introduction to Intracellula compartments

Cell Biology Course Intracellula Compartments PhD Nguyen, Lai Thanh Dept of Cytoloty, Histology, Embyology and Biophysics Hanoi -11/03/2013 Objectives  Type of prokaryote intracellular compartments  Structure and function of ER, Golgi, Endosome, Lysosome, Peroxisome  Exocytosis, Endocytosis, and Phagocytosis Cellular Organelles  Cytoplasm of eukaryotic cells contain a network of interconnecting membranes These membranes enclose a lumen This extensive structure is called endoplasmic reticulum  It consists of membranes with smooth appearance in some areas and rough appearance in some areasSmooth endoplasmic reticulum and rough endoplasmic reticulum  In this lumen newly synthesized proteins are modified  Rough appearance is due to the presence of ribosomes attached on its outer side  These ribosomes are involved in the biosynthesis of proteins  These proteins are either incorporated into the membranes or into the organelles  Special proteins are present so called CHAPERONES Theses proteins play a role in proper folding of proteins  Protein glycosylation also occurs in ER, for example, the carbohydrates are attached to the newly synthesized proteins  Smooth endoplasmic reticulum is involved in lipid synthesis  Cholesterol synthesis  Steroid hormones synthesis  Detoxification of endogenous and exogenous substances  ER along with Golgi apparatus is involved in the synthesis of other organelles –lysosomes & Peroxisomes   Elongation of fatty acids Desaturation of fatty acids Exocytosis in TEM Three Pathways  Bulk-phase endocytosis  Extracellular fluid is captured in a vesicle and brought into the cell; the reverse of exocytosis  Receptor-mediated endocytosis  Specific molecules bind to surface receptors, which are then enclosed in an endocytic vesicle  Phagocytosis  Pseudopods engulf target particle and merge as a vesicle, which fuses with a lysosome in the cell Endocytosis Cellular components of the endocytic pathway lysosome plasma late membrane endosome nuclear envelope endoplasmic reticulum early endosome CYTOSOL cis Golgi trans Golgi stack Golgi network network Golgi apparatus Lysosomes and Endosomes  Early endosome   pH 6.5-6 sorting endosome  Late endosome  pH 5.5-5  Lysosome  pH 5-4.5 Phagocytosis – solid Pinocytosis – liquid (general) Endocytosis: Uptake of substances Transport of protein or lipid components of compartments Metabolic or division signaling Defense to microorganisms Predominant cells: Functions: unicellular cells macrophages osteoslats throphoblasts uptake of food partickles immuneresponses elimination of aged cells (RBC) Required: signal membrane receptor (Fc receptor for Ab) formation of pseudopodium cortical actin network The formed vesicle: phagosome (hetero-; auto-) Phagocytosis Receptor-Mediated Endocytosis Endosomes - pinch off from plasma membrane Clathrin -coated pits and vesicles  Tubulovesicular morphology   membrane concentrated tubules bud & recycled directly & indirectly Golgi apparatus Endosome ER Lysosome Original surface Thank You ! ... of prokaryote intracellular compartments  Structure and function of ER, Golgi, Endosome, Lysosome, Peroxisome  Exocytosis, Endocytosis, and Phagocytosis Cellular Organelles  Cytoplasm of eukaryotic... contents to the surroundings  Endocytosis (into the cell)  The formation of a vesicle from cell membrane, enclosing materials near the cell surface and bringing them into the cell Exocytotic processes... membrane proteins move to the Golgi, a series of membrane-bound compartments found near the nucleus Golgi nucleus  Enzymes in golgi complex transfer carbohydrate units to proteins to form of glycoporoteins,