7d Nature vs nurture Flashcards
What is epigenetics?
Definition: Epigenetics is the study of heritable changes in gene expression that do not involve changes to the underlying DNA sequence. These changes can affect how genes are turned on or off.
Give two examples of how an environmental impact on genotype affects the phenotype.
Sun Exposure and Skin Color: Prolonged exposure to sunlight can increase melanin production, darkening the skin, regardless of genetic predisposition.
Nutrition and Height: A child’s growth can be stunted or enhanced by nutrition, even if the genetic potential for height is high or low.
What is DNA methylation?
Definition: DNA methylation is the addition of a methyl group to the DNA molecule, typically at the cytosine base of a CpG dinucleotide.
Function: It is a common epigenetic mechanism that can repress gene transcription when located in a gene promoter region.
What is histone modification?
Definition: Histone modification involves the addition or removal of chemical groups (such as acetyl, methyl, or phosphate groups) to histone proteins.
Function: These modifications can alter the structure of chromatin and thereby regulate gene expression by making DNA more or less accessible to the transcription machinery.
How do DNA methylation and histone modification impact phenotype?
Impact on Phenotype: Both DNA methylation and histone modification can alter gene expression without changing the DNA sequence. By turning genes on or off, or altering their level of activity, these epigenetic changes can influence an organism’s phenotype. For example:
DNA Methylation: Can silence tumor suppressor genes, leading to cancer development.
Histone Modification: Can activate genes involved in stress responses, altering behavior or physical traits in response to environmental factors.
