Dna methylation

Definition

DNA methylation is a biochemical process involving the addition of a methyl group to the DNA molecule, typically at the cytosine base in a CpG dinucleotide. This modification plays a crucial role in regulating gene expression and can influence various cellular processes. It interacts closely with other epigenetic marks and is essential for maintaining genome stability, impacting how genes are turned on or off without altering the underlying DNA sequence.

5 Must Know Facts For Your Next Test

1. DNA methylation is primarily associated with gene silencing, where methyl groups prevent transcription factors from binding to DNA, effectively turning off gene expression.
2. The addition of methyl groups occurs through the action of enzymes known as DNA methyltransferases, which transfer a methyl group from S-adenosyl methionine (SAM) to cytosine bases.
3. Aberrant DNA methylation patterns are linked to various diseases, including cancer, where hypermethylation can lead to tumor suppressor gene silencing.
4. DNA methylation is a reversible modification, meaning it can be added or removed, allowing for dynamic regulation of gene expression in response to environmental factors.
5. In addition to influencing gene expression, DNA methylation plays a role in genomic imprinting, where certain genes are expressed in a parent-of-origin-specific manner.

Review Questions

• How does DNA methylation affect gene expression and what implications does this have for cellular function?
  • DNA methylation typically silences gene expression by preventing transcription factors from accessing the promoter regions of genes. This mechanism is crucial for normal cellular function as it allows cells to regulate which genes are active at any given time. For instance, in differentiated cells, specific genes need to be turned off to maintain their identity and function, showing how methylation serves as a key control point in cellular processes.
• Discuss the relationship between DNA methylation and other epigenetic modifications in regulating genome stability.
  • DNA methylation works in conjunction with other epigenetic modifications such as histone modifications to maintain genome stability and regulate gene expression. While DNA methylation primarily silences genes, histone modifications can either enhance or repress transcription based on their chemical nature. Together, these modifications form an intricate regulatory network that ensures proper chromatin structure and function, ultimately contributing to cellular identity and response to environmental changes.
• Evaluate the potential consequences of disrupted DNA methylation patterns in human health and disease.
  • Disrupted DNA methylation patterns can lead to significant health issues, most notably cancer. For example, hypermethylation of tumor suppressor genes can result in their silencing, allowing for uncontrolled cell growth. Conversely, global hypomethylation may activate oncogenes or transposable elements, further contributing to genomic instability. Understanding these alterations provides insight into disease mechanisms and may inform therapeutic strategies targeting epigenetic modifications for treatment.

Related terms

Histone Modification: Chemical changes to the proteins called histones that help package DNA in a way that can regulate gene expression.

Epigenetics:

The study of heritable changes in gene expression that do not involve changes to the underlying DNA sequence.

Transcription Factors:

Proteins that bind to specific DNA sequences, playing a key role in regulating the transcription of genetic information from DNA to messenger RNA.