Dna Errors In Replication

DNA replication usually occurs with great accuracy. Only about one error occurs for every billion paired nucleotides added. That's the equivalent of typing this book 1,000 times and making only one typing error. What accounts for this accuracy? DNA polymerases have repair functions that "proofread" DNA in the same way a friend might check a term paper for spelling errors. For example, if an adenine pairs with a cytosine instead of a thymine, DNA polymerase can repair the error by removing the mispaired cytosine and replacing it with a thymine.

When mistakes in DNA replication do occur, the base sequence of the newly formed DNA differs from the base sequence of the original DNA. A change in the nucleotide sequence of a DNA molecule is called a mutation. Mutations can have serious effects on the function of an important gene and disrupt an important cell function.

Some errors escape repair. In addition, chemicals and ultraviolet radiation from the sun can damage DNA. Some mutations can lead to cancer, such as the one shown in Figure 10-11. Thus, an effective mechanism for the repair of damaged DNA is very important to the survival of an organism.

DNA Replication and Cancer

DNA replication is an elegant process in which genetic information is passed from cell to cell for thousands of generations. It also explains how mutations can arise and lead to altered cells and organisms. Sometimes, the changes allow individuals to survive and reproduce better, so these variations increase in the population over many generations. Sometimes, mutations that are not repaired can cause diseases such as cancer. For example, mutations that affect genes that control how a cell divides can lead to an abnormal mass of cells called a tumor. Studying DNA replication is one promising avenue to understanding and treating various types of human cancers.

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

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