CellCommunication
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Catégorie :Category: nCreator TI-Nspire
Auteur Author: RNDMPRSN
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 6.14 Ko KB
Mis en ligne Uploaded: 26/01/2025 - 20:37:11
Uploadeur Uploader: RNDMPRSN (Profil)
Téléchargements Downloads: 2
Visibilité Visibility: Archive publique
Shortlink : http://ti-pla.net/a4478546
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 6.14 Ko KB
Mis en ligne Uploaded: 26/01/2025 - 20:37:11
Uploadeur Uploader: RNDMPRSN (Profil)
Téléchargements Downloads: 2
Visibilité Visibility: Archive publique
Shortlink : http://ti-pla.net/a4478546
Description
Fichier Nspire généré sur TI-Planet.org.
Compatible OS 3.0 et ultérieurs.
<<
What are some ways that cells communicate? " Local signaling " Autocrine Signaling " Juxtacrine Signaling " Paracrine Signaling " Synaptic Signaling " Long distance signaling " Endocrine Signaling 1) Local Signaling A) Autocrine " A cell sends a specific signal that is received by the same cell " A cell stimulates a response in itself B) Juxtacrine " Direct contact between cells " Cell junctions directly connect the cytoplasm of adjacent cells Gap junctions between animal cells Plasmodesmata between plant cells " Ex: cardiac cells for rhythmicity " Surface receptors can give/send information " Ex: specific immune response Cell-cell recognition. Two cells in an animal may communicate by interaction between molecules protruding from their surface. E.g. Helper T- Cell Response C) Paracrine Signaling " Chemical messengers are released by a signaling cell " Chemicals travel short distances to target cells in the vicinity. " Example: " Growth factors (local regulator) stimulate nearby target cells to grow and divide. D) Synaptic Signaling " Specialized type of signaling " Occurs in the nervous system " Neurotransmitter is released " Triggers a response in the target cell 2) Long Distance Signaling A) Endocrine Signaling Endocrine cell Blood vessel Both plants and animals use hormones (e.g. Insulin) Hormone travels in bloodstream to target cells " Can affect many cells in other parts of the body " Any target cells with the correct receptor can respond to signal. Target cell (c) Hormonal signaling. Specialized endocrine cells secrete hormones into body fluids, often the blood. Hormones may reach virtually all body cells. Signal Transduction Pathways Signal Transduction Pathways " Convert signals on a cells surface into cellular responses " Similar in microbes and mammals, suggesting an early origin Examples of evolutionary significance " Yeast cells signal for sexual reproduction through a signal transduction process. 1 Exchange of mating factors. Each cell type secretes a mating factor that binds to receptors on the other cell type. Mating. Binding of the factors to receptors induces changes in the cells that lead to their fusion. " Quorum Sensing " Bacteria secrete chemical signals to communicate with other bacteria " Coordinate gene expression according to the density of their local population. " Example: to launch virulence on large host Steps in a typical signal transduction pathway STEP 1: Reception § Reception occurs when a signal molecule (ligand) binds to a receptor protein, causing it to change shape. § Receptor protein is on the cell surface or inside the cell. § Ligand and receptor have a unique bond Types of Receptors " There are three main types of plasma membrane receptors: " G-protein-linked " Tyrosine kinases " Ion channel G-protein-linked receptors " Very common, diverse functions " Only results in single pathway response Receptor tyrosine kinases " Multiple pathway response " Regulates/coordinates many cell functions " E.g. growth, development, differentiation Ligand-gated ion channel receptor " When ligand binds, channel can open or close. Plasma Membrane Gate open " Ex: neurotransmitters bind as ligands for ion channels Cellular response Gate close Intracellular Receptors § Target protein is INSIDE the cell Hormone EXTRACELLULAR (testosterone) FLUID Plasma membrane Receptor protein Hormonereceptor complex § Ligand must be a hydrophobic molecule DNA mRNA NUCLEUS CYTOPLASM New protein 1 The steroid hormone testosterone passes through the plasma membrane. 2 Testosterone binds to a receptor protein in the cytoplasm, activating it. 3 The hormonereceptor complex enters the nucleus and binds to specific genes. 4 The bound protein stimulates the transcription of the gene into mRNA. 5 The mRNA is translated into a specific protein. STEP 2: Transduction " Signaling cascades that relay signals to the target " May occur by one protein or by several proteins activating each other in a cascade. " Relay molecules " Usually large proteins " They do not diffuse through the cell quickly " Require activation Second Messengers " Small, water soluble molecules " Diffuse across the cell membrane quickly " More abundant than first messenger à AMPLIFY SIGNAL à Bring greater cellular response " May or may not need activation before they are able to move the signal on to the next step in the process. " Examples: Cyclic AMP (cAMP) and calcium ions (Ca2+) in human systems. 7 9/16/2020 Example: Cyclic AMP " Important in the pathway responsible for the breakdown of glycogen in the liver and skeletal muscles to glucose. " 1st messenger: epinephrine " Binds to G protein linked receptor and catalyzes the conversion of ATP to cAMP Phosphorylation Cascade " Often involves a series of proteins called kinases: " Adds a phosphate to the next protein in line, activating it, and sending the signal to the target " Enzymes then remove the phosphates to reset the cascade 5 Enzymes called protein phosphatases (PP) catalyze the
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>>
Compatible OS 3.0 et ultérieurs.
<<
What are some ways that cells communicate? " Local signaling " Autocrine Signaling " Juxtacrine Signaling " Paracrine Signaling " Synaptic Signaling " Long distance signaling " Endocrine Signaling 1) Local Signaling A) Autocrine " A cell sends a specific signal that is received by the same cell " A cell stimulates a response in itself B) Juxtacrine " Direct contact between cells " Cell junctions directly connect the cytoplasm of adjacent cells Gap junctions between animal cells Plasmodesmata between plant cells " Ex: cardiac cells for rhythmicity " Surface receptors can give/send information " Ex: specific immune response Cell-cell recognition. Two cells in an animal may communicate by interaction between molecules protruding from their surface. E.g. Helper T- Cell Response C) Paracrine Signaling " Chemical messengers are released by a signaling cell " Chemicals travel short distances to target cells in the vicinity. " Example: " Growth factors (local regulator) stimulate nearby target cells to grow and divide. D) Synaptic Signaling " Specialized type of signaling " Occurs in the nervous system " Neurotransmitter is released " Triggers a response in the target cell 2) Long Distance Signaling A) Endocrine Signaling Endocrine cell Blood vessel Both plants and animals use hormones (e.g. Insulin) Hormone travels in bloodstream to target cells " Can affect many cells in other parts of the body " Any target cells with the correct receptor can respond to signal. Target cell (c) Hormonal signaling. Specialized endocrine cells secrete hormones into body fluids, often the blood. Hormones may reach virtually all body cells. Signal Transduction Pathways Signal Transduction Pathways " Convert signals on a cells surface into cellular responses " Similar in microbes and mammals, suggesting an early origin Examples of evolutionary significance " Yeast cells signal for sexual reproduction through a signal transduction process. 1 Exchange of mating factors. Each cell type secretes a mating factor that binds to receptors on the other cell type. Mating. Binding of the factors to receptors induces changes in the cells that lead to their fusion. " Quorum Sensing " Bacteria secrete chemical signals to communicate with other bacteria " Coordinate gene expression according to the density of their local population. " Example: to launch virulence on large host Steps in a typical signal transduction pathway STEP 1: Reception § Reception occurs when a signal molecule (ligand) binds to a receptor protein, causing it to change shape. § Receptor protein is on the cell surface or inside the cell. § Ligand and receptor have a unique bond Types of Receptors " There are three main types of plasma membrane receptors: " G-protein-linked " Tyrosine kinases " Ion channel G-protein-linked receptors " Very common, diverse functions " Only results in single pathway response Receptor tyrosine kinases " Multiple pathway response " Regulates/coordinates many cell functions " E.g. growth, development, differentiation Ligand-gated ion channel receptor " When ligand binds, channel can open or close. Plasma Membrane Gate open " Ex: neurotransmitters bind as ligands for ion channels Cellular response Gate close Intracellular Receptors § Target protein is INSIDE the cell Hormone EXTRACELLULAR (testosterone) FLUID Plasma membrane Receptor protein Hormonereceptor complex § Ligand must be a hydrophobic molecule DNA mRNA NUCLEUS CYTOPLASM New protein 1 The steroid hormone testosterone passes through the plasma membrane. 2 Testosterone binds to a receptor protein in the cytoplasm, activating it. 3 The hormonereceptor complex enters the nucleus and binds to specific genes. 4 The bound protein stimulates the transcription of the gene into mRNA. 5 The mRNA is translated into a specific protein. STEP 2: Transduction " Signaling cascades that relay signals to the target " May occur by one protein or by several proteins activating each other in a cascade. " Relay molecules " Usually large proteins " They do not diffuse through the cell quickly " Require activation Second Messengers " Small, water soluble molecules " Diffuse across the cell membrane quickly " More abundant than first messenger à AMPLIFY SIGNAL à Bring greater cellular response " May or may not need activation before they are able to move the signal on to the next step in the process. " Examples: Cyclic AMP (cAMP) and calcium ions (Ca2+) in human systems. 7 9/16/2020 Example: Cyclic AMP " Important in the pathway responsible for the breakdown of glycogen in the liver and skeletal muscles to glucose. " 1st messenger: epinephrine " Binds to G protein linked receptor and catalyzes the conversion of ATP to cAMP Phosphorylation Cascade " Often involves a series of proteins called kinases: " Adds a phosphate to the next protein in line, activating it, and sending the signal to the target " Enzymes then remove the phosphates to reset the cascade 5 Enzymes called protein phosphatases (PP) catalyze the
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