1
Question
The role of DNA ligase in the construction of a recombinant DNA molecule is:
The role of DNA ligase in the construction of a recombinant DNA molecule is:
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Solution
The correct option is D Formation of phosphodiester bond between two DNA fragments
Formation of phosphodiester bond between two DNA fragments:
DNA ligase is the enzyme that creates the phosphodiester bond between the nucleotides of DNA fragments and joins them together. To create a recombinant DNA molecule, DNA ligase is used to join DNA of interest and vector DNA.
Formation of hydrogen bonds between sticky ends of DNA fragments:
The cuts are made by breaking the phosphodiester bond between two specific adjacent nucleotides of a strand. This results in the formation of two single stranded ends of DNA that will have some nucleotides without any complementary bases. When complementary sticky ends of DNA fragments meet, hydrogen bonds are formed between the complementary bases which results in annealing of the ends of the fragments. The occurrence of this reaction does not need the catalytic influence of any enzyme.
Ligation of all purine and pyrimidine bases:
Each nucleotide of a DNA strand has either a purine or a pyrimidine base attached to the 1st carbon of the pentose sugar. These nitrogenous bases project towards the inner side of the double helix. Purines and pyrimidines of each strand pair up with the complementary bases on the complementary strand via hydrogen bonds, thus holding the two strands of the helix together.
Final answer
a. Formation of phosphodiester bond between two DNA fragments
Formation of phosphodiester bond between two DNA fragments:
DNA ligase is the enzyme that creates the phosphodiester bond between the nucleotides of DNA fragments and joins them together. To create a recombinant DNA molecule, DNA ligase is used to join DNA of interest and vector DNA.
Formation of hydrogen bonds between sticky ends of DNA fragments:
The cuts are made by breaking the phosphodiester bond between two specific adjacent nucleotides of a strand. This results in the formation of two single stranded ends of DNA that will have some nucleotides without any complementary bases. When complementary sticky ends of DNA fragments meet, hydrogen bonds are formed between the complementary bases which results in annealing of the ends of the fragments. The occurrence of this reaction does not need the catalytic influence of any enzyme.
Ligation of all purine and pyrimidine bases:
Each nucleotide of a DNA strand has either a purine or a pyrimidine base attached to the 1st carbon of the pentose sugar. These nitrogenous bases project towards the inner side of the double helix. Purines and pyrimidines of each strand pair up with the complementary bases on the complementary strand via hydrogen bonds, thus holding the two strands of the helix together.
Final answer
a. Formation of phosphodiester bond between two DNA fragments
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