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NOVA scienceNOW: Epigenetics

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Scientists introduce epigenetics, the study of mechanisms controlling gene expression that are independent of the DNA sequence itself. Researchers examine the role epigenetic factors might play in cell differentiation, cell development, disease, and heredity.

This NOVA scienceNOW segment:

  • introduces epigenetics and notes a key difference between genetics and epigenetics. Genetics is the study of DNA-based inherited characteristics in organisms while epigenetics can involve modifications to DNA (i.e., DNA methylation) or changes to the structures surrounding the DNA (i.e., the chromatin's histones).

  • details one epigenetic mechanism by which methyl groups attach to the histones, affecting the expression of the DNA's genetic code.

  • explains that chemicals that may have an epigenetic effect, such as methyl groups, can enter the body from one's environment. Consequently, an individual's choices and personal history, such as diet and smoking, can influence his or her exposure to epigenetic triggers and their accumulation in the body.

  • describes studies that demonstrate the effect of epigenetic factors. For example, one set of genetically identical mice was fed food rich in methyl groups. The methyl groups bonded to the mice's chromatin and blocked the expression of certain genes. This epigenetic effect produced two sets of mice that looked extremely different.

  • reports on studies of identical (human) twins that reveal a measurable accumulation of epigenetic changes as the twins age.

  • notes the development of a promising line of therapies that work by rearranging a cell's epigenetic tags. One epigenetic therapy mentioned attempts to alter the behavior of cancer cells.

Taping Rights: Can be used up to one year after the program is taped off the air.

Teacher's Guide
NOVA scienceNOW: Epigenetics
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