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Introduction to DNA Replication quiz #1

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  • What is the primary function of topoisomerase in DNA replication?
    Topoisomerase relieves DNA supercoiling ahead of the replication fork.
  • What role does helicase play in DNA replication?
    Helicase unwinds the DNA double helix at the replication fork by breaking hydrogen bonds.
  • What is the function of single-stranded binding proteins (SSBs) during DNA replication?
    SSBs bind to and stabilize single-stranded DNA to prevent reannealing and degradation.
  • What is the purpose of RNA primers in DNA replication?
    RNA primers, created by primase, act as starting points for DNA synthesis.
  • Which enzyme is responsible for building new DNA strands in prokaryotes?
    DNA Polymerase III is the main enzyme responsible for building new DNA strands in prokaryotes.
  • What is the function of DNA Polymerase I in prokaryotic DNA replication?
    DNA Polymerase I replaces RNA primers with DNA.
  • What is the role of DNA ligase in DNA replication?
    DNA ligase covalently joins Okazaki fragments on the lagging strand.
  • Where does DNA replication begin in prokaryotic cells?
    DNA replication begins at a single origin of replication on the circular chromosome.
  • How many origins of replication do eukaryotic chromosomes typically have?
    Eukaryotic chromosomes have multiple origins of replication, sometimes up to 100 or more.
  • What is a replication fork?
    A replication fork is a Y-shaped region where DNA is unwound and replication occurs.
  • In which direction does DNA replication proceed at the replication fork?
    DNA replication proceeds bidirectionally at each replication fork.
  • What is the significance of the 5' to 3' direction in DNA synthesis?
    New DNA strands are always synthesized in the 5' to 3' direction.
  • What is DNA supercoiling and why must it be relieved during replication?
    DNA supercoiling is the over-twisting of DNA, which must be relieved to prevent inhibition of DNA replication.
  • What is the function of DNA gyrase in prokaryotes?
    DNA gyrase, a type of topoisomerase, relieves DNA supercoiling in prokaryotes.
  • What is the role of primase in DNA replication?
    Primase synthesizes RNA primers that provide a starting point for DNA polymerase.
  • after dna replication is completed, _____.
    two identical DNA molecules are formed, each consisting of one old (parental) strand and one newly synthesized strand, due to the semi-conservative nature of DNA replication.
  • dna is a self-replicating molecule. what accounts for this important property of dna?
    The self-replicating property of DNA is due to its double-stranded structure, where each strand serves as a template for the synthesis of a new complementary strand, facilitated by base pairing rules.
  • the action of helicase creates _____.
    The action of helicase creates single-stranded DNA by unwinding the double helix and breaking the hydrogen bonds between the two DNA strands.
  • What are the steps in DNA replication?
    Steps in DNA replication include initiation at the origin of replication, unwinding of DNA by helicase, stabilization of single strands by single-strand binding proteins, synthesis of RNA primers by primase, elongation of new DNA strands by DNA polymerase, and joining of Okazaki fragments by DNA ligase.
  • replication of chromosomal dna occurs __________.
    Replication of chromosomal DNA occurs bidirectionally from multiple origins of replication in eukaryotes and from a single origin in prokaryotes.
  • the first step in the replication of dna is catalyzed by _____.
    The first step in the replication of DNA is catalyzed by helicase, which unwinds the DNA double helix at the replication fork.