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MDCAT
Biology
2009

Biology · Chromosomes and DNA

Work through this past-paper style MCQ, then read the full explanation. Practice more biology questions on mMCQ with adaptive drills and topic analytics.

Question

Enzyme which attaches the Okazaki fragments in lagging strand is called:

Options
  • A

    Restriction endonuclease

  • B

    DNA helicase

  • C

    Primase

  • D

    DNA ligase

Explanation

Explanation:

DNA Ligase is an enzyme that catalyzes the formation of a phosphodiester bond between adjacent Okazaki fragments on the lagging strand during DNA replication. This reaction joins the fragments together into a continuous strand. DNA Ligase is therefore essential for the completion of DNA replication on the lagging strand.

 Restriction endonuclease is an enzyme that cleaves DNA at specific sites called restriction sites. It is not involved in the attachment of Okazaki fragments during DNA replication.

 DNA helicase is an enzyme that unwinds the double-stranded DNA molecule at the replication fork during DNA replication. However, it is not involved in the attachment of Okazaki fragments during DNA replication.

Primase is an enzyme that synthesizes a short RNA primer on the DNA template strand during DNA replication. However, it is not involved in the attachment of Okazaki fragments during DNA replication.

Restriction endonuclease is an enzyme that cleaves DNA at specific sites called restriction sites. It is not involved in the attachment of Okazaki fragments during DNA replication.

DNA helicase is an enzyme that unwinds the double-stranded DNA molecule at the replication fork during DNA replication. However, it is not involved in the attachment of Okazaki fragments during DNA replication.

Primase is an enzyme that synthesizes a short RNA primer on the DNA template strand during DNA replication. However, it is not involved in the attachment of Okazaki fragments during DNA replication 

DNA Ligase is an enzyme that catalyzes the formation of a phosphodiester bond between adjacent Okazaki fragments on the lagging strand during DNA replication. This reaction joins the fragments together into a continuous strand. DNA Ligase is therefore essential for the completion of DNA replication on the lagging strand. 

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Tagged under Biology · Chromosomes and DNA · 2009