Term
| What are the sexes of Saccharomyces cerevisiae, a type of yeast cell? |
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Definition
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Term
| How do types of the aforementioned yeast reproduce? |
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Definition
| Cells of mating type a secrete a signalling molecule, called a factor, which can bind to specific receptor proteins on nearby alpha cells. Alpha cells release an alpha factor as well, which binds to receptors on a cells. These factors cause the cells to grow towards each other and fuse. The new cell contains all the genes of both original cells. |
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Term
| Signal Transduction Pathway |
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Definition
| The process by which a signal on a cell's surface is converted to a specific cellular response. |
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Term
When do scientists think signaling mechanisms first evolved?
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Definition
| In ancient prokaryotes and single celled eukaryotes and then were adopted for new uses by their multicellular descendents. Cells of many bacterial species secrete small molecules that can be detected by other bacterial cells. This is how bacteria can sense the local density of bacterial cells - called quorum sensing. |
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Term
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Definition
| The phenomenon of bacteria cells sensing the density of other bacteria cells in an area by the release of signaling molecules |
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Definition
| junctions that allow molecules to pass readily between adjacent cells without crossing plasma membranes. |
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Definition
| Two cells in an animal may communicate by interaction between molecules protruding from their surfaces. |
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Term
| What are two types of local signalling? |
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Definition
| Paracrine signaling and Synaptic signaling |
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Term
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Definition
| A secreting cell acts on nearby target cells by discharging molecules of a local regulator into the extracellular fluid. |
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Definition
| A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell. |
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Term
| What is an example of long-distance signaling |
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Definition
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Term
| What is hormonal signaling? |
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Definition
| Specialized endocrine cells secrete hromones into body fluids, often into the blood. Hormones may reach virtually all body cells. |
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Definition
| compounds that stimulate nearby target cells to grow and divide. |
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Term
| What is another name for plant hormones? |
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Definition
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Term
| How do plant growth regulators reach their targets? |
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Definition
| Sometimes by traveling in vessels, but more often by moving through cells or by diffusing through the air as a gas. |
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Term
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Definition
| a gas that promotes fruit ripening and helps regulate growth |
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Term
| What is an example of long-distance signaling? |
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Definition
| the transmission of a signal through the nervous system. |
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Term
| What are the three stages of cell signaling? |
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Definition
| Reception, Transduction and Response |
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Term
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Definition
| Investigated how animal hormone, epinepherine stimulated the breakdown of glycogen. Discovered that epinepherine somehow activates a cytosolic enzyme, glycogen phosphorylase, but ONLY when the cells in the test-tube were intact. This told him that the plasma membrane needed to be intact for the reaction to occur. |
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Term
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Definition
| Reception is the target cell's detection of a signaling molecule coming from outside the cell. A chemical signal is 'detected' when the signaling molecule binds to a receptor protein located at the cell's surface or inside the cell. |
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Term
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Definition
| The binding of the signaling molecule changes the receptor protein in some way. The transduction stage converts the signal to a form that can bring about a specific cellular response. |
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Definition
| The transduced signal finally triggers a specific cellular response. |
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Term
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Definition
| A molecule that specifically binds to another molecule - often a larger one, and generally causes the receptor protein to undergo a change in shape |
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Term
| G Protein-coupled receptor |
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Definition
| A plasma membrane receptor that works with the help of a G-Protein. Many different signaling molecules use tehse type of receptors, including yeast mating factors, epinephrine, and many other hormones. They all have seven alpha helices spanning the membrane. |
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Term
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Definition
| a protein that binds the energy-rich molecule GTP |
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Term
| How do G Protein Coupled receptors work? |
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Definition
| There are usually 3 parts; 1 g protein coupled receptor, a G protein, which has two forms, inactive and active, and an enzyme. When a signaling molecule binds to the receptor, it changes shape and binds the G-protein's inactive form, GDP, and replaces it with GTP. The GTP then dissassociates from the receptor and binds to the enzyme, activating it. The enzyme then triggers the next step in the pathway, which leads to a cellular response. The GDP is released, along with an inorganic phosphate. |
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