01:119:116 Lecture Notes - Lecture 5: Blastocoel, Blastomere, Unikont
22 Sep 2018
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Ingest, then digest: cell structure, eukaryotic -fig 6. 8a, lack cell walls, multicellular, proteins external to pm. Fig 6. 28: organization, all have differentiated cells, most have differentiated tissues, higher forms have differentiated organs, have muscle and nerve cells. -> differentiates animals from plants and fungi: reproduction, usually sxual with 2n stage dominating life cycle, meiosis- produces sperm(n) and egg(n, fertilization. Fig 32. 2-3: cleavage- series of mitotic cell divisions without cell growth between divisions, blastula- hollow ball of cells that surround blastocoel, gastrulation- embryo folds inward, expands, and fills blastocoel. Produces gastrula with different layers of embryonic tissues: gastrula, endoderm- inner layer, ectoderm- outer layer, archenteron- pouch. Opens to outside via blastopore: some animals develop directly into adults, some animals- at least one larval stage, larva- sexually immature, different from adult, metamorphosis. Adult: development regulated by gene expression of developmental genes, homeobox genes. Code for proteins that regulate expression of developmental genes: control expression of many genes, homologous in all animals.
