Chapter 6-10 AP Biology
Define phagocytosis and pinocytosis. What does it mean for a cell to have a concentration gradient?
Signal Transduction Pathway- a specific cellular response as a result of a received cellular signal.
Local Regulators- influence cells in the nearby vicinity. Paracrine Signaling- broad range- can communicate with many cells. Synaptic Signaling- occurs in the nervous system (more specific)
Hormones- chemicals that aide in long distance signaling- released by specialized cells and travel in the blood stream.
Reception- the target cell’s detection of a chemical signaling molecule. (when the molecule binds to the receptor protein). Transduction- the change that occurs on the protein due to the receptor binding. Response- transduced signal triggers a specific cellular response.
G Protein Coupled Receptors (GPCRs)- signaling molecule binds to GPCR which activates it and changes its shape. GPCR then binds an inactive G protein causing GDP to convert to GTP, activating the G protein. Protein binds to enzyme, activating it- triggering the next step in a cellular response.
Receptor Tyrosine Kinases (RTKs)- transfer phosphates from ATP to the amino acid tyrosine.
Ion Channel Receptors- includes a region that acts as a fate when the receptor changes shape. Gate can open or close to allow flow of specific ions.
Intracellular Receptors- found in the cytoplasm or nucleus of target cells.
What are the three stages of cell signaling? What are the two types of local signaling? Which is the strongest? Hint: When a signal is transmitted to numerous molecules, it is more amplified because it activates more than one molecule at the end of a pathway. How are long-distance signals sent? What are the three main types of transmembrane receptors?
Protein Kinase- enzyme that transfers phosphate groups from ATP to a protein. Phosphorylation- adding a phosphate (which many times activates the protein)
Protein Phosphatase- enzyme that rapidly remove phosphate groups from proteins, a process called dephosphorylation. Usually inactivates protein kinases and help turn off signal transduction pathway. Makes protein kinases available for reuse.
Second Messengers- small, water-soluble, non-protein molecules/ions involved in signaling pathways. Cyclic AMP (cAMP)- (cyclic adenosine monophosphate)- ATP is converted to cAMP by an enzyme (adenylyl cyclase) in the plasma membrane in response to an extracellular signal (usually a hormone). Phosphodiesterase- reduces cAMP to AMP
cAMP usually activates protein kinase A which phosphorylates other molecules in the signal transduction pathway.
Calcium (Ca 2+ ) Ion- calcium pumps actively transport calcium ions from the cytoplasm out of the cell or into the ER.
Signaling pathway may regulate protein activity or synthesis.