Chapter 11. Cell communication.
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| Yeast sex cell types. a -- secretes a signaling molecule called the a factor which binds to the specific receptor proteins on ∝. ∝ -- secretes ∝ signaling molecule called the ∝ factor which binds to the specific receptor proteins on a. | ||
| The process by which a signal on a cell's surface is converted to a specific cellular response. | ||
| Close range communication. Both animals and plants have cell junctions that allow molecules to pass readily between adjacent cells without crossing plasma membranes. | ||
| Close range communication. Two cells in an animal may communicate by interaction between molecules protruding from their surfaces. | ||
| Local Signaling. A secreting cell acts on nearby target cells by discharging molecules of a local regulator (a growth factor, for example) into the extracellular fluid. local signaling in animal cells. | ||
| Local signaling. A nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell. | ||
| The narrow space between the nerve cell and its target cell. | ||
| Long distance signaling. Specialized cells release hormone molecules, which travel via the circulatory system to target cells in other parts of the body. | ||
| Origin of signal transduction pathways. | ||
| 1st stage of signaling. target cell's detection of a signaling molecule coming from the outside cell. a signal is 'detected' when it binds to the molecule receptor protein at the cells surface. | ||
| 2nd stage of signaling. after the bind, the signaling protein changes the receptor protein, initiating the process of transduction. converts the signal to a form that can bring about a specific cellular response. | ||
| sometimes transduction takes more than one step so it goes through the pathway. the molecules in the pathway are often called relay molecules. | ||
| 3rd stage of signaling. the transduced signal finally triggers a specific cellular response. | ||
| the signaling molecule. a molecule that specifically binds to another molecule, often a larger one. | ||
| their ligands are water-soluble and generally too large to pass freely through the plasma membrane. transmits information from the outside to the inside by changing shape when a specific ligand binds to it. | ||
| a plasma membrane receptor that works with the help of a G protein. | ||
| a protein that binds the energy-rich molecule GTP to a G protein-coupled receptor. functions as a molecular switch that is either on or off depending on if GDP or GTP is attached. GDP - inactive GTP - active | ||
| found in either the cytoplasm or nucleus of target cells | ||
| an enzyme that catalyzes the transfer of phosphate groups. | ||
| an enzyme that catalyzes the transfer of a phosphate group from ATP to the amino acid tyrosine on a substrate protein. | ||
| a type of membrane receptor containing a region that can act as a gate when the receptor changes shape. | ||
| the general name for an enzyme that transfers phosphate groups from ATP to a protein. | ||
| enzymes that can rapidly remove phosphate groups from proteins, a process called dephosphorylation. | ||
| many signaling pathways also involve small, nonprotein, water-soluble molecules or ions. spread through diffusion. they transmit the signal from the plasma membrane to the metabolic machinery in the cytoplasm. | ||
| an enzyme embedded in the plasma membrane which converts ATP to cAMP in response to an extracellular signal. | ||
| cleaves a plasma membrane phospholipid called PIP_2 into SAG and IP_3. calcium and IP_3 in signaling pathways | ||
| an enzyme that converts cAMP to AMP, inactivates cAMP. requires a surge of epinephrine to boost the cytosolic concentration of cAMP. | ||
| "the second messenger" is made from ATP by adenylyl cyclase and is then inactivated in AMP by phosphodiesterase. | ||
| a second messenger in many signal transduction pathways. produced by cleavage of a certain kind of phospholipid in the plasma membrane. | ||
| large relay proteins to which several other relay proteins are simultaneously attached which help speed up signal transduction pathways. | ||
| in multicellular organisms, one of the many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body to change their functioning. | ||
| a secreted molecule that influences cells near where it is secreted. | ||
| sometimes travel in vessels but more often reach their targets by moving through cells or by diffusing through the air as a gas. | ||
| specialized cells release hormone molecules, which travel via the circulatory system to target cells throughout the body | ||
| 1. reception 2. transduction 3. response | ||
| the immediate affect of the ligand on the receptor causes the aggregation of two or more receptor molecules, which leads to further molecular events inside the cell. | ||
| plasma membrane cytoplasm nucleus | ||
| when two receptor polypeptides associate closely with each other | ||
| the initial signaling molecule triggers a phosphorylation cascade. once phosphorylated, the last kinase in the sequence enters the nucleus and there activates a gene-regulating protein. this protein stimulates a specific gene so that an mRNA is synthesized, which then directs the synthesis of a particular protein in the cytoplasm. | ||
| the particular proteins a cell possesses determine what signaling molecules it responds to and the nature of the response. |
