DNA polymerase

Definition

DNA polymerase is an essential enzyme responsible for synthesizing new strands of DNA by adding nucleotides to a growing DNA chain during DNA replication. It plays a critical role in ensuring the accuracy and fidelity of DNA replication, which is fundamental to cell division, gene expression, and the overall maintenance of genetic information.

5 Must Know Facts For Your Next Test

1. DNA polymerase requires a primer to initiate the synthesis of a new DNA strand, as it cannot start from scratch.
2. There are several types of DNA polymerases, each with specific functions such as synthesizing new strands or proofreading existing ones to correct errors.
3. During DNA replication, DNA polymerase works in the 5' to 3' direction, meaning it adds nucleotides to the growing strand at the 3' end.
4. The enzyme also has exonuclease activity, allowing it to remove incorrectly paired nucleotides to enhance the fidelity of DNA replication.
5. DNA polymerase plays a crucial role in cellular processes beyond replication, such as DNA repair and recombination.

Review Questions

• Explain how DNA polymerase contributes to the accuracy of DNA replication.
  • DNA polymerase enhances the accuracy of DNA replication through its proofreading ability. After adding a nucleotide, it checks whether the base pair is correctly matched with the template strand. If an incorrect nucleotide is incorporated, the enzyme can use its exonuclease activity to remove it and replace it with the correct one. This ensures that genetic information is accurately copied, minimizing mutations.
• Discuss the differences in function between various types of DNA polymerases in eukaryotic cells.
  • Eukaryotic cells have multiple types of DNA polymerases that perform different roles during replication and repair. For instance, DNA polymerase alpha is involved in initiating DNA synthesis by working with primase, while DNA polymerase delta synthesizes the lagging strand and has strong proofreading capabilities. On the other hand, DNA polymerase epsilon primarily synthesizes the leading strand. Each type is specialized for its task, ensuring efficient and accurate replication and maintenance of the genome.
• Evaluate the implications of malfunctioning DNA polymerase on genomic stability and its potential role in disease development.
  • Malfunctioning DNA polymerase can lead to increased mutation rates due to errors during DNA replication not being corrected. This lack of fidelity can compromise genomic stability and contribute to various diseases, including cancer. For example, if a mutation occurs in a gene regulating cell division due to faulty proofreading by DNA polymerase, it could result in uncontrolled cell growth. Understanding these implications underscores the importance of this enzyme in both basic biological processes and disease mechanisms.

Related terms

Nucleotide: The basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Helicase: An enzyme that unwinds the double-stranded DNA helix during replication, allowing DNA polymerase to access the template strands.

Okazaki fragments:

Short sequences of DNA that are synthesized discontinuously on the lagging strand during DNA replication, requiring multiple primers and processing by DNA polymerase.