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| Unit 3: Demos |
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Operon Tutorial (optional, but helpful!) Positive v. negative control of prokaryotic gene transcription Transcription of eukaryotic vs. prokaryotic genomes (6c) How Does Methylation Control Synthesis of Proteins? optional: Human
clone produces stem cells ... Or
not? Evidence found that data were fraudulent Yolk content and cleavage in human eggs (15c) Notochord
development (17a) Comparative development (18b) Determinate v. indeterminate cleavage & embryonic induction Unit 3 Slides (accompanying text can be found in your Survival Manual on pages 59-61.) |
Notochord Development The notochord is one of the defining characteristics of the phylum Chordata and serves as a internal support structure for the body, preventing telescoping of the body when lateral muscles contract. Present at some stage of development in all chordates, the notochord's role is taken over by the vertebral column in the adults of many vertebrate groups. Note that the notochord develops from the band of dorsally-positioned mesoderm that initially flows into the developing embryo during the early stages of gastrulation. The mesoderm that forms the notochord is called chordamesoderm and is important not only in forming the notochord itself but also in inducing development of the overlying ectoderm into the neural tube (see Figure 12.20 at bottom of page).
Figure 4.13 from K. Kalthoff. 2001. Analysis of Biological Development. McGraw Hill, Boston.
Figure 2.5 from K.V. Kardong. 2002. Vertebrates - Comparative Anatomy, Function, Evolution, 3rd edition. McGraw Hill, Boston.
Figure 12.20 from K. Kalthoff. 2001. Analysis of Biological Development. McGraw Hill, Boston. Experiments like the one shown in Figure 12.20 (above) demonstrated that the chordamesoderm (the tissue that initially forms the dorsal lip of the blastopore and then moves into the embryo later in gastrulation) is important in inducing the proper development of the overlying ectodermal tissue into the neural tube. |
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