🐇honors biology review

key term - Dna methylation

Definition

DNA methylation is the process by which methyl groups are added to the DNA molecule, typically at the cytosine bases of cytosine-guanine (CpG) dinucleotides. This modification can affect gene expression without altering the underlying DNA sequence, playing a crucial role in regulating genes during development and cellular differentiation.

5 Must Know Facts For Your Next Test

  1. DNA methylation typically occurs at CpG sites, where a methyl group is added to the carbon 5 position of cytosine residues.
  2. In mammals, DNA methylation is essential for normal development and is involved in processes such as X-chromosome inactivation and genomic imprinting.
  3. Abnormal DNA methylation patterns can lead to various diseases, including cancer, where tumor suppressor genes may be silenced through hypermethylation.
  4. The addition or removal of methyl groups is mediated by enzymes called DNA methyltransferases and demethylases, respectively.
  5. Environmental factors such as diet, toxins, and stress can influence DNA methylation patterns, demonstrating the interaction between genetics and the environment.

Review Questions

  • How does DNA methylation influence gene expression during cellular differentiation?
    • DNA methylation influences gene expression by adding methyl groups to specific sites on the DNA, particularly at CpG dinucleotides. This modification can repress gene transcription by preventing the binding of transcription factors and other necessary proteins to the DNA. During cellular differentiation, specific patterns of DNA methylation help determine which genes are activated or silenced, ultimately guiding cells to develop into their specialized forms.
  • Discuss the role of enzymes in maintaining DNA methylation patterns and how this is relevant to gene regulation.
    • Enzymes known as DNA methyltransferases are responsible for adding methyl groups to cytosine residues, thus establishing DNA methylation patterns. Once established, these patterns can be maintained during cell division by maintenance methyltransferases, ensuring that daughter cells inherit the same methylation state. This process is crucial for gene regulation as it helps preserve tissue-specific gene expression profiles, allowing for proper function and identity of different cell types within an organism.
  • Evaluate how environmental factors can impact DNA methylation and consequently influence health outcomes.
    • Environmental factors such as diet, exposure to toxins, and lifestyle choices can significantly impact DNA methylation patterns. For instance, certain nutrients like folate are involved in the one-carbon metabolism pathway that affects methyl group availability for DNA methylation. Changes in these patterns can lead to misregulation of genes associated with diseases like cancer and metabolic disorders. Understanding this relationship underscores the importance of integrating environmental considerations into health strategies aimed at preventing epigenetic alterations.