10/20 & 10/22 Notes
10/20 & 10/22 Notes BIOL 11100 - 001
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BIOL 11100 - 001
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This 9 page Class Notes was uploaded by Brianna Nemeth on Thursday October 22, 2015. The Class Notes belongs to BIOL 11100 - 001 at Purdue University taught by Denise Lore Zielinski, Mark Edward Browning in Fall 2015. Since its upload, it has received 18 views. For similar materials see Fundamentals Of Biology II in Science at Purdue University.
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Date Created: 10/22/15
Thursday 1022 Signal transduction pathway that leads to a cellular response model Kinds of Signaling 0 Direct CelltoCell Contact Communicate via gap junctions or surface receptors Autocrine Cell signaling to itself 0 Paracrine cell signaling to nearby cells 0 Endocrine Systemic signaling via hormones and circulatory system Synaptic chemical signals released by neurons across a gab to a target cell Two kinds of receptors Cytoplasmic receptors intracellular Signa is usually hydrophobic hormone or small molecules that pass through plasma membrane Membrane receptos Signas cannot pass plasma membrane Receptors are transmembrane proteins Receptor transmits signal May utilize 2nCI messenger intracellular signal Steroid Hormone receptors 0 Site of action is in nucleus 0 Usually found in the cytoplasm Action is direct Hormone crosses membrane by diffusion Binds to receptor in cytoplasm Hormonereceptor complex moves into the nucleus Change patterns of gene expression Steroids affect gene expression directly by making up part of a transcription factor model Kinds of Membrane Receptors Channellinked receptors Found in nerve synapses Enzymatic catalytic receptors Many hormone and growth factor receptors G Proteincoupled receptors activates other molecules Diverse receptor type mportant signaling pathways Vision and other senses Exchanges GTP to activate other molecules Pharmaceuticals Many drugs target membrane receptors Can be agonists or antagonists Agonists mimics action of ligand Antagonist prevents action of ligand Estimated that over 50 of drugs target transmembrane receptors Channel Linked Receptors Receptor function linked to ion channel Differential ion concentrations create voltage across membranes Action is direct Ligand binds receptor Channel openscloses allowing ion ux Catalytic Receptors lnternal portion of receptor is enzyme usualy protein tyrosine kinase ca receptor tyrosine kinase Addoes P04 to amino acid tyrosine in proteins Autophosphorylation activates receptor Active RTK phosphorylates other proteins Binds adapter proteins mediate response Phosphotyrosine binding proteins Signal transduction through a receptor kinase model Example Growth Factor Receptor Growth factor receptors usually RTKs More than 90 RTKs in humans Protein kinase phosphorylation cascade Each kinase acts on another kinase Ultimately changes cellular function Example activate cyclindependent kinase cdk involved in cell cycle regulation Protein kinase cascade can ultimately lead to the activation of transcription factors model 2ncl Messengers Ligand1st messenger interacts with membrane receptor Receptor is bifunctional molecule Extracellular bind ligand ntraceluar change cells activity May require internal 2ncl messenger Receptor conveys info Intracellular messenger G ProteinCoupled Receptors Common signal transduction pathway Receptors have common structure 7 transmembrane domain structure 0 Receptor interacts with Gprotein bind GTPGDP active bound to GTP Inactive bound to GDP GPCR link receptor and effector proteins Mechanism of Action Ligand activates receptor by binding Receptor activates G protein G protein activation exchange GDP to GTP Effectors2ncl Messengers Adenylyl Cyclase Catalyzes ATP gtgtgtgt cAMP conversion cAMP turns on Protein Kinase A PKA Phospholipase C Acts on inositol phospholipids Concerts PIP2 gtgtgt IP3 DAG Causes release of intracellular Ca2 cAMP is made from ATP Common 2ncl Messengers o cAMP Formed by effector protein adenylyl cyclase cAMP activates Protein Kinase A PKA Ca2 Produced by many pathways IP3 receptors release Ca2 from ER Many effects including muscle contraction Activating Protein Kinase C PKC Relevance to Human Disease 0 Infectious Disease Disturb signal transduction pathways Cholera toxin produced by V cholera targets G protein that turns on adenylyl cyclase results in diarrhea and dehydration because ion channels in large intestine are left open Hereditary Diseases Many affect G proteins Many affect GPCR