Identify the unknown and explain your answer, describing the principle of the te

Question

Identify the unknown and explain your answer, describing the principle of the test performed and how you came to your conclusion. In the above example, while performing the Seliwanoff test a student forgot to stop the reaction in time and heated the unknown sample for 7 min, when the sample showed a change/red color. What do you think happened? The following samples DNA, RNA, deoxyguanosine, adenosine, cytidine and ribose, were treated with the Dische reagent. State the principle of the Dische test and explain the expected results for each of the above samples. What do you expect to see when cytidine is treated with Bials reagent? Why? Given below is the restriction map of a plasmid molecule. The plasmid DNA was treated with the Pstl and BamHI as follows. 1. Pstl 2. BamHl 3. Pstl and BamHl Calculate the expected number and sizes of DNA fragments obtained. Why do EcoRI and Hindlll enzymes give rise to cohesive or sticky ends?

Explanation / Answer

Q. 5b: Eco-R1 & Hind-III enzymes assymetrically cut the double stranded DNA at it recognised site. So they can produce cohessive or sticky or staggered ends

5'---------------------------------------3' 5' -----------------------------------3' 5'----------3'

----E.co-R1 or Hind-III---->

3'----------------------------------------5' 3'-----------5' 3'-----------------------------------5'

Q5. a. 1. pst-1 digestion gives single band length of 4361bp; 2. Bam-H1 digestion gives single band length of 4361bp; 3. Two bands with approximate sizes of 1000bp & 3300 bp

Q4.a. Dische test is a diphenyl amine test, in which it reacts with deoxy ribose and gives blue color upon heating. Compounds that contain deoxy ribose like DNA, Deoxy guanosine will only give DISCHE test positive. All other cannot develop blue color due to lack of Deoxy ribose

Q4. b. The test reagent dehydrates pentoses to form furfural. Furfural further reacts with orcinol and the iron ion present in the test reagent to produce a bluish product. As cytidine is nucleoside, it contain pentose sugar, it reacts and gives color

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