Gene Expression and Specialized Cells Multicellular Organisms Organisms

Gene Expression and Specialized Cells

Multicellular Organisms § Organisms that are made up of many cells are called multicellular (YOU!). § All multicellular organisms depend on communication and cooperation among specialized cells § They have different kinds of cells doing different jobs

Cell Specialization § Cells throughout an organism can develop in different ways to perform different tasks. Also called cell differentiation § Undifferentiated cells, or stem cells, are cells that have not yet specialized (Don’t have a job) § Differentiated cells are specialized cells (have a job) undifferentiated

Specialized Animal Cells Cheek (epithelial) cells Red blood cells Muscle cells

What is cell differentiation? • Differentiation is the process by which cells become specialized and take on specific roles in an organism. • During human develo pment, a single cell (a fertilized egg) differentiates into every different kind of specialized cell type found in the body, including blood, muscle, and nerve cells. • Cells that are undifferentiated are known as stem cells. Stem cells are found in embryos (embryonic stem cells) and in adults (adult stem cells). A nerve cell

What is the role of DNA in cell differentiation? • Nearly all cell types in a large organism contain the same DNA, yet they express their genes differently depending on the proteins needed in the cells, • Gene expression describes the way in which genetic information is put into action (by making proteins). Not all genes are turned on in every cell. (remember heart cell genes are not turned on in the eyeball!)