Membrane Proteins: Structure and Function PDF

 Give specialized function to membranes Diverse functions: receptors, transporters, enzymes, and structural MEMBRANE elements PROTEINS...

 Give specialized function to membranes Diverse functions: receptors, transporters, enzymes, and structural MEMBRANE elements PROTEINS Classification transporta * Hemoglobina CO2. oxigeno y ↑ mayormente  10.2 Membrane Proteins: Structure and Basic Functions Biological membranes contain integral, lipid-anchored, and peripheral proteins. Integral membrane proteins contain one or more hydrophobic membrane-spanning domains. Transmembrane proteins and glycolipids are asymmetrically oriented in the bilayer. Non-ionic detergents selectively extract transmembrane proteins. Sin denaturalizarias *. Biological membranes contain integral, lipid- anchored, and peripheral proteins. o arri = * electrostatic interactions  Proteins in a myelinated neuron https://pdb101.rcsb.org/sci- art/goodsell-gallery/myelin  Peripheral membrane proteins ↳ can associate to integral membrane protein or lipid bilayer. Associate to the surface of the lipid bilayer or to integral membrane proteins. I transmembrane proteins https://www.mdpi.com/2077-0375/11/5/346/htm  Membrane Binding Domains https://doi.org/10.1016/B978-0-12-374920-8.00519-1  ways 3 binding Lipid-anchored Vacylation (Ngemeinal) & cytosolic (inal) membrane proteins prenylation ~ extracewarEvGPI-anchor Lcms) ↑ used in cell signaling glucolipidos Are bound covalently to one or more lipid molecules. fatty acid glycine H 8 t Il cine Heine Mo- - NH3 residue residue + electrostatic bond acylation - area citoslica principalmente en el Figure 10-19  Human ABO blood group antigens. Figure 10-20  Table 10-2 - ABO Blood Groups Antigens on Serum Can Receive Blood Blood Group RBCs* Antibodies Types A A Anti-B A and O B B Anti-A B and O Receptor AB universal A and B None All O Anti-A and anti- Donante universal O B O * See Figure 10-20 for antigen structures.  ¿Cuál de las siguientes está asociada más débilmente a la bicapa? sintetiza enzima que citusina pirimidinas : zimina uracil · receptor - > - membrane - spanning -helix  LETC) re Mitocondria aa interacin Biochemical Society Transactions (2020) https://doi.org/10.1042/BST20190787 Transmembrane Proteins https://www.mdpi.com/2077-0375/11/5/346/htm  tend to form ↑ dimers Structure of glycophorin A, a typical single-pass transmembrane protein. 3 x-helix > arginina visika- Figure 10-14   * solu demuestra C-helix Hydropathy Plots. demuestran transmembrane domain valores ⑦. sada es un * - pico hidrofobicidad. - parecida a G-protein coupled receptor > - cuantas pasa hidrotobicos veces penbrana. hidrosilicos Structural models of two multipass membrane proteins. Figure 10-15  Agua X-helix & channel ce-transmembrane puede pasar por la T ↑ distintasregionsenteta - activa ↓ la proteina T eunidad pasadd homotetramer maternary protein DOI:10.3390/cells8020082 Annular lipids Le ↳ dan al estabilidad grupo de proteinas pq interaction con los fostolipidos de la membrana y ast los an polares no se repulsar en el centro de La membrana. Figure 10-16 Charged residues can orchestrate the assembly of multimeric membrane proteins. - electrostatic interactions T-cells receptor de pe aminoacidos con carga (polares) A Podemos fener son el centro del canal, pero en - en menor cantidad en comparacion a los aa hidrofbicos. Figure 10-17  of Aquaporins are not poing Porins. Transmembrane portion of a β- barrel membrane protein is a segment aout 10 amino acids long. In β-sheet secondary structure, alternate aminoacid residues are pointed in opposite directions. aa - inside * Hydrophilic aa - outside * Hydrophobic Figure 10-18  1972 – Singer and Nicolson Fluid-Mosaic Model – “Central Dogma” of membrane biology – Fluid lipid bilayer – two dimensional fluid – Proteins distributed differently Mosaic of discontinuous particles Science. 1972 Feb 18;175(4023):720-31. The fluid mosaic model of the structure of cell membranes. Singer SJ, Nicolson GL.  Transmission Electron Microscopy ? Freeze-fracture replication and etching In freeze-fracture replication, frozen tissue is fractured with a knife. –A heavy-metal layer is deposited on fractured surface. –A cast of the surface is formed with carbon. –The metal-carbon replica is viewed in the TEM. In freeze-etching, a layer of ice is evaporated from the surface of the specimen prior to coating it with heavy metal. "sandwich model " T &  Transmembrane proteins can be removed from membranes by detergents are formana proteins * Peripheral removed by high salt Trabajan ↳ concentrations. ↳ denature proteins ↳ electroforesis mas se utiliza * que ↳ do not denature proteins Figure 10-22 mas que se utiliza *  Solubilization of integral membrane proteins by non-ionic detergents. protein-detergent micelles Protein solubilization is a critical preparatory step in any in vitro experiment on membrane proteins Figure 10-23 WHAT RESTRICTS PROTEIN MOBILITY OR PHOSPHOLIPID DIFFUSION? Fluorescence recovery after photobleaching (FRAP) experiments can quantify the large-scale lateral movement of proteins and lipids within the plasma membrane. Figure 10-10  1970 - Frye and Edidin and * Lipids can roteins P diffuse laterally. Rotational diffusion Lateral diffusion * hay movimiento lateral de proteinas Many Membrane Proteins Diffuse in the Plane of the Membrane Cells Can Confine Proteins and Lipids to Specific Domains Within a Membrane azucares ↓ A. Protein Complexes B. Tethered by macromolecular assemblies outside the cell C. Tethered by macromolecular assemblies ↳ citoesqueleto inside the cell desmosomes D. Intercellular protein-protein interactions ⑪ E. Protein-lipid interactions (lipid rafts) ↳ mucho colesteral  - Gran mayoria de las infecciones/bacterias ocurren en los lipid ratts. Lipid rafts are transient, relatively ordered membrane domains, - whose formation is driven by lipid– lipid interactions. microdomains · transporte a · seralizacion ↑ senalizacin * el virus no entraj entra su material genetico.  acylation Regulation of prenylation membrane domains - peripheral proteins  KEY CONCEPTS OF SECTION 10.2 Biological membranes usually contain integral (transmembrane) proteins as well as lipid- anchored proteins and peripheral membrane proteins, which do not enter the hydrophobic core of the bilayer (see Figure 10-1). Most integral membrane proteins contain one or more membrane-spanning hydrophobic α helices, which are bracketed by hydrophilic domains that extend into the aqueous environment surrounding the cytosolic and exoplasmic faces of the membrane (see Figures 10-14, 10-15, and 10-17). Fatty acyl side chains as well as the polar head groups of membrane lipids pack tightly and irregularly around the hydrophobic segments of integral membrane proteins (see Figure 10-16). The porins, unlike other integral membrane proteins, contain membrane-spanning β sheets that form a barrel-like channel through the bilayer (see Figure 10-18). Lipids attached to certain amino acids anchor some proteins to one or the other membrane leaflet (see Figure 10-19). All transmembrane proteins and glycolipids are asymmetrically oriented in the bilayer. Invariably, carbohydrate chains are present only on the exoplasmic surface of a glycoprotein or glycolipid. Transmembrane proteins can be selectively extracted from membranes with the use of non-ionic detergents. 10.3 Phospholipids, Sphingolipids, and Cholesterol: Synthesis and Intracellular Movement Cells synthesize new membranes by the expansion of existing membranes. Membrane lipids contain saturated/unsaturated fatty acids of various chain lengths. Fatty acids are synthesized in ER and moved to the other leaflet by flippases and to other membranes by multiple mechanisms. convertea neonate ciclos e esteroide complesto por y con Hydroxymethyl glutaryl te HMG-CoA reductase catalyzes the cholesterol biosynthesis rate-controlling step.  have 14 , 18 20 caroons to can , Regulation of fatty acid synthesis Acetyl Cot · fatty acids and triglycerides in the cytosol are mainly synthesized. coA acids are synthesized from 2 acctyl. fatty Phosphoglycerides are mainly synthesized · · in the ER membrane.  Binding of a fatty acid to the hydrophobic pocket of a fatty acid–binding protein (FABP). ↳ cytosolic protein ↳ chaperones that permit B-sheet the transport > - * hydrophobic center of patty auds. amino acids · hydrophobic * interaccion no covalente entreacidos - y la proteina. grasos acid fatte Figure 10-24 Cells synthesize new membranes by the expansion of existing membranes. der A Phospholipid synthesis in the ER membrane. vor l ~ nusy summe Figure 10-25  Lipid Synthesis ⚫ Fatty acids and triglycerides ⚫ Cytoplasm ⚫ Phophoglycerides ⚫ SER ⚫ RER ⚫ Mitochondria (PE) Sphingolipids RER, Golgi de los * La mayoria procesos  Cholesterol biosynthetic pathway.D medi c amento s gib and the ER. ↳ synthesis in the cytosol inhibe loS - sinin an - * clulas hepaticas L sh con para e const cabo rate limiting llevan 3 a sintesis de ↓ Step la colesterd in mas are abumdanci que n 4 12 Figure 10-26 *de eleidentidad cada cantidad e diferente de tostolipids.  Modifying the lipid composition of membranes NO USA ATP ↑ Moves Scrambalase = bidirectionally. phospholipids flippase = moves phospholipids in one direction. ↳ Usa ATP Proposed mechanisms of transport of cholesterol and phospholipids between membranes. (fABPs) Plasma Membrane (General Biology Textbook) Plasma Membrane (General Biology Textbook) Fibers of extracellular matrix (ECM) Glyco- Carbohydrate protein Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Cholesterol Microfilaments Peripheral of cytoskeleton proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE History of Fluid Mosaic Model ↳ Distribution de neterogenea componentes en cada leaflet Patchwork Quilt Model se cree > - mudelo que enemos en nuestra membrana.  Main Functions of Biological Membranes Cell boundary permeabilidadseccivaus) re Permeability barrier Cell transport Cell communication (receptores) Cell- cell, Cell-matrix interactions  All cells are surrounded by the plasma membrane of lo que no tiene son organelos membranosos clas prodrotas yeucaiota. * FIGURE 1-12 FIGURE 1-13  All biological membranes have a common general siempre structure A a proteinas lipidos asociadas crean covalentes interacciones cansoniaratos. - estan nacia el & lado exterior region hidrosilica compuestos polares * Chidrofilicos) se region a traves hidrofobica transportan de proteinas integrales. -interaccion no-covalente de proteina zina * Interacciones entre no-covalentes. fosfolipidos son TEM Plasma Membrane drils Osmium tetroxide is used in EM both as a fixative and as a heavy metal stain. http://book.bionumbers.org/what-is-the-thickness-of-the-cell-membrane/ Eukaryotic cellular membranes are dynamic modificarse pueden - structures * se pueden formar vesiculas. (budding) https://news.mit.edu/2007/blood Figure 10-2  THE LIPID BILAYER Lipid Bilayer Responsible for the physical characteristics of membranes okigenos > - Amphipathic molecule More than 1000 different lipid species in eukaryote membranes Major Lipids in Cell Membranes Phosphoglycerides*** - most common Sphingolipids (sphingomyelin) Sterols Cholestera) FIGURE 2-13  The Lipid Bilayer: Composition and Structural Organization Membranes ̶ barriers between aqueous compartments Amphipathic phospholipids spontaneously form bilayers with hydrophilic faces and a hydrophobic core. Biological membranes vary in lipid composition impermeable to water-soluble molecules and ions have a viscous consistency with fluidlike properties Amphipathic phospholipids spontaneously form bilayers is with hydrophilic faces and a hydrophobic core. Elizaport Detergentes Jabonan aest sucio ~ net ar ↳ No se ve en la naturaleza Figure 10-3  Formation and study of pure phospholipid bilayers ethand + 2 cloroforms Figure 10-4 The faces of cellular membranes ic astoplasmic exoplasmic liumen) Cellular membranes have cytoplasmic and exoplasm leaflets ! organelos tambien tienen esto > Los - da para el lumen Centro · pare exoplasmica all organelo. Cytoplasmic exoplasmic -> rafelt ↑ endocytosis Figure 10-5 The faces of cellular membranes are conserved during membrane budding and fusion Figure 10-6 Variation in biomembranes in different cell types. Natural membranes from different cell types exhibit a variety of shapes, required for normal cell function. de celula tiene A Cada tipo una composicion de membrana es distinta. Figure 10-7  Main classes of ↳ Los en mas abundantes la membrana Phosphatidyine membrane lipids zesteronds phospatidylcholine phosphatidylserine Typical biomembrane: SM , PC * disminuyen e exoplasmic leaflet mich Composed of three classes of Fluidez PE , PS , PI - cytosolic Lo phosphatidyl nat let ever ond * aumentan inositol fluidez amphipathic lipids: Phosphoglycerides Yester Sphingolipids (animal) Sterols · cholesterol ergoster (fungi) Mideda · (plants · stigmasterl These lipids differ in structure, Glucosyl creprosides abundance, and function. Figure 10-8  * aen el a a Phosphoglycerides negativa interior. estar e · a g ↳ phospholipids Most abundant Glycerol backbone Tails – two esterified hydrophobic fatty acyl chains vary in length commonly 16 or 18 C vary in saturation saturada son solidas a Grasas Head – a polar group esterified * temperatura ambiente. dobles enlaces contiene to the phosphate ↑ son liquidas a insaturadas 4 major head groups * Grasas ambiente. temperatura PE = phosphatidylethanolamine PC = phosphatidylcholine Iheart , brain) PS = phosphatidylserine PI = phosphatidylinositol Figure 10-8  Fatty acid tails can differ in length and level of saturation Unbranched Length Level of saturation der waals menos van re bonds ↑ fluidez * Double : Fatty Acids That Predominate in Phospholipids  C=C bond stereoisomer configurations - esteroisomeros FIGURE 2-21  se crean cuando ↑ hidrolizan las fosfolipasas Lysophospholipids enlaces acido esteres y sacan. un graso. ↳ solo tienen una colita de acido graso. Synthesized by the action of phospholipases.hidroliza ↳ e en Functions: signaling, exoplasmic Leaflet membrane structure Ejemplo : O fosfolipasa > 2 & https://www.nature.com/articles/srep30336  P O R Plasmalogens R - 10 - - R - - ether ester ether * aster Ether bond – sn-1 position Ester bond - sn-2 position O - R - 0 Constitute 10 mol% of the total mass of phospholipids in humans Abundant in brain and heart Functions: Structural - organization and stability of lipid raft microdomains and cholesterol-rich membrane regions involved in c ellular signaling. Internal membrane antioxidant Synaptic transmission  Sphingolipids Derivatives of sphingosine sphingomyelin amino alcohol with a long ↑ hydrocarbon chain Various fatty acyl chains O connected by an> - amide bond nussons Sphingomyelins (SM) – contain a phosphocholine head group amida Some sphingolipids are glycolipids (GlcCer = Glucose-Ceramide) Figure 10-8  with ↳ sphingolipids head carponydrate groups Gangliosides and Cerebrosides en el ↳ comunes Sistema nervioso - glucolipids Sterols > 4 > - fused rings 3 cyclonexane > - I cyclopentance Figure 10-8  TABLE 10-1: Major Lipid Components of Selected Biomembranes Composition Composition Composition Composition (mol %): Source/Location (mol %): PC (mol %): PE + PS (mol %): SM Cholesterol Plasma membrane (human erythrocytes) 21 29 21 26 Myelin membrane (human neurons) 16 37 13 34 Plasma membrane (mung bean) 47 43 0 0 Inner mitochondrial membrane (cauliflower) 42 38 0 0 Outer mitochondrial membrane (cauliflower) 47 27 0 0 Plasma membrane (E. coli) 0 85 0 0 Endoplasmic reticulum membrane (rat) 60 25 3 7 Golgi membrane (rat) 51 26 8 13 Inner mitochondrial membrane (rat) 40 37 2 7 Outer mitochondrial membrane (rat) 54 31 2 11 Primary leaflet location Exoplasmic Cytosolic Exoplasmic Both cantidad de colesterd. * Neuronas tienen mayor * colesterol solo PC = phosphatidylcholine; PE = phosphatidylethanolamine; PS = phosphatidylserine, SM = sphingomyelin. esta en lo clula animal. Source: Data from S. E. Horvath and G. Daum, 2013, “Lipids of Mitochondria," Prog. Lipid Res. 52:590-614.  Effect of lipid composition on bilayer thickness and curvature. anelos Lipid composition: ↳ lumen de Differs in exoplasmic and cytosolic leaflets Influences bilayer thickness – influences membrane protein distribution (a) Pure sphingomyelin (SM) bilayer: Thicker than phosphoglyceride (phosphatidylcholine) bilayer Cholesterol lipid-ordering effect increases phosphoglyceride bilayer thickness. [Lipid rafts are thicker than other membrane regions.] (b) Phospholipids: re mayormentepasa PC cylindrical shape – forms essentially flat monolayers PE conical shape (smaller head group) – forms curved monolayers (c) Bilayer enriched with PC in the exoplasmic leaflet and with PE in the cytosolic face (as in many plasma membranes) – natural curvature Annexin Several proteins can curve a membrane by binding to a phospholipid bilayer surface – important in formation of transport vesicles that maymentoFigure 10-11 at bud from a donor membrane.  Lipid Composition Influences the Physical Properties of Membranes Charge distribution influences protein structure and thus function cytosolic - leaflet > - Lysophospholids also curvature inner monolayer contains gives. the negative charged phosphoglicerides: PI and PS Figure 10-11 The uneven distribution between the two lipid mono- layers generates membrane asymmetry Asymmetrical distribution of phospholipids and glycolipids in the PM of RBCs  Cholesterol > - Available in animal ukaryotic Cells Is the most abundant lipid in the plasma membrane of animal cells. ~35-45% mol% of the total lipids Cholesterol and other sterols have a planar structure and intercalate between the acyl chains. “sterols provide structural support to membranes, preventing too close a packing of the phospholipids’ acyl chains to maintain a significant measure of membrane fluidity and at the same time conferring the necessary rigidity required for mechanical support.” (page 449)  estabilizador ! Cholesterol > - Efecto > ‘Decreases fluidity of lipid bilayers containing phospholipids with unsaturated fatty acyl chains and fluidizes bilayers of disaturated phospholipids and sphingolipids.’  Cholesterol Functions: Cellular Membranes Provides structural support Affects fluidity Affects permeability - emulsifier Precursor of bile acids produced the liver in stored in gallbladder the Precursor of steroid hormones ↳ estrogen Precursors of Vitamin D progesterone testosterone https://ib.bioninja.com.au/standard-level/topic-1-cell-biology/13-membrane- structure/cholesterol.html CHOL in Lipid Bilayers Can Form Domains of Different Compositions rafts lipid & 1:1 PC/SM 1:1:1 PC/SM/CHOL  Computer model of synthetic lipid bilayers Very disordered Hydration shell Essential Cell Biology, Fifth Edition Copyright © 2019 W. W. Norton & Company  Most Lipids and Many Proteins Are Laterally Mobile in Biomembranes Lipid Bilayer is a 2- dimensional fluid Rotation Lateral diffusion  ~> Se hace en proteinas y lipidos Fluorescence recovery after photobleaching (FRAP) experiments can quantify the large-scale lateral movement of proteins and lipids within the plasma membrane. fRAP A puede Utilizar se proteinas. para lipidos y * cura mas * A mayor alta ; mayor Fluorescencia ; fwidez ! mayor movimiento rateral (mayor. finidez) Figure 10-10  Lateral diffusion in cells.. 205 eukaryotic IS prokaryotic 1 sec 20 sec FIGURE 1-12 FIGURE 1-13  Gel-like and fluidlike forms of the phospholipid bilayer. Most lipids and many proteins are laterally mobile in biomembranes. Lipid molecule movement in membrane: Exchanges places with neighbors in a leaflet ~107 times/sec. Lateral diffusion – several micrometers per second. (Diffusion rates indicate bilayer is 100 times more viscous than water – ~olive oil viscosity.) Flip from leaflet to leaflet rarely – high energetic barrier to moving hydrophilic head through membrane hydrophobic core - una enzima : > Requiere de flipasa, flopasa (Top) Gel-to-fluid transition: * Phospholipids with long saturated fatty acyl chains assemble into a highly ordered, gel-like bilayer that maximizes hydrophobic interactions between tails. Heat – disorders nonpolar tails – induces a transition from a gel to a fluid within a temperature range of only a few degrees (phase transition temperature). Chain disorder decreases bilayer thickness. Figure 10-9 (Bottom) Molecular models of phospholipid monolayers in gel-like and fluidlike states – determined by molecular dynamics calculations.  Major Lipid Components of Selected Biomembranes Different membranes have different lipid compositions. Lipid composition influences the physical properties of membranes. Bilayer fluidity: Depends on lipid composition, structure of the phospholipid hydrophobic tails, and temperature Gel-like state: Van der Waals interactions and the hydrophobic effect cause the nonpolar tails of phospholipids to aggregate. Favored by longer, more saturated fatty acyl chains that pack tightly together. More fluid state: Phospholipids with short fatty acyl chains form fewer van der Waals interactions. Cis-unsaturation forms kinks in fatty acyl chains; kinked tails form fewer and less stable van der Waals interactions with other lipids. Cholesterol: Maintains appropriate fluidity of natural membranes essential for normal cell growth and reproduction Restricts random movement of phospholipid head groups at the outer surfaces of the leaflets – forms lipid rafts Steroid ring interaction with the long hydrophobic tails of phospholipids immobilizes lipids and decreases biomembrane fluidity. Membrane synthesis: Phospholipid distribution asymmetry reflects where lipids are synthesized in the endoplasmic reticulum and Golgi. Sphingomyelin is synthesized on the luminal (exoplasmic) face of the Golgi, which becomes the exoplasmic face of the plasma membrane. Phosphoglycerides are synthesized on the ER cytosolic face. Flippases can use ATP energy to flip phospholipids between leaflets.  SPT - phospholipids Experimental demonstration that diffusion of phospholipids within the plasma membrane is confined  Phospholipid diffusion is restricted within the bilayer (~0.5um)  Phospholipids are confined for very brief periods to certain areas and then hop from one confined area to another.  Motion is restricted by rows of membrane proteins bound to the membrane skeleton by their cytoplasmic domains.  The Fluidity of a Lipid Bilayer Depends on Its - Desorden en la membrand causa mas Composition and Temperature que sea is flaquita. ambiente a composin cambia Sel * FLUID VISCOUS Low High temperature temperature Long fatty acid Short fatty acid chains chains Saturated fatty Unsaturated acid chains fatty acid chains (melting temperature) What is the effect of chain length?  Saturated and long chain fatty acids have high melting points la TM. * Cholesterol no afecta Cholesterol and membrane Tm Cholesterol prevents phase shifts in the membrane Summary: The Fluidity of a Lipid Bilayer Depends on Its Composition and its Temperature · satuados  Homeoviscous adaptation – Organisms (mainly poikilotherms) maintain membrane fluidity as temperature changes by altering the composition of membrane lipids. – Remodeling lipid bilayers involves … ? · mas acidosgrasos insaturados/saturados · mas/menos colesterd Organisms may regulate membrane fluidity by changing lipid composition -fiebre afecte as proteina Y Lipid droplets form by budding and scission from the ER membrane. Cells store excess lipids in lipid droplets: Storage compartments for triglycerides and cholesterol esters – also may serve as platforms for storage of proteins targeted for degradation. Lipid droplet formation: Cholesterol esters and triglycerides accumulate within the hydrophobic core of the lipid bilayer. Delamination of the two lipid monolayers forms a “lens.” Lens growth creates a spherical droplet – released by scission at the neck. The newly formed droplet is surrounded by a lipid monolayer derived from the cytosolic leaflet of the ER Figure 10-13 membrane.  KEY CONCEPTS OF SECTION 10.1 The Lipid Bilayer: Composition and Structural Organization Membranes are crucial to cell structure and function. The eukaryotic cell is demarcated from the external environment by the plasma membrane and organized into membrane-limited subcompartments (organelles and vesicles). The phospholipid bilayer, the basic structural unit of all biomembranes, is a lipid sheet two molecules thick, with hydrophilic faces and a hydrophobic core that is impermeable to water-soluble molecules and ions. Proteins embedded in the bilayer endow the membrane with specific functions. Phospholipids spontaneously form bilayers and sealed compartments surrounding an aqueous space. As bilayers, all biological membranes have an internal (cytosolic) face and an external (exoplasmic) face. Some organelles are surrounded by two, rather than one, membrane bilayers. The primary lipid components of biomembranes are phosphoglycerides, sphingolipids, and sterols such as cholesterol. The term “phospholipid” applies to any amphipathic lipid molecule with a fatty acyl hydrocarbon tail and a phosphate-based polar head group.  KEY CONCEPTS OF SECTION 10.1, CONT. Biomembranes can undergo phase transitions from fluidlike to gel-like states depending on the temperature and the composition of the membrane. Most lipids and many proteins are laterally mobile in biomembranes. Different cellular membranes vary in lipid composition. Phospholipids and sphingolipids are asymmetrically distributed in the two leaflets of the bilayer, whereas cholesterol is fairly evenly distributed in both leaflets. Natural biomembranes generally have a viscous consistency with fluidlike properties. In general, membrane fluidity is decreased by sphingolipids and cholesterol and increased by phosphoglycerides. The lipid composition of a membrane also influences its thickness and curvature. Lipid rafts are microdomains containing cholesterol, sphingolipids, and certain membrane proteins that form in the plane of the bilayer. These lipid-protein aggregates might facilitate signaling by certain plasma- membrane receptors. - ER cytosolic monolayer. Lipid droplets are storage vesicles for lipids, originating in the ER. Biología de la Célula – Biol 4350 Dra. Clara Camacho Molecular Cell Biology, 9th Edition, 2021 Harvey Lodish; Arnold Berk; Chris A. Kaiser; Monty Krieger; Anthony Bretscher; Hidde Ploegh; Kelsey C. Martin; Michael Yaffe; Angelika Amon Macmillan Learning CELL THEORY AND THE STRUCTURE AND FUNCTION OF CELLS  Objetivos específicos de aprendizaje Al finalizar el tema, se espera que puedas: 1. Mencionar los postulados básicos de la teoría celular. 2. Reconocer las contribuciones de científicos clave en el desarrollo de la teoría celular, como Robert Hooke, Matthias Schleiden, Theodor Schwann y Rudolf Virchow. 3. Analizar cómo la tecnología y la observación microscópica han influido en la evolución de la teoría celular a lo largo del tiempo. 4. Reconocer la importancia de la teoría celular en el campo de la biología y su impacto en la comprensión de los organismos vivos. 5. Enumerar las características comunes a todas las células y las diferencias entre células procariotas y eucariotas. 6. Describir la función de los organelos celulares. 7. Desarrollar habilidades de pensamiento crítico al cuestionar y evaluar información relacionada con la teoría celular. ¿Cuáles son los temas de la biología celular que te interesan más?  Cell Biology is the study of cells; their structure, function, and behavior. Cell Biology can help us understand: What is life? What is the origin of life? Where did cells come from? How is that cells are similar to and yet different from each other? Why do we get sick, grow old and die? Cell Biology is an integrative science Time line – 1660s - Cells exist (van Leeuwenhoek and Hooke) cells come from pre-existing cells – 1830s - Cell theory life · basic unit of are the · cells cells · All organisms are composed of Schleiden, Schwann and Virchow – 1940s - Biochemistry of cells Techniques – Cytology Optical techniques – Biochemistry Ultracentrifugation – Cell fractionation Chromatography Electrophoresis – Genetics Heredity The genetic material is DNA  Robert Hooke (1635-1703) Published Micrographia in 1665. Using a compound microscope (30x), described chambers in thin slices of cork; called them cells (cellulae) since they reminded him of cells (small rooms) occupied by monks living in a monastery.  Antonie van Leeuwenhoek (1632-1723) Discovered bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells, microscopic nematodes …(working between 1670s-1680s) Simple microscope (~300x)  Robert Brown (1773-1858) ~1833 Studied the epidermis of orchids Discovered "an opaque spot," which he named the nucleus. Image obtained with the microscope of Robert Brown of a Cymbidium epidermis.  Matthias Schleiden (1804- 1881) German botanist established the importance of the nucleus in the function of a cell. Theodor Schwann (1810-1882) German physiologist Stated that all animals are made of cells and concluded that plants & animals are similar structures. Rudolph Virchow (1821-1902) 1859- Rudolph Virchow proposed that cells can only arise from previously existing cells. "Omnis cellula e cellula"... from ↳ cells come pre-existing cells. https://www.aaas.org/rudolph-virchow- father-cellular-pathology  los seres viros estan compuestos > Todos - de culas ↑ The Cell Theory: All living organisms are composed of cells. The cell is the basic unit of life. Cells arise from pre-existing cells. Theodor Schwann (1810–1822), Matthias Schleiden (1804– 1881), and Rudolph Virchow (1821– 1902).  Basidiomycota Dikaryotic Mycelium Syncytium – multinucleated cells  Examples in humans Multinucleated DIS : Striated muscle fibers Hepatocytes Osteoclasts ……  Nervous system Camillo Golgi drawings of neurons. Origin of the first cells  The Cell Theory: All living organisms are composed of cells. The cell is the basic unit of life. Cells arise from pre-existing cells. Theodor Schwann (1810–1822), Matthias Schleiden (1804– 1881), and Rudolph Virchow (1821–1902).  Cells come in an astounding assortment of shapes and sizes.  All living organisms descended from a commonbancestral cell. single-celled 3 dominios : celled single anism - e Procariotas ( Bacterias) > - org > - Archaea > - Eucariotas Living systems such as the human body consist of closely interrelated elements.  Molecules, Cells, and Model Organisms Biological systems follow the rules of chemistry and physics, but biological structures and processes have evolved along different paths under the pressures of natural selection for billions of years. Although highly diverged, all biological systems are composed of cells containing the same types of chemical molecules and employing similar principles of organization at the cellular level. Similarities across biological systems make investigations of model organisms informative for understanding fundamental cellular processes. Many eukaryotic organisms used in cell biology research have advantages for certain types of studies. in amen nene Yeasts Are Used to Study Fundamental Aspects of Eukaryotic Cell Structure and Function ame no were Haploid yeast cells carrying temperature-sensitive lethal mutations can be maintained at permissive temperature and analyzed at nonpermissive temperature roname  REPASO Estructura y Función de Células * Prokaryotes does not contain antes envolturd -1 cells membrane-bound organelles. wall > - smallern eukaryotic all nbosomes · They only Y organelle contain * only ribosomes. nucleoid regionhave comet awes noteus turned > - pudiered  Células Procarióticas Eucarióticas ¿Qué tienen en común? Membrana plasmática Citosol ↳ DNA Cromosomas Ribosomas  antes nucleo mm Células procarióticas [pro = antes; karyon = grano (núcleo)] Incluye bacterias y arqueobacterias.  Figure 7.4x2 E. coli No tienen núcleo ni organelos membranosos. Su material genético se encuentra en una región nucleoide. stranded - circular double membrane W * Hacen la respiracion celular en el plasma membrane. haun > - Las cyanobacterias toto sintesis.  Células eucarióticas [eu= verdadero; karyon = grano (núcleo)] Protistas, hongos, plantas y animales. Núcleo y organelos membranosos.  THE CELL is composed of Cell membrane Nucleus Cytoplasm Membranous Non membranous Protein Cytosol organelles organelles fibers Mitochondria Ribosomes Cytoskeleton and or chloroplasts Endoplasmic reticulum Golgi apparatus Lysosomes Peroxisomes Extracellular fluid  Citosol fluid. ↳ Gel-like * contiene 3 lisosomas. in b only animal limen acdico all peroxisomas nucleolo T compuestaaosa por ↑ contiene cell wall &. y plasmodesmata parecido a * contient · los gap & vacuola I junctions en iones , cloroplastos. funcion no en perso is ↳ se utiliza para estructura agament fotosintesis. ·3 aem basmode ↑ sinterizar predalimento  > - proteinas tostolipidos Membrana Plasmática > - > - > - cansohidratos conster Fibers of extracellular matrix (ECM) "" signaling Glyco- Carbohydrate protein Glycolipid EXTRACELLULAR SIDE OF MEMBRANE redals Cholesterol Microfilaments Peripheral of cytoskeleton proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE  Citoesqueleto Funciones:  Sostén estructural, movimiento y regulación de procesos celulares. El citoesqueleto está compuesto principalmente por tres tipos de fibras: segregation de rechromosome de polimeros  Microtúbulos Hecho > - tubulina de polimeros  Microfilamentos Hecho de - activa.  Filamentos Intermedios ↳ cytokinesis  microfilamentos Hechos > - de tubulina X-tubulina jB-tubulina contraccion muscular chromosome & > - cytokinesis segugation > estructuras - de anclaje cilia y flagella al componen de microtubulos. · son e como,que saca ca mucosidad del sistema respiratorio.  ↑ no todoslos organosmembranales a on e Núcleo y Sistema de Endomembranas * corpasuntManage a Sistema de endomembranas Relación puede ser  directa mediante continuidad física entre una membrana y otra  indirecta mediante vesículas que salen de una y se funden con otra Los miembros del sistema endomembranal son:  envoltura nuclear  retículo endoplásmico  aparato o complejo de Golgi  lisosomas Al * NO  vacuolas incluye  peroxisomas mitocondria ni  vesiculas coroplastos.  membrana plasmática  > EVNA - Núcleo y nucleolo heterochromatine densely packed; no transcription 6 > loosely enchromaten - packed ; yes transcription und contieneand memba cromatina = DNA + proteina membrane is * outer nuclear PER. > es - continua continuous to con ER T  encuentran en el citosol E se Ribosomas y RER CrRNA + proteinas) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. vieneas Tenesom -ribosIt si ⑮S d Pyr Nuclear Nucleolus Nucleus envelope Rough ER Smooth ER Nucleus 00.11µm m Ribosomes ER lumen Cisternae Rough ER Smooth ER Mitochondrion P rotein · Synthesis · lipid synthesis · ATP production · Hormones detoxification © Dennis Kunkel Microscopy, Inc/Phototake · · Neurotransmitters · cast · carbohydrate metabolism  Retículo endoplásmico liso (SER) Higado contiene mucho Smooth ER  Funciones:. Sintetiza lípidos Metabolismo de algunos carbohidratos Detoxifica drogas y venenos Almacena iones de calcio (Ca++)  a > - Grandescantid Hepatocito O  E Golgi complex  El aparato o complejo de Golgi  Recibe vesículas provenientes del retículo endoplásmico.  Modifica, almacena, sortea, empaca y envía hacia otras partes dentro de la célula o a la superficie de la misma.  Sintetiza algunas macromoléculas.  Polisacaridos   Lisosomas ↳ only in the animal cell.  Compartimientos digestivos : W  contienen enzimas hidrolíticas · 5) &  ambiente ácido. (pH - - * 2- class proteins pumps - and chloride channels ce permited acido en su lumen. ser ↳ endocytosis  cell  Vacuolas > - plant  Alimentaria  Contráctil  Central  Peroxisomas catalasas. ↳ contiene enzimas oxidasas y W b catabolismo Premature peroxisome Mature peroxisome convierten en de acidos H202 82 - grasos. Hz Y Division ER 0.25 µm  Están rodeados por una sola membrana.  Se encuentran en casi todas las células eucarióticas.  Tienen dos tipos de enzimas: oxidasas y catalasa.  Reacciones químicas  hidrólisis de ácidos grasos  detoxificación de alcohol y otros compuestos Otros organelos membranosos  Cloroplastos y mitocondrias: principales transformadores energéticos de la célula ↳ del No son parte Sistema endomembranal. Mitocondrias y Animal cell Cloroplastos Mitochondrion cells ↳ aerobic. Chloroplast Plant cell  Endomembrane system Nucleus 1. Nuclear envelope Location of most of the genCoopmyrigeht © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Endoplasmic Boundary that surrounds the nucleus reticulum Gene regulation Protein secretion and sorting Organization and protection of Glycosylation chromosomes via the nuclear matrix Lipid synthesis Metabolic functions and accumulation of Ca2+ 3. Golgi apparatus Protein secretion and sorting Glycosylation 4. Lysosome/vacuoles Degradation of organic molecules Storage of organic molecules Accumulation of water (plant vacuoles) 5. Peroxisomes Breakdown of toxic molecules such as H2O2 Breakdown and synthesis of organic molecules 6. Plasma membrane Uptake and excretion of ions and molecules Cell signaling Cell adhesion Semiautonomous organelles 1. Mitochondria Synthesis of ATP Cytosol Synthesis and modification of Coordination of responses to other organic molecules the environment Production of heat Coordination of metabolism 1. Chloroplasts (plants and algae) Synthesis of the proteome Photosynthesis Organization and movement via cytoskeleton and motor proteins