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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 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 • 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 …whoa
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: • 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 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? • 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? • The 2 sides of the DNA molecule are separated into 2 separate “strands” by an enzyme called helicase
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 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? • 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 Made? • Better yet, watch this youtube clip!