Question

1. Explain how the nurturing behavior of a mother during the first week of life can shape her child's ability to respond to stress. Draw it and label relevant genes/proteins.​

2. Compare and contrast maintenance methylation vs De Novo Methylation, including enzymes involved and cellular functions.​

3. Explain the mechanism of DNA methylation, including what DNA residue is modified, by what enzymes, and the impact on gene expression and chromatin state. Draw it!​

Answer 1

1. Breastfed babies feed more often than do formula-fed babies who are also more likely to be fed on schedule. Also, because breastfed babies feed more often, they tend to be touched, held, and interacted with more.

Breastfed babies are more likely to sleep all or part of the night in the same bed with mother, a healthy parenting practice that further increases daily "touch-time". Touch – and the lack of it – has a powerful influence on a child’s physical and intellectual development. Breastfeeding mothers may also be more sensitive to their child’s signals; to be successful at breastfeeding a mother must watch her baby rather than the clock or the marks on the feeding bottle.

2.DNMT1 is the proposed maintenancemethyltransferase that is responsible for copying DNA methylation patterns to the daughter strands during DNA replication.

*(DNA (cytosine-5)-methyltransferase 1)

Vs

DNMT3a and DNMT3b are the de novo methyltransferases that set up DNAmethylation patterns early in development.

*(DNA (cytosine-5)-methyltransferase 3A/3B)

3. DNA methylation is a process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription. DNA methylation is essential for normal development and is associated with a number of key processes including genomic imprinting, X-chromosome inactivation, repression of transposable elements, aging and carcinogenesis. Two of DNA's four bases, cytosine and adenine, can be methylated. Cytosine methylation is widespread in both eukaryotes and prokaryotes. Adenine methylation has been observed in bacterial, plant and recently in mammalian DNA.