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The Epigenetics of Identical Twins

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    Identical twins are genetic carbon copies
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    The DNA sequences of their genes are exactly the same
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    Yet physically, identical twins become increasingly different over time...
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    why is this so?
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    Genes provide the instructions
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    for the development and maintenance of the body.
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    Yet a second set of instructions known as the epigenome
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    interacts with DNA
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    to activate or suppress
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    the expression of particular genes.
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    Certain chemicals
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    known as epigenetic tags
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    turn genes OFF
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    or ON
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    without changing the underlying genetic code.
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    During fertilization
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    one set of chromosomes from Dad
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    and one set of chromosomes from Mum
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    are combined to form an embryo.
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    Epigenetic tags are erased
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    from Mum and Dad's chromosomes
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    during the first days after fertilization.
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    However, on some genes the tags remain
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    these are known as IMPRINTED genes.
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    Identical twins result
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    when a single embryo splits in two.
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    Each embryo has the same genome
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    and the same epigenome.
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    As the embryos develop
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    cells differentiate into distinct types
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    such as bone, muscle and skin.
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    As each type specialises epigenetic tags
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    activate and silence specific genes
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    leading the cells to specialise further.
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    Each cell type gradually takes on
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    a unique epigenetic profile.
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    Because the twins share the same environment
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    their epigenomes are very similar at birth
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    and through the early years of life.
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    As the twins age,
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    their environments begins to differ.
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    Their genomes remain the same
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    but signals from the environment
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    act on the twins epigenomes
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    to activate and silence
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    different genes.
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    Diet, for example
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    is an environmental factor
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    that can have an effect
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    on the epigenome.
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    Differences in physical activity
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    can also cause epigenetic differences
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    between the twins.
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    Exposure to toxins
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    can influence the epigenome.
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    Stress also plays a role
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    in shaping the epigenome.
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    By the time the twins
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    are well into adulhood
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    their epigenomes, thus gene expression patterns,
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    are very different...
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    ... making each twin unique!
Title:
The Epigenetics of Identical Twins
Description:

Why do the physical characteristics of identical twins diverge as they age? Follow the interaction of the environment and the genome in a pair of twins over time.

For other great videos, interactive activities and more, be sure to visit:
http://learn.genetics.utah.edu/content/epigenetics/

More information on how identical twins are helping scientists pinpoint environmental impact on the epigenome: http://learn.genetics.utah.edu/content/epigenetics/twins/

Teachers! Integrating the Epigenetics curriculum into your classroom is a breeze!
For activities, assessment questions, learning objectives, scientist talk videos,
background information and thoughts from other teachers, visit:
http://teach.genetics.utah.edu/content/epigenetics/
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Video Language:
English
Duration:
04:42

English subtitles

Revisions

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