DNA Polymerase is an enzyme that allows new cells in the body to be created and strands of DNA to be duplicated. These enzymes store information from a cell as the divides, allowing the new cell to contain the same information. When the enzymes duplicate information from the original cell before cell division, it is called polymerization. Additionally, DNA Polymerase are useful when duplicating DNA. These enzymes can use strands of DNA as a guide, or template, and assist in creating a duplicate strand. The enzymes are also useful in cell repair. With the ability to assist in cell reproduction, these enzymes can also help prevent the death of cells.
When replicating DNA, DNA Polymerases add nucleotides to a part of the DNA strand that match the guide, or template, strand. The original DNA strand creates a replication fork, which allows the DNA Polymerase to do the job of synthesizing new DNA. Essentially using a piece of one strand of DNA to make another, much like a copy machine would for a document, in a way. In order for this DNA replication to occur, there has to be a strand of DNA that creates a replication fork. Without the replication fork, nothing can happen, because the DNA strand cannot be created from scratch.
Some DNA Polymerases can correct DNA errors. When building a new strand, there are some of these enzymes with an ability known as proofreading. Proofreading allows the DNA Polymerase to recognize and error, remove it, and replace it. The result is an error-free strand of DNA. Not all of the enzymes possess this ability. Since it is only possible for these enzymes to use existing strands of DNA as a guide or template, error correction only works with mistakes. In other words, it is not possible to make something different in the replication than it is in the original.
There are seven family subclasses of DNA Polymerase. Some of these subclasses have been thoroughly studied, such as Family Subclass I. In this subclass there are a number of bacteria polymerase, and it includes both replicative and repair DNA Polymerases. Other subclasses have not been studied a great deal, so more exploration is required to garner knowledge. An example is Family Subclass IV, of which little is known. There is even a subclass-Family Subclass VII-that uses RNA as a guide, or template, for replicating strands of DNA.
DNA Polymerases, in effect, make reproduction possible. Because of their ability replicate strands of DNA and even correct errors, biological traits are passed from parents to children. It is DNA Polymerase that makes a child of two brown-eyes parents have brown eyes. Many children resemble their parents in one way or another, and that is because of their DNA, of which part is a replication of a parent's DNA. Reproduction, as we know it, would be very different if it were not for these little enzymes. The enzymes take DNA information from two parents, and replicate it for their offspring.
Klenow (3′→ 5′ exo-) is a mesophilic DNA polymerase deficient in both proofreading (3′→ 5′) and nick-translation (5′→ 3′) nuclease activities, and that displays a moderate strand displacement activity during DNA synthesis. The protein is expressed as a truncated product of the E.coli PolA gene and contains the D355A and E357A mutations.
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