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DNA Replication

DNA Replication

Description:

This lesson will investigate the how and why the process of DNA replication occurs.

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Tutorial

What's Covered

This lesson will cover the role of DNA polymerase in:

  1. DNA Replication
  2. DNA Repair

1. DNA Replication

When a cell goes through cellular division and divides, it needs to be able to copy its DNA in order to pass on copies into new cells. This process is called DNA replication.

DNA molecules are copied so that traits can be passed from parents to offspring. DNA polymerase is an enzyme that assists in DNA replication. This enzyme unwinds a DNA molecule and then separates the DNA so that new DNA molecules can be produced using the old DNA molecules as a template.

Terms to Know

  • DNA Replication
  • The process of replicating DNA before a cell divides.
  • DNA Polymerases
  • An enzyme that assists in the process of DNA replication.

The first step is a DNA molecule before replication. It is made up of a phosphate sugar backbone, and the base pairs are still paired up inside of it.

REPLICATION (2).png

As the molecule moves into the second step, DNA polymerase will unwind and separate those DNA molecules. Then the old strands of DNA are used as a template in order to build new strands of DNA.

REPLICATION.png


The new bases pair up using the rules of base pairing creating a molecule that is half old and half new. These two strands will be identical to the original strand and each other.  This is called semiconservative replication and this is how DNA is replicated so that the traits can be passed from parents to offspring.

Term to Know

  • Semiconservative Replication
  • Half of a DNA molecule produced by DNA replication is "old" coming from the original strand of DNA and half is "new" and produced using the "old"

2. DNA Repair

DNA polymerase, in addition to playing a role in DNA replication also helps with DNA repair. Sometimes during the process of DNA replication DNA can change in a way that will change a gene, so a gene mutation can occur.

Term to Know

  • Gene Mutation
  • A change in the sequence of nucleotides in a gene.

A mutation is a change to a nucleotide sequence. There are various types of mutations, but one type is a base-pair substitution. A base-pair substitution is when the wrong nucleotide pairs with a base during replication. These mutations can occur and affect the way in which a gene is produced or functions.

ExampleIf thymine paired with guanine instead of adenine.

Term to Know

  • Base-Pair substitution
  • A type of gene mutation in which the wrong nucleotide is paired with a base during the process of DNA replication. The effects can range from none at all to life threatening.

Summary

DNA polymerase plays an important role in DNA Replication. It is the signal for DNA to unwind and separate. This allows new bases to come in a pair with the unwound strands. This is semiconservative replication because the strands are half old and half new. Two strands are created that are identical to the original. DNA polymerase also plays a role in DNA repair when mutations like base pair substitutions occur.

Source: This work is adapted from Sophia Author Amanda Soderlind

TERMS TO KNOW
  • DNA Replication

    The process of replicating DNA before a cell divides.

  • DNA Polymerases

    An enzyme that assists in the process of DNA replication.

  • Semiconservative Replication

    Half of a DNA molecule produced by DNA replication is "old" coming from the original strand of DNA and half is "new" and produced using the "old" strand as a template.

  • Gene Mutation

    A change in the sequence of nucleotides in a gene.

  • Base-Pair substitution

    A type of gene mutation in which the wrong nucleotide is paired with a base during the process of DNA replication. The effects can range from none at all to life threatening.