Question

1. Draw the trinucleotide 5’ UAG 3’. This is a single stranded nucleic acid in which the three nucleotides are connected by 3’-5’ phosphodiester linkages.

2. If a double stranded DNA molecule is composed of 32% deoxyguanosine, then what is the percentage of deoxycytidine, deoxyadenosine, and deoxythymidine? What is the name of the rule used to make this calculation? (show your work)

Answer 1

Answer:

1) The structure of trinucleotide 5' UAG 3' is as below:

​2)

Rule used to perform calculations is Chargaff rule:

• ​The total number of Purine (A+G) is equal to total number of Pyrimidine (T+C)
• ​Percentage of Thymine = Percentage of Adenine (%A=%T)
• ​Percentage of Guanine = Percentage of Cytosine (%C=%G)
• ​A + T + G + C = 100%

dS DNA consists of 32% Deoxyguanosine

​Since G pairs with C, therefore the amount of cytosine (deoxycytosine) will be same as deoxyguanosine

• ​[G] = [C] = 32%
• ​Since A + T + G + C =100%
• ​(A + T) = 100 - (G+C) = 100 - (32% + 32%) = 36%
• ​Since Adenine pairs with Thymine, therefore, [A] = [T] = 36/2 = 18%

​Therefore, concentration of different deoxyguanosine is:

• ​Deoxyguanosine = 32%
• ​Deoxycytosine = 32%
• ​Deoxyadenine = 18%
• ​Deoxythymine = 18%