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27 Cards in this Set
- Front
- Back
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what is organogensis
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development of body structures |
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what is the hox gene
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-used throughout the animal kingdom |
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what are the four classes of hox genes
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what are the subclasses of the hox genes |
B- 1-9 C - 1-13 D - 1-13 |
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hox genes are expressed by the
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neural tube |
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when does organogenesis start
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after neurulation is complete |
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how are hox genes expression organized along the neural tube? what number subclass is located where
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-low number subclasses are anterior -high numbers are posterior |
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how do hox genes coordinate development
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-subclass 3 - anterior, cervical vertebrate of the neck -subclass 7 - thoracic vertebrate -subclass 10 - lumbar vertebrate |
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what hox genes coordinate the structures in your head
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1,2,3 etc. |
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what hox genes coordinate development of thoracic structures
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6,7,8
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what hox genes coordinate development of abdomen |
10 |
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how does retinoic acid affect hox gene expression
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called the NODE -concentration of retinoic acid affects what hox genes will be on/off -high concentration = low numbers are on -low concentration = high numbers are non |
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what is the organizer at the anterior end of the neural tube called and what does it secrete |
called the node and secretes retinoic acid |
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what experiments have proven than retinoic concentrations are important for hox gene on/off?
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inject retinoic acid = can change the expression of hox genes along the neural tube |
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how are hox genes expressed in limbs?
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along three axes along the limb (arm/leg) |
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hy are the limbs so similar in different animals
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because they are all controlled by hox genes
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development of limbs
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-area of first thoracic vertebrae -retinoic acid controls whether it's on/off - its location |
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where does the response/growth of limb bud start? |
-starts as a result of growth factor - fibroblast growth factor, specific for connective tissue -mesoderm proliferates in response to FGF - differentiate into skeletal precursor cells and muscle (somites) |
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what is the apical ectodermal ridge
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as the mesoderm is developing due to FGF the ectoderm also differentiates - at the tip of the limb bud is the apical ectodermal ridge which acts as the signaling center -directs the patterning of limbs along the three different axes |
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what are the three axes that the limb develops along
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-anterior to posterior (thumb to pinkie) -proximal to distal |
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what causes the hox genes to turn on/off in the limb bud
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-NOT DUE to retinoic acid concentration at this point -but hox genes are responsible |
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what is the progress zone
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-the progress zone stays near the trunk the first cells that leave the progress zone are the edge (fingers) the cells last to leave will be nearest to the trunk |
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what genes control the anterior posterior axis of limbs? what genes control the dorsal/ventral axis of limbs? |
-dorsal-ventral - Wnt signaling |
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how are your fingers made
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via apoptosis - programmed cell death |
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what is the interdigit necrotic zone
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-accomplished by BMP - bone morphogenetic protein |
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what is bone morphogenic protein |
in the interdigit necrotic zone - directs cell death/apoptosis |
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how do cells in the limb prevent being apoptosed
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cells around bone produce noggin prevent apoptosis from happening |
