LABORATORY REVIEW
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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sealing of nucleotides nicks
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Synthesis of DNA strand
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Lagging strand synthesis
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All of the above
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Detailed explanation-1: -DNA ligases play an essential role in maintaining genomic integrity by joining breaks in the phosphodiester backbone of DNA that occur during replication and recombination, and as a consequence of DNA damage and its repair. Three human genes, LIG1, LIG3 and LIG4 encode ATP-dependent DNA ligases.
Detailed explanation-2: -T4 DNA ligase is an Mg2+-dependent and ATP-dependent enzyme that seals DNA nicks in three steps: it covalently binds AMP, transadenylates the nick phosphate, and catalyses formation of the phosphodiester bond releasing AMP.
Detailed explanation-3: -In DNA replication, ligase’s job is to join together fragments of newly synthesized DNA to form a seamless strand. The ligases used in DNA cloning do basically the same thing. If two pieces of DNA have matching ends, DNA ligase can join them together to make an unbroken molecule.
Detailed explanation-4: -The repair is completed by DNA ligase, an enzyme that seals single-strand nicks in double-stranded DNA.
Detailed explanation-5: -T4 DNA ligase can seal a nick in double-stranded DNA limited by a 5’-phosphorylated base-free deoxyribose residue.