Okazaki fragments are joined to form continuous strands of DNA by which of the following enzyme?
Ans. C. DNA Ligase. (Ref Harper 28th/324; Satyanarayan Biochemistry 3rd / page no 526)Okazaki pieces are later joined to form continuous strands of DNA. DNA Polymerase-I & DNA ligase are responsible for it.DNA replication: Eukaryotic DNA replication is more complex than the prokaryotic process but uses many enzymes analogous to those listed below. In both prokaryotes and eukaryotes, DNA replication is semiconservative and involves both continuous and discontinuous (Okazaki fragment) synthesis.1HelicaseUnwinds DNA template at replication fork.2Single-stranded binding proteinsPrevent premature reannealing of dsDNA3DNA topoisomerasesRelieve torsional strain that results from helicase-induced unwinding. Creates a single- or double-stranded break in the helix to add or remove supercoils.Fluoroquinolones--inhibit DNA gyrase (prokaryotic topoisomerase II).4PrimaseInitiates synthesis of RNA primers. Thus, Makes an RNA primer on which DNA polymerase III can initiate replication.5DNA polymerasesDeoxynucleotide polymerization6DNA polymerase IIIProkaryotic only. Elongates leading strand by adding deoxynucleotides to the 3? end. Elongates lagging strand until it reaches primer of preceding fragment. 3?*5? exonuclease activity "proofreads" each added nucleotide. DNA polymerase ill has 5?*3? synthesis and proofreads with 3?*5? exonuclease.7DNA polymerase IProkaryotic only. Degrades RNA primer; replaces it with DNA. Has same functions as DNA polymerase III but also excises RNA primer with 5?*3? exonuclease.10DNA ligaseCatalyzes the formation of a phosphodiester bond within a strand of double- stranded DNA (i.e., joins Okazaki fragments). Thus, Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand.11TelomeraseAn RNA-dependent DNA polymerase that adds DNA to 3? ends of chromosomes to avoid loss of genetic material with every duplication.
Helicase
Topoisomerase
DNA Ligase
DNA primase
Molecular Genetics