The nucleus Houses most of the cell s genetic material Controls gene expression Site of transcription RNA synthesis using DNA as a template Site of DNA synthesis replication Site of ribosome subunit assembly nucleolus Nucleus Nucleolus Nucleus nuclear envelope 4 8 Nucleus Nuclear envelope Outer membrane Inner membrane Chromatin DNA protein Cytoplasm Nuclear pore Nucleolus Synthesis of ribosomal subunit Nucleus 150 nm Nuclear pore complex Regulates export import of proteins RNA Flow of genetic information in the cell DNA 1 Synthesis of mRNA mRNA NUCLEUS 2 mRNA export to cytoplasm CYTOSOL mRNA Ribosome 3 Protein synthesis Polypeptide Amino acids Ribosomes 4 8 4 9 Ribosomes Protein synthesis machines Consist of two subunits large and small each composed of many different proteins ribosomal proteins and ribosomal RNA rRNA Subunits are assembled separately in nucleolus exported through nuclear pores to cytosol come together in cytosol to initiate translation Nucleolus Synthesis of ribosomal subun Free and bound ribosomes 4 6 4 7 Ribosomes carry out protein synthesis in two cytoplasmic locations In the cytosol free ribosomes On the surface of the endoplasmic reticulum ER bound ribosomes Free ribosomes in cytosol Ribosomes bound to endoplasmic reticulum Rough ER 0 1 m EM showing ER and ribosomes http medcell med yale edu histology cell lab php Destinations of proteins synthesized on free and bound ribosomes Ribosomes initiate protein synthesis in the cytosol Free ribosomes Bound ribosomes No targeting signal targeting signal Central vacuole http www mun ca biology desmid brian BIOL2060 BIOL2060 22 CB22 html Endomembrane System a system of membranous compartments connected either directly or indirectly by movement of vesicles Bound ribosomes Endoplasmic Reticulum http www sumanasinc com webc ontent animations content vesi clebudding html Nuclear envelope Golgi Lysosomes animals Vacuole Central Vacuole plants Plasma membrane or cell exterior Endomembrane protein transport http youtu be SGBiy1HlWH8 Protein flow through the endomembrane system 4 12 Rough ER Vesicle containing proteins buds from the rough ER diffuses through the cell 1 and fuses with the Golgi apparatus The proteins are modified and packaged into vesicles for transport to their final destinations Transport vesicle Golgi Apparatus Membrane protein 2 The vesicle may travel to the plasma membrane releasing 3 its contents to the extracellular environment Secretory vesicle Plasma membrane Cell Secreted exterior protein Rough ER functions Synthesis of proteins destined for endomembrane compartments and for secretion cell exterior Protein modification Glycosylation addition of small polysaccharide to polypeptide creates glycoprotein e g basis of ABO blood groups Golgi functions cellular distribution center Sorts and packages materials into transport vesicles Modifies proteins received from the ER Manufactures some macromolecules e g some plant cell wall polysaccharides Endomembrane compartments and destinations Bound ribosomes Nuclear envelope Endoplasmic Reticulum Golgi Lysosomes animals Vacuole Central Vacuole plants Plasma membrane or cell exterior Lysosomes Digestive Compartments Function in breakdown hydrolysis of all kinds of macromolecules Contain hydrolytic enzymes Two major modes of breakdown Phagocytosis Autophagy Lysosomes Phagocytosis Autophagy http youtu be ekdIEpSf 1I Phagocytosis 4 13 Phagocytosis uptake and lysosome mediated digestion of food particles bacteria viruses and other foreign particles Lysosome contains active hydrolytic enzymes Food vacuole fuses with lysosome Hydrolytic enzymes digest food particles Autophagy 4 13 Autophagy lysosome mediated degradation of cellular contents Mitochondrion http www helsinki fi bioscience biochemistry eskelinen Summary the endomembrane system provides a continuous flow of proteins membrane material and other macromolecules by movement of vesicles between various compartments in the cell Examples Hormones insulin Antibodies Hydrolytic enzymes Central vacuole Fluorescence microscopy of cytoskeleton The cytoskeleton network of protein fibers extending throughout the cell pg 66 Components of the Cytoskeleton pg 83 Three main types of protein fibers make up the cytoskeleton 7 nm Actin filament 25 nm Microtubule 10 nm Intermediate filament Microtubules and the mitotic spindle Microtubules Chromosomes 10 10 10 11 Mitotic spindle http www youtube com watch v 2J65DoinDKU Flagella and cilia 4 22 Amoeboid movement http www youtube com watch v PsYpngBG394