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Eukaryotes and Cell Differentiation 2015/16 Lufukuja G 1 What are eukaryotic cells? Eukaryotic cells are more complex than prokaryotic cells. For example, prokaryotic cells such as bacteria do not have nuclei. All animal and plant cells have nuclei and are therefore eukaryotic. Each eukaryotic cell contains membrane-bound cell structures called organelles. The organelles are found inside the cell’s cytoplasm. A eukaryotic cell’s genetic material is contained within its nucleus. A cell membrane surrounds a eukaryotic cell and all its contents. Lufukuja G 2 Eukaryotic Prokaryotic Lufukuja G 3 Eukaryotes The human body is made up of many different kinds of cells. For example, the cells that make up your brain are very different from the cells that make up your muscles. Have you ever thought about how many different kinds of cells make up your body? What makes them different? How does the body make different kinds of cells? Do other organisms contain different types of cells? Lufukuja G 4 Lufukuja G 5 How do specialized cells form? Stem cells are unspecialized. One of the fundamental properties of a stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions. Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells Stem cells can give rise to specialized cells. When unspecialized stem cells give rise to specialized cells, the process is called differentiation. Lufukuja G 6 How do specialized cells form? 1. 2. There are two broad types of stem cells: Embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and Adult stem cells, which are found in various body tissues Lufukuja G 7 Lufukuja G 8 Lufukuja G 9 Lufukuja G 10 Lufukuja G 11 Lufukuja G 12 The ability of the cell to differentiate into different cell types (Potency) Totipotent stem cells can differentiate into embryonic and extraembryonic cell types. Such cells can construct a complete, viable organism. Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells, i.e. cells derived from any of the three germ layers. Pluripotent stem cells undergo further specialization into multipotent progenitor cells that then give rise to functional cells. Eg. Hematopoietic stem cells (adult stem cells) from the bone marrow that give rise to red blood cells, white blood cells, and platelets. Mesenchymal stem cells (adult stem cells) from the bone marrow that give rise to variety of cell types, including: osteoblasts, chondrocytes, myocytes and adipocytes. Lufukuja G 13 Totipotent Lufukuja G 14 Pluripotent Lufukuja G 15