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Delve into the world of epigenetics in twins to uncover how factors beyond genetics influence genetic makeup and phenotype variations. Learn about histone modifications and DNA methylation as mechanisms for gene expression regulation.
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Epigenetics Honors Biology
What is Epigenetics? • Epi = “on top of” • Genetics = genetic make up of an organism • Epigenetics… what factors, on top of genes, impact our genetic make up
Same genes, different phenotypes • A Tale of Two Mice – part I
What does it mean to say that two individuals are genetically identical? • How can two genetically identical mice look so different?
Condensed • Chromatin Hydrogen Bonds (between bases) Decondensed Chromatin Nucleotide (consists of a base, a 5-carbon sugar, and a phosphate group) Phosphodiester Bond (between adjacent nucleotides)
What is Epigenetics? • Refers to changes in gene expression caused by mechanisms other than changes in the underlying DNA sequence • Enables a cell/organism to respond to its dynamic external environment during development and throughout life! • Epigenetic changes to the genome can be inherited if these changes occur in cells giving rise to gametes
Two Epigenetic Mechanisms Histone Modifications DNA Methylation Video
1. Histone modification • If the way that DNA is wrapped around the histones changes, gene expression can change (transcription)
2. DNA methylation • The addition of methyl groups to DNA can also change gene expression (transcription)
A Tale of Two Mice – part II • Complete Step 3 on Student Worksheet
A Tale of Two Mice – parts III-V • Finish Steps 4-5 on Student Worksheet