Explanation / Answer
Answer :-
5'-ATG-3'___
3'-TACTTAA-5'
Right:
5'-AATTCTCAATTGGA-5'
___3'-GAGTTAATGGA-5'
Above are the base sequence of DNA fragments of both the left and right side of the cut.
After the cut, two DNA fragments are formed with sticky ends.
You should know the directionality of the fragments as it is important.
3.The difference between the two piece is that each fragment having a different size.