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DNA Replication. An Overview of the Process. Defined…. DNA Replication Prior to dividing, a cell will replicate its DNA to ensure that each new cell has a complete set of DNA molecules. Defined…. DNA Replication

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Dna replication

DNA Replication

An Overview of the Process


  • DNA Replication

    • Prior to dividing, a cell will replicate its DNA to ensure that each new cell has a complete set of DNA molecules


  • DNA Replication

    • This is when the double helix is separated into 2 separate “template” strands by an enzyme called helicase, so that an enzyme called DNA polymerase can pair free floating bases to the “template” strand forming a new “complimentary” strand, thus duplicating the existing supply of DNA molecules


As usual
As usual…

  • Let’s take this one step at a time:

    • When and where does this happen?

    • How are the 2 sides of DNA separated?

    • How is the new DNA made?

The background info
The Background Info:

  • Remember:

    • DNA is the molecule that is made of phosphate groups, deoxyribose sugar groups, and nitrogenous bases organized in a long, double helix shape, and stores our genetic information

    • In other words, our genes are in our DNA

The background info1
The Background Info:

  • Remember:

    • The cell cycle consists of a series of steps:

      • Interphase

        • G1: cell growth

        • S: Chromosome replication/DNA synthesis

        • G2: organelles essential to division are made

      • M Phase

        • Mitosis

          • Prophase

          • Metaphase

          • Anaphase

          • Telophase

        • Cell Division

          • Cytokinesis

When and where
When and Where?

  • Now that we remember that, let’s put it together with what we’re learning about DNA replication…

  • DNA is separated into 2 halves (called 2 separate “strands”) and replicated during the synthesis stage of the cell cycle (called S phase)

  • This occurs while DNA is in the cell’s nucleus

How is dna separated
How is DNA Separated?

  • The 2 sides of the DNA molecule are separated into 2 separate “strands” by an enzyme called helicase

Key info
Key Info:

  • An enzyme called helicase?

    • Back up: an enzyme is a protein that acts as a biological catalyst

    • Back up further: a catalyst is a substance that speeds up the rate of a chemical reaction

    • Put it together: helicase is a substance made of protein that acts during the process of DNA replication

How is dna separated1
How is DNA Separated?

  • As you can see, helicase “unzips” or “unwinds” the double helix of DNA into 2 separate strands by breaking hydrogen bonds between bases

  • You are left with 2 template strands

    • A template strand is a strand of DNA that you can use to build another matching strand, thus making more DNA

replication bubble

How is new dna made
How is New DNA Made?

  • With the 2 template strands separated, we can see how new DNA is made:

  • Another enzyme called DNA Polymerase attaches free floating bases to the template strands following the rules of base pairing

    • (A with T, G with C)

  • Take a look…

How is new dna made2
How is New DNA Made?

  • Better yet, watch this youtube clip!