Chap 3-2 Cell Organelles 2024-2025 PDF

Chap 3-2 : Cell Organelles Professor : Aboussaouira Module : Cell Biology & Biomol 1/2 Module : Cell Biology Chapter : 4 Semest...

Chap 3-2 : Cell Organelles Professor : Aboussaouira Module : Cell Biology & Biomol 1/2 Module : Cell Biology Chapter : 4 Semester: 1 Academic year : 2024-2025 1 www.um6ss.ma  3 Organelle groupes According to their functions : 1. Endomembrane system : Endoplasmic reticulum + Golgi Apparatus + Vesicles Synthesis, molecules complexation, packaging & secretion 2. Mitochondria : ATP production / cell respiratory 3. Peroxisome : vesicules / cell epuration (H2O2, …) 2 ENDOMEMBRANE SYSTEM 3  ENDOMEMBRANE SYSTEM = ER + GA + Vesicles Synthesis, Complexation, Packaging and molecules secretion of Proteins & lipids Secretion : ER => GA => Vesicles=> => cell membrane (exocytosis vesicles) From nuclear membrane to cell membrane video in youtube : Harvard cell animation 4  Endoplasmic Reticulum Network of membrans + cavities (= citernae) in t cytosol with Flattened (RER) or tubular (SER) citernae Roads of cell secretions 2 ER types : Rough (RER, Ribosomes) and smooth (SER, No ribosome) 5  Ribosome - Cell organelle without membrane - Components : RNA + proteins - Present in cytoplasm, mitochondria, RER, nuclear mbne - Ensure RNA translation during protein synthesis 6  Endoplasmic Reticulum Functions Rôles physiologiques du RE video Harvard cell animation in website Synthesis and trafficking of Proteins (Failed proteins cross to cytosol & destroyed) N Glycosylation proteins (and lipids) Cell Detoxification of metabplic wastes 7 8  Protein synthesis and transfer in RER Synthesis begins with ER signal sequence (ER SS) Inhibition of polypeptide chain growing ER Signal Sequence recognized by SRP (Signal Recognition Particle) SRP pulls ERSS-mRNA-Ribosome complexe to SRP receptor in RE membrane Formation of Channel translocon in the RE membrane SRP detachement and recycling Recovery of polypeptide chain growing that cross into RER cavity by the translocon ; until stop codon Ribosome releases and channel closes on protein Cleavage of SS from the protein that transit to AG 9 Protein synthesis and transfer into RER 10  N glycosylation of proteins = Glucose fixation on N end protein at aspartic aminoacid position 11  Detoxification In SER of liver and kidney cells Concerns xenobiotics : medicine, drugs, pesticides, …. 2 Seps: 1. Xenobiotic hydroxylation (X + OH)=> xenobiotic oxide (XO) that diffuse via SER membrane into SER cavity 2. xenobiotic conjugation with glucoronate (glucoronic acid) by SER enzymes => xenobiotic neutalization 12  Detoxification scheme PM Xenobiotic (X) MDR pump X urine, bile X OX Glucoronate - OX SER 13 Golgi Apparatus 14 Golgi Apparatus in ENDOMEMBRANE SYSTEM ER buds vesicules that fuse and form GA 15  Golgi Apparatus Near the nucleus, = 20 dictyosma/cell, Dictyosoma : structure with curved and flattened Cisternae GA : Network of dictyosoma linked with peripheral tubules 16 Golgi Apparatus under TEM : 1 Dictyosome = 4-6 saccules (citernae) + vesicules Polarity : Cis face : convex or bombed face Trans face : concave 17  Golgi Functions - Receiving proteins from RER and lipids from SER - Proteins & lipids complexation (maturation) (+ 1 other molecule) - Cell centre Packaging : Vesicules formation by Buding mechanisma (1 molecule type/vesicule) - Secretion of hormones, proteins, lipids (exocytosis) 18  Lysosome - Sort of Golgi vesicles - Membrane lysosome = cell membrane - Into the lysosome cavity : Hydrolytic acidic enzymes with pH 3 to 5 (H+pump) => hydrolysis of large molecules (Cell Digestive Enzymes) => lysosome = cell stomach - 40 types of hydrolytic enzymes : Dnase, Rnase, Lipase, Protease, Osidases, Phospholipidase…… 19  Lysosome Functions Hydrolyse extracell substances (nutrients, germs) by Heterophagy and Intracellular molecules (Destroyed, old and non functional) by Autopaghy Sorting cellular small molecules resulting from the hydrolysis : Small molecule to cytosol Trash to cell membrane To Golgi (recomplexation : recycling molecules) To RE for re3D shape, reN glycosylation Fuse endosome to work 20  Endosome Endocytic vesicles fuse => Early endosome Others autophagic molecules and organelles join the early endosome => Late endosome Late endosome fuses with lysosome => Hydrolysis (after acidifiying its content by pumping H+ from the cytosl) Small Molecules resulting from the digestion are dispatching towards : Cytosol, Cell Membrane, Golgi A or Reticulum 21 22 ES in cell infected by Corona virus 23  Peroxisome Produce hydrogen peroxid Spheric vesicule with Membrane (like CM) and enzymes into the cavity (Catalase & Oxidases) Crystalline appearance due to catalase that crystallizes at 37°C Ensure oxidation of ipids & proteins producing hydrogen Peroxid (H2O2) by oxidases H2O2 elimination by catalase 24 Cell epuration : H2O2 production and elimination  Cell Epuration (Peroxisomal diseases) Oxydase Catalase RH2 + 02 ---------→ R + H2O2 2 H2O R'H2 R' RH2 : proteins and lipids R’H2 : anti oxydants (vitamins, carotene, lycopene, omega 3 acid) Without anti oxydants, H2O2 poduces free radical OH. that oxidates and inactivates cell biological molecules (DNA, proteins, lipids, carbohydrats) and damaged them => Peroxisomial diseases 25  EPURATION REACTIONS IN PEROXISOME Two steps : 1. Various metabolits (aa, ag, uric acid, …) produce H2O2 after degradation by oxidases (peroxidase, glutathione peroxidase ou GP, Superoxide Dismutase ou SOD ) oxidase RH2 + O2 → R + H2O2 These oxidations occur in the peroxisome where oxidases are located 2. Produced H2O2 is degradated in peroxisome depending on the reaction : catalase R’H2 + H2O2 → R’ + 2H2O R'H2 = anti oxydants 26 Anti oxydants action 27  Peroxisom Proliferators Agents (PPA) PPA induce a significant proliferation (up to 60x) of peroxisoms especially in the liver Ex of PPA : Aspirin, lipid-lowering, oral anti- diabetics like clofibrate 28 Others free radical sources: cell oxidative stress 29 30  Peroxisome Polymorphisme a et b : cells labeled with antibodies to catalase (rhodamin in red) and tubulin (fluorescein in green) a Spherical form of peroxisomes b Tubular form of peroxisomes op 10 High Antioxidant Foods - Rewire Me ntioxidant Food Chart oods Rich In Antioxidants: 10 Foods For Better Health - Fitelo 32 Mitochondria 33  Mitochondrial abnormalities Crests balls Crystallized crests Crests interwined 34 35  Mitochondria ▪ outer mb: permeable, CM-like (40% lip, 60% prot) ▪ Inner mb: limited permeability, 20% lipids, 80% prot (respiratory chain and ATPosomes) ▪ ATPosome or ATP synthase : Inner mb protein with several subunits and 3 domains : base, stem and spherical head with ATP synthetase ▪ Intermembrane space with the same composition as cytosol + adenylkinase (AK) which catalyze the reaction : AMP + ATP => 2 ADP 36  Matrix Composition Ribosomes : smaller than cytoplasmic ribosomes Substances : water, mineral salts, ATP, ADP, co-enzymes, cytochromes, nucleotides, nucleosides, RNA, pyruvic acid, bold, a. amine, O2 and CO2, HSp70 proteins Mitochondrial genome : circular DNA (16,000 bp), 5 to 10 by mitochondria Inherited from the mother Code for respiratory chain proteins, complexes III, IV and V (only -10% of them) 37  Mitochondria functions Energy production : cellular respiration Apoptosis Regulation of intracellular calcium Oxidation of fatty acids Synthesis of steroids 38  Cellular Respiratory : 4 phases In youtube : Electron transfert chain 1. Metabolit degradation (carbohydrats, lipids, protids) by glycolysis, lipolysis or proteolysis producing acetyl CoA 2. Kreb cycle : acetyl CoA oxidations and energetic electrons (e) extraction 3. Respiratory chain (e transfer) : e- oxido-reduction reactions & production of a little quantity of energy (e) that push H+ into tne intermembrane space => creation of H+ gradient 4. Oxidative phosphorylation : To equilibrate the gradient, H+ cross the ATPosome into mitochondrial matrix and creates a H+ flow => ATPosome base activation (likes turbine) => E production. ATP synthetase in ATPosome head catalyze reaction : ADP + P + E => ATP 40 41  ATPosome base turbine Matrix Membrane 42 Medical applications : Cell organelles & pathologies pathology 43