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Lecture 15

Biology 1002B Lecture Notes - Lecture 15: Mutation, Chromatin, Nucleosome


Department
Biology
Course Code
BIOL 1002B
Professor
Tom Haffie
Lecture
15

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Lecture 15: Identical Twins or Not
Monday, March 04, 2013
10:25 AM
Today's Topics:
Identical twins or not
Announcements:
Homework:
Lecture Topic:
Xist (X inactive specific transcript) RNA binds along the inactive X chromosomes, silencing
most genes
The genes become in inaccessible to transcription machinery by Xist RNA coating the
chromosomes and making them inactive (stable throughout the life)
This is an epigenetic mechanism
What is different about identical twins?
Make different gametes
Different gene expression
Mutation
Random X chromosome inactivation creates genetic mosaics in females
All of the decedents of the original cell, maintain the same X-chromosome inactivation
(maternal/paternal)
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