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18 Cards in this Set
- Front
- Back
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the cell is not yet visibly differentiated, but its fate has become restricted
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Commitment
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A cell could continue to become differentiated in a neutral environment with out further outside influence.
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Specification
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the cell will become differentiated in any environment in which it can survive.
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Determination
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If an addition that donation or substitution experiment upon an embryo produces abnormal development
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Mosaic, Autonomous
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what a cell will become in the normal course of development.
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Fate
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the full list of everything that a cell might possibly become in the most exceptional circumstances
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Potency
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potency=fate
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mosaic development
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If in addition, deletion or substitution experiment to an embryo produces an harmonious whole In this case, potency is greater than fate.
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Regulative Development (Conditional specification)
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What a cell becomes depends upon its position in the embryo
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Regulative
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We might say that its neighbors, tell it how to develop. Or, we might say that it somehow learns its position and then selects an appropriate program of development from its genetic repertoire.
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Regulative
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: “magic cookie” in cytoplasm; “tells” cell what to become
(“tells” nucleus what to make). |
Autonomous
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: neighboring cells give the cell “magic cookies”
that “tell” it what to become. (Positional Information) |
Conditional
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nucleus migrates to cytoplasm containing “magic cookies”
that “tell” it what to become |
Syncytial
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: patch of cells that will regulate in response to addition or deletion or substitution
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Developmental Field
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properties of each cell build the regulation field
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Turing Hypothesis
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special boundary properties (source and sink) are required; plus a mechanism for spontaneity
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Wolpert Hypothesis
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if you switch American cells (stripes) into French flag, they will learn their new position (upper left hand corner) and select correct program from their American genome (they select stars, correct for upper left hand corner.
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Substitution
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Polarity (Source & Sink)
Gradient (diffusible, chemical signal; morphogen) Threshold Spontaneity (Source & Sink regenerate) A cell “learns its position, then selects and appropriate program of development from its genome." |
Wolpert’s theory of Positional Information
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