AP Biology Notes - Ch. 11 & 12

AP Biology Notes - Ch. 11 & 12 - TEXTBOOK...

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TEXTBOOK ASSIGNMENT Chapter 11 1. Describe the basic signal-transduction pathway in yeast and explain why it is believed that these pathways evolved before multicellular organisms appeared on earth. The yeast Saccharomyces cerevisiae identifies its mates by chemical signaling. There are two sexes, a and alpha , each of which secretes a specific signaling molecule, a factor and alpha factor respectively. These factors each bind to receptor proteins on the other mating type. Once the mating factors have bound to the receptors, the two cells grow toward each other and experience other cellular changes. Two opposite cells fuse, or mate. The a/ alpha cell contains the genes of both cells. The molecular details of signal transduction in yeast and mammals are strikingly similar, even though the last common ancestor of these two groups of organisms lived over a billion years ago. The cell–signaling mechanisms used today evolved well before the first multicellular creatures appeared on Earth. There are two sexes, or mating types, called a and α. Cells of mating type a secrete a chemical signal called a factor, which can bind to specific receptor proteins on nearby α cells. At the same time, α cells secrete α factor, which binds to receptors on a cells. Without actually entering the cells, the two mating factors cause the cells to grow toward each other and bring about other cellular changes. The result is the fusion, or mating, of two cells of opposite type. The new a/α cell contains all the genes of both original cells 2. Create a chart for the category of chemical signals. Include proximity to communicating cells and examples. Signal Description Type of Signaling Paracrine signaling The signals are molecules secreted by a cell called local regulators. These local regulators influence cells in the vicinity. These chemical signals are released into the extracellular fluid and adjacent cells respond to a local regulator. The influenced, responding cells are called target cells. Local Signaling Synaptic signaling: a nerve cell releases neurotransmitter molecules into a synapse, the narrow space between the transmitting nerve cell and the target cell. Short distance signaling Hormonal signaling Is a long distance signaling. The specialized secreting cells, endocrine cells, release the chemical signals or regulators into the blood, which distributes the hormones throughout the body. Long distance signaling 3. List and describe the 3 main stages of cell signaling. Include the characteristics of the ligand-receptor interaction and how these interactions are involved in initiation. Three Main Stages of Cell Signaling: Multicellular organisms also release signaling molecules that target other cells. Some transmitting cells release local regulators that influence cells in the local vicinity. Paracrine signaling occurs when numerous cells can simultaneously receive and respond to growth factors produced by a single cell in their vicinity.
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