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Regulating Gene Expression. Reviewing Vocab …. GENE : a segment of DNA that codes for a particular protein/trait An expressed gene is one that is being transcribed (i.e. it is turned to the “on” position and is being used to make proteins !)
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Reviewing Vocab… • GENE: a segment of DNA that codes for a particular protein/trait • An expressed gene is one that is being transcribed (i.e. it is turned to the “on” position and is being used to make proteins!) • A repressed gene is one that is not being transcribed (i.e. it is turned to the “off” position)
Demonstration • Observe the two DNA models – can you identify the histones? • What is different about the two models?
Video • http://learn.genetics.utah.edu/content/epigenetics/intro/
Vocabulary • Epigenome • Epigenetic Tags • What do these do to the physical structure of DNA? • What kinds of things shape your epigenome?
DNA structure and Regulation • http://learn.genetics.utah.edu/content/epigenetics/control/ • Watch what happens to the appearance of the DNA, the # of mRNA, # of proteins, and the appearance of the cell as you turn the knob.
True or False? Methyl and acetyl groups control gene expression by controlling access to DNA.
Lick your rats • http://learn.genetics.utah.edu/content/epigenetics/rats/
So what does this have to do with protein synthesis? • http://www.teachersdomain.org/asset/biot09_vid_epigenetics/ • http://www.pbs.org/wgbh/nova/teachers/body/epigenetics.html • http://www.pbs.org/wgbh/nova/body/epigenetics.html
30,000+ genes • Does each cell need to be using all 30,000 genes? (hint: cell specialization!) • Do you need to be using all 30,000 genes at all times? (hint: energy conservation!)
Regulation • “Controls” over gene expression • Variety of methods • One basic way is by modifying the structure of DNA
Epigenetics • http://learn.genetics.utah.edu/content/epigenetics/intro/
Epigenetics The development and maintenance of an organism is orchestrated by a set of chemical reactions that switch parts of the genome off and on at strategic times and locations. • Epigenetics is the study of these reactions and the factors that influence them.
For example… • Genes that control whether or not a cell gets to go through mitosis… • regularly turned on and off = cells only divide when needed. • Cancer cells = unregulated cell division = epigenetic profile looks different…
Epigenetic Tags • Acetyl and methyl groups • Chemicals that act as switches that determine gene expression without changing the underlying genetic code • Turn genes on or off in response to cell signals • Create a layer of control called the epigenome
Epigenome • Reacts to factors throughout your lifetime. • Can affect future generations too…
Regulation of Genes • Genes can be turned on or off • Off = not active, not making proteins • Tightly wound • DNA covered in methyl groups • On = active, making proteins • Not tightly wound • Acetyl groups attached to histones
Other ways to control gene expression… • Intronsvsexons • Activity -