Maternal imprinting

Definition

Maternal imprinting is a form of genomic imprinting where genes inherited from the mother are expressed while the paternal alleles are silenced. This selective gene expression can influence various biological processes, including growth and development, and is crucial in understanding genetic disorders that arise from imprinting errors.

5 Must Know Facts For Your Next Test

1. Maternal imprinting is essential for proper fetal growth, as it ensures that certain genes necessary for development are expressed only from the maternal side.
2. Errors in maternal imprinting can lead to various genetic disorders, highlighting the importance of precise gene regulation during development.
3. The mechanisms behind maternal imprinting involve DNA methylation and histone modifications, which help to silence the paternal allele.
4. Maternal imprinting can have significant evolutionary implications, influencing parental investment strategies and offspring survival.
5. Certain imprinted genes may also play roles in cancer biology, as their dysregulation can lead to uncontrolled cell growth.

Review Questions

• What are the primary mechanisms involved in maternal imprinting and how do they function to silence paternal alleles?
  • The primary mechanisms involved in maternal imprinting include DNA methylation and histone modifications. DNA methylation adds methyl groups to specific cytosine residues in the DNA sequence, which can inhibit gene transcription. Histone modifications alter the structure of chromatin, making it either more or less accessible for transcription factors. Together, these processes effectively silence the paternal allele while allowing for expression of the maternal allele.
• Discuss how errors in maternal imprinting can lead to genetic disorders and provide an example of such a disorder.
  • Errors in maternal imprinting can disrupt the normal expression patterns of imprinted genes, potentially leading to developmental and health issues. One notable example is Prader-Willi Syndrome, which arises when the paternal allele in a specific region of chromosome 15 is deleted or not expressed. In this case, the lack of expression of normally active paternal genes due to improper imprinting leads to symptoms such as hypotonia, obesity, and cognitive challenges.
• Evaluate the evolutionary significance of maternal imprinting in terms of its impact on parental investment and offspring survival.
  • Maternal imprinting has considerable evolutionary significance as it influences how resources are allocated to offspring by parents. The genes that exhibit maternal imprinting often promote growth and resource acquisition, potentially leading to offspring that are better adapted for survival. This selective pressure encourages mothers to invest more heavily in their offspring that express these critical maternal alleles, thereby enhancing reproductive success and ensuring that favorable traits are passed on through generations.

Related terms

Genomic Imprinting: A genetic phenomenon where certain genes are expressed in a parent-of-origin-specific manner, meaning that either the maternal or paternal allele is epigenetically silenced.

Epigenetics: The study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence, often influenced by environmental factors.

Prader-Willi Syndrome: A genetic disorder caused by the loss of function of genes in a specific region of chromosome 15, which can result from the absence of paternal allele expression due to genomic imprinting.