ANAT 2130 Lecture Notes - Lecture 8: Symmetry In Biology, Gastrointestinal Tract, Hox Gene
16 Oct 2016
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With repeating structural units: have ventral nervous systems. Insects: have six legs, four wings (diptera have two wings and two halteres) Example: insects have chemoreceptors on limbs and compound eyes. 2 eyes, 2 ears, 1 nose, taste receptors cranial. Tetrapod-pair of forelimbs and pair of hindlimb. Zygote: has all the required genetic information for formation of adult in its nucleus and cytoplasmic informational molecules. Cell division: produces trillions of cells from one. In both invertebrates and vertebrates, recent studies in molecular biology reveal some general principles. Eggs and early embryos have gradients morphogens, gene-derived proteins that simulate different nuclei in different parts of the embryo to different fates. Other genes produce protein transcription factors that drive determine segmentation, position of body parts, and types of cells formed. One tissue expresses a certain gene at a certain time and place, leading to synthesis of transcription factors.
