lecture_18__2009

lecture_18__2009 - Distinguished Alumni Panel 2 pm Friday...

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Distinguished Alumni Panel 2 pm, Friday, Oct. 16, Newton 204 Come and hear from a variety of successful biology graduates;     find out their keys to success, both at Geneseo and beyond. Refreshments follow.
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Lecture 18, 10-16-09 Finishing up Chapter 47, Animal Development and then on to Chapter 48
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Which of the following statements is false. A. Non-avian reptiles show holoblastic cleavage A. The acrosomal reaction occurs before the cortical reaction B. The binding of the sperm to the egg triggers membrane depolarization in the egg C. Avian-reptiles show meroblastic cleavage D. Mesoderm gives rise to both the notochord
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E. Developmental Adaptations of Amniotes The embryos of avian reptiles, non-avian reptiles, and mammals develop within a fluid-filled sac that is contained within a shell or the uterus Figure 47.15 Amnion. The amnion protects the embryo in a fluid-filled cavity that prevents dehydration and cushions mechanical shock. Allantois. The allantois functions as a disposal sac for certain metabolic wastes produced by the embryo. The membrane of the allantois also functions with the chorion as a respiratory organ. Chorion. The chorion and the membrane of the allantois exchange gases between the embryo and the surrounding air. Oxygen and carbon dioxide diffuse freely across the egg’s shell. Yolk sac. The yolk sac expands over the yolk, a stockpile of nutrients stored in the egg. Blood vessels in the yolk sac membrane transport nutrients from the yolk into the embryo. Other nutrients are stored in the albumen (the “egg white”). Embryo Amniotic cavity with amniotic fluid Shell Albumen Yolk (nutrients) The three germ layers give rise to the four extraembryonic membranes of the amniotic egg that surround the developing embryo
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F. Mammalian Development The eggs of placental mammals Are small and store few nutrients Exhibit holoblastic cleavage Gastrulation and organogenesis resemble the processes in birds and other reptiles At the completion of cleavage the blastocyst forms The trophoblast, the outer epithelium of the blastocyst initiates implantation in the uterus, and the blastocyst forms a flat disk of cells As implantation is completed gastrulation begins and the extraembryonic membranes begin to form By the end of gastrulation the embryonic germ layers have formed
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Concept 47.2: Morphogenesis in animals involves specific changes in cell shape, position, and adhesion Changes in the shape of a cell usually involve reorganization of the cytoskeleton Early in embryonic development of an animal, a sequence of changes takes place that establishes the
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This note was uploaded on 05/04/2011 for the course BIO 119 taught by Professor O'donnellandspear during the Spring '07 term at SUNY Geneseo.

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lecture_18__2009 - Distinguished Alumni Panel 2 pm Friday...

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