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DEVELOPMENT QUESTION 1988: L. PETERSON/AP BIOLOGY Discuss the processes of cleavage, gastrulation, and neurulation in the frog embryo; tell what each process accomplishes. Describe an experiment that illustrates the importance of induction in development. STANDARDS: 1 point for each major item under each major heading CLEAVAGE (max. 3 points) __Mitotic or cell division, or increase in cell number __No cellular growth __Holoblastic (complete division) __Unequal __Radial (Indeterminant) __Involves use of maternal RNA __1st vertical [1 point for directionality of early cleavage divisions] __2nd vertical, perpendicular to 1st __3rd horizontal, perpendicular to 1st and 2nd, unequal __Grey crescent establishes planes of cleavage __Divisions more rapid at animal pole (max. 2 points) Accomplishes __Forms blastula or hollow ball of cells __Forms blastocoel __Forms blastomeres (micromeres, macromeres) __Forms or increases DNA in embryo __Produces unequal distribution of cytoplasmic contents in blastomeres (max. 2 points) NEURULATION (max. 3 points) __Epidermal thickening, flattening in dorsal midline (neural plate formation) __Plate develops longitudinal depression (neural groove, neural folds) __Neural folds fuse __Neural tube pinches free of epidermis, sinks inward __Notochord (chordamesoderm) required for neurulation (max. 2 points) Accomplishes __Forms neural tube (CNS, nerve cord, spinal cord, brain, nervous system) __Forms neurula __Forms neural crests (max. 2 points)
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This note was uploaded on 10/30/2009 for the course SI 0126 taught by Professor Gourney during the Summer '09 term at École Normale Supérieure.

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