Dna methylation

Definition

DNA methylation is a biochemical process that involves the addition of a methyl group to the DNA molecule, typically at the cytosine base in a CpG dinucleotide context. This modification can influence gene expression by altering the accessibility of DNA to transcription factors and the transcription machinery, thus playing a critical role in regulating gene activity at the transcriptional level.

5 Must Know Facts For Your Next Test

1. DNA methylation is generally associated with gene repression, meaning that heavily methylated regions of DNA are often not actively transcribed.
2. This process is crucial for normal development and cellular differentiation, allowing cells to adopt specific functions by turning genes on or off.
3. DNA methylation patterns can be inherited from one generation to another, contributing to the field of epigenetics and influencing traits without altering the DNA sequence.
4. Abnormal DNA methylation has been linked to various diseases, including cancer, where tumor suppressor genes may be silenced through hypermethylation.
5. Environmental factors, such as diet and exposure to toxins, can influence DNA methylation patterns, demonstrating how lifestyle choices can affect gene regulation.

Review Questions

• How does DNA methylation influence gene expression and what role does it play in cellular differentiation?
  • DNA methylation influences gene expression primarily by repressing gene activity when methyl groups are added to the cytosine bases in promoter regions. This prevents transcription factors from accessing the DNA and initiating the transcription process. In cellular differentiation, specific genes are turned on or off through unique patterns of DNA methylation, allowing cells to develop into distinct types with specialized functions.
• What are the potential consequences of abnormal DNA methylation patterns in human health, particularly regarding cancer?
  • Abnormal DNA methylation patterns can lead to significant health issues, especially in cancer development. Hypermethylation of tumor suppressor genes can silence their expression, preventing them from carrying out their protective roles against tumor formation. This loss of function can contribute to uncontrolled cell growth and proliferation, characteristic of cancerous cells. Furthermore, hypomethylation may activate oncogenes, further promoting malignancy.
• Evaluate the impact of environmental factors on DNA methylation and how this relates to epigenetic inheritance.
  • Environmental factors such as diet, toxins, and stress can significantly impact DNA methylation patterns by adding or removing methyl groups from DNA. These changes can affect gene expression in an individual and may also be passed down to future generations, illustrating the concept of epigenetic inheritance. This means that an individual's lifestyle choices or environmental exposures can alter their offspring's genetic regulation without changing the underlying DNA sequence, thus influencing traits and disease susceptibility across generations.

Related terms

Histone modification: The chemical alteration of histone proteins, such as acetylation or phosphorylation, that can impact gene expression by influencing chromatin structure and accessibility.

Epigenetics: The study of heritable changes in gene expression that do not involve changes to the underlying DNA sequence, including mechanisms like DNA methylation and histone modification.

Transcription factors: Proteins that bind to specific DNA sequences to regulate the transcription of genetic information from DNA to mRNA, often influenced by epigenetic modifications like DNA methylation.