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WinterTest.docx

WinterTest.docx - Objectives As a result of their studies...

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Objectives: As a result of their studies in this unit, a student should be able to: Describe different ways cells can communicate with each other. Paracrine Signaling Secretions from one cell have an effect only on cells in the immediate area Short-lived, local effects Influence restricted to cells in immediate vicinity of releasing cell Autocrine signaling Reinforces developmental changes Important component of signaling in the immune system Long, fiber-like extensions release neurotransmitters from tips to target cells Releases molecules that then bind to receptors on that same cell’s membrane INduces a response Synaptic signaling Chemical synapse signaling involves transmission of neurotransmitters From a neuron over a small synaptic cleft to target cell Endocrine Signaling Hormones are released into circulatory system to carry target cells Signal molecule that remains in the extracellular fluid that travels throughout body Longer-lived molecules ( hormones ) affective cells distant from releasing cells Direct Contact Two cells in direct contact w each other may send signals across gap junctions Some molecules on membrane of one cell can be recognized by receptors of a membrane on another cell Cells of early dvlpt occur in direct contact Compare and contrast five types of chemical signal pathway mechanisms. you should be able to explain these! Ligand gated ion channels Voltage gated ion channels G-Protein Coupled Receptor Tyrosine Kinase Receptor Cytoplasmic Receptor-Transcription Factor Hydrophobic receptor RTK Compare and contrast receptor types found in cells. Intracellular receptors No extracellular signal binding site Receives signals from lipid soluble or non-charged, non-polar small molecules
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ligand generally binds to the receptor and that complex goes into the nucleus to either act as a transcription factor or to activate a transcription factor that will increase the rate of transcription of a gene into protein. Ex) Receptors for NO, steroid hormone, vitamin D, thyroid hormone Cell Surface Receptors Chemically gated ion channels Multipass transmembrane protein forming a central pore Molecular gates triggered chemically to open/close Ex) neurons Enzymatic receptors (RTK) Single-pass transmembrane protein Binds signal extracellularly Catalyzes response intracellularly Activates protein kinase enzymes by adding phosphate groups to proteins Ex) Phosphorylation of protein kinases G Protein Coupled Receptors Seven pass transmembrane protein with cytoplasmic binding site for G protein Binding of signal to receptor causes GTP to bind a G protein G Protein with attached GTP detaches to deliver the signal inside the cell Ex) Peptide hormones, rod cells in the eyes Compare and contrast water-soluble hormone and lipid-soluble hormone signal mechanisms.
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