a The total number of individuals in the population of Vibrio b The number of

A the total number of individuals in the population

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What are you measuring when using the hemacytometer? a. The total number of individuals in the population of Vibrio b. The number of individuals in a sample from the Vibrio population. c. The amount of light absorbed by a sample of Vibrio . d. The amount of light reflected by a sample of Vibrio . e. The amount of light that passes through a sample of Vibrio without being absorbed/scattered by cells.
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Why is developmental biology so interesting? How do two haploid cells fuse to form one diploid cell? What are the steps leading from that one diploid cell (zygote) to millions of differentiated cells? We’ll explore this question using: Sea Urchins
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Why Sea Urchin Development? Earlier embryonic stages similar to human embryos Eggs and embryos easy to work with Almost transparent Produce a relatively small number of cells Lack shells Always available Develop rapidly in sea water
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LOPHOTROCHOZOA Rotifera Platyhelminthes Annelida Molluska ECDYSOZOA Nematoda Arthropoda Echinodermata Chordata DEUTEROSTOMES Segmentation Radial symmetry (in adults) Segmentation Coelom, cephalization, CNS Protostome development Segmentation Loss of coelom BILATERIA PROTOSTOMES DEUTEROSTOMES From Biological Science, 4th edition by Scott Freeman Anus forms first Mouth forms first Sea Urchins Chickens, Humans
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Sea Urchin Spiny echinoderms- live in the ocean, eat kelp, food source for sea otters In lab this week, you will observe gametes (both sperm and egg), fertilization, and embryonic development of sea urchins.
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Stages in Sea Urchin Development Gametes (sperm & egg, 1N) Zygote (product of fertilization, 2N) Cleavage (initial cell divisions) Blastula (ciliated hollow ball of cells) Gastrula (formation of germ layers) Pluteus (swimming larvae) Adult (sedentary stage)
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Fertilized Eggs FERTILIZATION- leading to the formation of the fertilization membrane Purpose?
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Cleavage
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Blastocoel Cleavage and Blastulation in the Sea Urchin Blastomeres 206L Website- Sea urchin development timelapse video CLEAVAGE- rapid division of cells Formation of blastula Approximately 1000 cells Notice size of cells
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Blastula blastocoel
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LOPHOTROCHOZOA Rotifera Platyhelminthes Annelida Molluska ECDYSOZOA Nematoda Arthropoda Echinodermata Chordata DEUTEROSTOMES Segmentation Radial symmetry (in adults) Segmentation Coelom, cephalization, CNS Protostome development Segmentation Loss of coelom BILATERIA PROTOSTOMES DEUTEROSTOMES From Biological Science, 4th edition by Scott Freeman Anus forms first Mouth forms first Sea Urchins Chickens, Humans
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Events of Interest- Sea Urchin Gastrulation = movement and differentiation Movement of cells Ingression of mesenchyme cells to form mesoderm Outcome Embryonic germ layers mbryology_main.html Movie, 9.3
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Blastopore forms anus Mouth forms from secondary opening From Biological Science, 4th edition by Scott Freeman Deuterostomes
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Gastrula ectoderm endoderm mesoderm
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Gastrula archenteron Blastopore (forms anus)
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