Role of Microtubules in the Distribution of the Golgi Apparatus
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Common Features of All Cells Bacterial
www.denniskunkel.com Tour of the Cell part 1 Today’s Topics • Finish Nucleic Acids Cells • Properties of all cells – Prokaryotes and Eukaryotes • Functions of Major Cellular Organelles – Information – Synthesis&Transport – Energy Conversion – Recycling – Structure and Movement Bacterial cell Animal Cell 9/12/12 (Prokaryote) (Eukaryote) 2 www.denniskunkel.com Common features of all cells • Plasma Membrane – defines inside from outside • Cytosol – Semifluid “inside” of the cell • DNA “chromosomes” - Genetic material – hereditary instructions • Ribosomes – “factories” to synthesize proteins 4 Plasma membrane Bacterial (Prokaryotic) Cell Ribosomes! Plasma membrane! Bacterial Cell wall! chromosome ! Phospholipid bilayer Proteins 0.5 !m! Flagella! No internal membranes 5 6 1 Figure 6.2b 1 cm Eukaryotic Cell Frog egg 1 mm Human egg 100 µm Most plant and animal cells 10 m µ Nucleus Most bacteria Light microscopy Mitochondrion 1 µm Super- 100 nm Smallest bacteria Viruses resolution microscopy Ribosomes 10 nm Electron microscopy Proteins Lipids 1 nm Small molecules Contains internal organelles 7 0.1 nm Atoms endoplasmicENDOPLASMIC RETICULUM reticulum (ER) ENDOPLASMIC RETICULUM (ER) NUCLEUS NUCLEUS Rough ER Smooth ER nucleus Rough ER Smooth ER Nucleus Plasma membrane Plasma membrane Centrosome Centrosome cytoskeletonCYTOSKELETON CYTOSKELETON Microfilaments You should Microfilaments Intermediate filaments know everything Intermediate filaments Microtubules in Fig 6.9 ribosomesRibosomes Microtubules Ribosomes cytosol GolgiGolgi apparatus apparatus Golgi apparatus Peroxisome Peroxisome In animal cells but not plant cells: In animal cells but not plant cells: Lysosome Lysosomes Lysosome Lysosomes Figure 6.9 Centrioles Figure 6.9 Centrioles Mitochondrion lysosome Flagella (in some plant 9sperm) Mitochondrion Flagella (in some plant10 sperm) mitochondrion Nuclear envelope Nucleus Nucleus 1 !m Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Pores Pore complex Rough ER Surface of nuclear envelope. -
Cytoplasmic Organelles
CYTOPLASMIC ORGANELLES OBJECTIVES: After completing this exercise, you should be able to: 1. Recognize features of the cytoplasm in the light microscope. 2. Identify major cellular organelles in electron micrographs. 3. Provide general functions of cellular organelles. ASSIGNMENT FOR TODAY'S LABORATORY GLASS SLIDES - https://medmicroscope.uc.edu/ SL 181 (spinal cord) rough endoplasmic reticulum SL 108 (pancreas) rough endoplasmic reticulum SL 125 (inflammation) rough endoplasmic reticulum and Golgi apparatus ELECTRON MICROGRAPHS (Gray envelope) EM 3-6, 4-5, 12-1, 16 plasma membrane EM 1-3, 2-1, 2-2, 3-5, 4-1, 10-5, 14-3 rough endoplasmic reticulum EM 4-2, 10-6, 12-3, 13-7, 14-5 smooth endoplasmic reticulum EM 5-2 and 5-inset ribosomes EM 11-1 to 11-4 Golgi apparatus EM 6-10 to 6-13, 2-3 to 2-5 also 3-4, 1-4, 12-2 and 13-6 mitochondria EM 3, 4, 16 and 17 Magnification and Resolution POSTED ELECTRON MICROGRAPHS # 1 Organelles # 6 Organelles Lab 2 Posted EMs SUPPLEMENTAL MATERIAL: SUPPLEMENTARY ELECTRON MICROGRAPHS Rhodin, J. A.G., An Atlas of Histology Plasma membrane Fig. 2-2; 2-3 Rough ER Fig 2-26; 2-29; 2-30; 2-31; 2-32 Smooth ER Fig 2-33; 2-34; 2-35 Ribosomes Fig 2-27; 2-28; 2-30; 2-31; 2-32 Golgi apparatus Fig 2-36; 2-37; 2-38 Mitochondria Fig 2-39; 2-40; 2-41 In the last lab, you were introduced to cells and extracellular matrix, followed by a focus on the nucleus. -
A Tour of the Cell Overview
Unit 3: The Cell Name______________________ Chapter 6: A Tour of the Cell Overview 6.1 Biologists use microscopes and the tools of biochemistry to study cells The discovery and early study of cells progressed with the invention of microscopes in 1590 and their improvement in the 17th century. In a light microscope (LM), visible light passes through the specimen and then through glass lenses. ○ The lenses refract light so that the image is magnified into the eye or a camera. Microscopes vary in magnification, resolution, and contrast. ○ Magnification is the ratio of an object’s image to its real size. A light microscope can magnify effectively to about 1,000 times the real size of a specimen. ○ Resolution is a measure of image clarity. It is the minimum distance two points can be separated and still be distinguished as two separate points. The minimum resolution of an LM is about 200 nanometers (nm), the size of a small bacterium. ○ Contrast accentuates differences in parts of the sample. It can be improved by staining or labeling of cell components so they stand out. Although an LM can resolve individual cells, it cannot resolve much of the internal anatomy, especially the organelles, membrane-enclosed structures within eukaryotic cells. The size range of cells 1 To resolve smaller structures, scientists use an electron microscope (EM), which focuses a beam of electrons through the specimen or onto its surface. ○ Theoretically, the resolution of a modern EM could reach 0.002 nm, but the practical limit is closer to about 2 nm. Scanning electron microscopes (SEMs) are useful for studying the surface structure or topography of a specimen. -
Phosphatases and Differentiation of the Golgi Apparatus
J. Cell Sci. 4, 455-497 (1969) 455 Printed in Great Britain PHOSPHATASES AND DIFFERENTIATION OF THE GOLGI APPARATUS MARIANNE DAUWALDER, W. G. WHALEY AND JOYCE E. KEPHART The Cell Research Institute, Tlie University of Texas at Austin, Texas, U.S.A. SUMMARY Cytochemical techniques for the electron microscopic localization of inosine diphosphatase, thiamine pyrophosphatase, and acid phosphatase have been applied to the developing root tip of Zea mays. Following formaldehyde fixation the Golgi apparatus of most of the cells showed reaction specificity for IDPase and TPPase. Following glutaraldehyde fixation marked localiza- tion of IDPase reactivity in the Golgi apparatus was limited to the root cap, the epidermis, and the phloem. A parallelism was apparent between the sequential morphological development of the apparatus for the secretion of a polysaccharide product, the fairly direct incorporation of tritiated glucose into the apparatus to become a component of this product and the develop- ment of the enzyme reactivity. Acid phosphatase, generally accepted as a lysosomal marker, was found in association with the Golgi apparatus in only a few cell types near the apex of the root. The localization was usually in a single cisterna at the face of the apparatus toward which the production of secretory vesicles builds up and associated regions of what may be smooth endoplasmic reticulum. Since the cell types involved were limited regions of the cap and epidermis and some initial cells, no functional correlates of the reactivity were apparent. Despite the presence of this lysosomal marker, no structures clearly identifiable as ' lysosomes' were found and the lack of reaction specificity in the vacuoles did not allow them to be so defined. -
Written Response #5
Written Response #5 • Draw and fill in the chart below about three different types of cells: Written Response #6-18 • In this true/false activity: • You and your partner will discuss the question, each of you will record your response and share your answer with the class. Be prepared to justify your answer. • You are allow to search answers. • You will be limited to 20 seconds per question. Written Response #6-18 6. The water-hating hydrophobic tails of the phospholipid bilayer face the outside of the cell membrane. 7. The cytoplasm essentially acts as a “skeleton” inside the cell. 8. Plant cells have special structures that are not found in animal cells, including a cell wall, a large central vacuole, and plastids. 9. Centrioles help organize chromosomes before cell division. 10. Ribosomes can be found attached to the endoplasmic reticulum. Written Response #6-18 11. ATP is made in the mitochondria. 12. Many of the biochemical reactions of the cell occur in the cytoplasm. 13. Animal cells have chloroplasts, organelles that capture light energy from the sun and use it to make food. 14. Small hydrophobic molecules can easily pass through the plasma membrane. 15. In cell-level organization, cells are not specialized for different functions. Written Response #6-18 16. Mitochondria contains its own DNA. 17. The plasma membrane is a single phospholipid layer that supports and protects a cell and controls what enters and leaves it. 18. The cytoskeleton is made from thread-like filaments and tubules. 3.2 HW 1. Describe the composition of the plasma membrane. -
Protein Export Via the Type III Secretion System of the Bacterial Flagellum
biomolecules Review Protein Export via the Type III Secretion System of the Bacterial Flagellum Manuel Halte and Marc Erhardt * Institute for Biology–Bacterial Physiology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany; [email protected] * Correspondence: [email protected] Abstract: The bacterial flagellum and the related virulence-associated injectisome system of pathogenic bacteria utilize a type III secretion system (T3SS) to export substrate proteins across the inner membrane in a proton motive force-dependent manner. The T3SS is composed of an export gate (FliPQR/FlhA/FlhB) located in the flagellar basal body and an associated soluble ATPase complex in the cytoplasm (FliHIJ). Here, we summarise recent insights into the structure, assembly and protein secretion mechanisms of the T3SS with a focus on energy transduction and protein transport across the cytoplasmic membrane. Keywords: bacterial flagellum; flagellar assembly; type III protein export; ATPase; proton motive force; secretion model 1. Introduction Flagella are complex rotary nanomachines embedded in the cell envelope of many Citation: Halte, M.; Erhardt, M. bacteria. In addition to functions in adhering to surfaces, flagella allow bacteria to move Protein Export via the Type III in their environment towards nutrients or to escape harmful molecules. They are present Secretion System of the Bacterial in both Gram-negative and Gram-positive bacteria, and are evolutionary related to the Flagellum. Biomolecules 2021, 11, 186. injectisome device, which various Gram-negative bacterial species use to inject effectors into https://doi.org/10.3390/ eukaryotic target cells [1]. Both the flagellum and injectisome are complex nanomachines biom11020186 and made of around 20 different proteins, ranging from a copy number of very few to several thousand [2]. -
A Study of Extracellular Space in Central Nervous Tissue by Freeze-Substitution
A STUDY OF EXTRACELLULAR SPACE IN CENTRAL NERVOUS TISSUE BY FREEZE-SUBSTITUTION A. VAN HARREVELD, M.D., JANE CROWELL, Ph.D., and S. K. MALHOTRA, D.Phil. From the Kerckhoff Laboratories of the Biological Sciences, California Institute of Technology, Pasadena, California ABSTRACT Downloaded from It was attempted to preserve the water distribution in central nervous tissue by rapid freezing followed by substitution fixation at low temperature. The vermis of the cerebellum of white mice was frozen by bringing it into contact with a polished silver mirror maintained at a temperature of about -207C. The tissue was subjected to substitution fixation in acetone containing 2 per cent Os0 4 at -85°C for 2 days, and then prepared for electron micros- copy by embedding in Maraglas, sectioning, and staining with lead citrate or uranyl www.jcb.org acetate and lead. Cerebellum frozen within 30 seconds of circulatory arrest was compared with cerebellum frozen after 8 minutes' asphyxiation. From impedance measurements under these conditions, it could be expected that in the former tissue the electrolyte and water distribution is similar to that in the normal, oxygenated cerebellum, whereas in the on August 22, 2006 asphyxiated tissue a transport of water and electrolytes into the intracellular compartment has taken place. Electron micrographs of tissue frozen shortly after circulatory arrest re- vealed the presence of an appreciable extracellular space between the axons of granular layer cells. Between glia, dendrites, and presynaptic endings the usual narrow clefts and even tight junctions were found. Also the synaptic cleft was of the usual width (250 to 300 A). -
Lysosome Trafficking Is Necessary for EGF-Driven Invasion and Is
Dykes et al. BMC Cancer (2017) 17:672 DOI 10.1186/s12885-017-3660-3 RESEARCH ARTICLE Open Access Lysosome trafficking is necessary for EGF- driven invasion and is regulated by p38 MAPK and Na+/H+ exchangers Samantha S. Dykes1,2,4, Joshua J. Steffan3* and James A. Cardelli1,2 Abstract Background: Tumor invasion through a basement membrane is one of the earliest steps in metastasis, and growth factors, such as Epidermal Growth Factor (EGF) and Hepatocyte Growth Factor (HGF), stimulate this process in a majority of solid tumors. Basement membrane breakdown is one of the hallmarks of invasion; therefore, tumor cells secrete a variety of proteases to aid in this process, including lysosomal proteases. Previous studies demonstrated that peripheral lysosome distribution coincides with the release of lysosomal cathepsins. Methods: Immunofluorescence microscopy, western blot, and 2D and 3D cell culture techniques were performed to evaluate the effects of EGF on lysosome trafficking and cell motility and invasion. Results: EGF-mediated lysosome trafficking, protease secretion, and invasion is regulated by the activity of p38 mitogen activated protein kinase (MAPK) and sodium hydrogen exchangers (NHEs). Interestingly, EGF stimulates anterograde lysosome trafficking through a different mechanism than previously reported for HGF, suggesting that there are redundant signaling pathways that control lysosome positioning and trafficking in tumor cells. Conclusions: These data suggest that EGF stimulation induces peripheral (anterograde) lysosome trafficking, which is critical for EGF-mediated invasion and protease release, through the activation of p38 MAPK and NHEs. Taken together, this report demonstrates that anterograde lysosome trafficking is necessary for EGF-mediated tumor invasion and begins to characterize the molecular mechanisms required for EGF-stimulated lysosome trafficking. -
Reconstructions of Centriole Formation and Ciliogenesis in Mammalian Lungs
J. Cell Sci. 3, 207-230 (1968) 207 Printed in Great Britain RECONSTRUCTIONS OF CENTRIOLE FORMATION AND CILIOGENESIS IN MAMMALIAN LUNGS S. P. SOROKIN Department of Anatomy, Harvard Medical School, Boston, Massachusetts 02115, U.S.A. SUMMARY This study presents reconstructions of the processes of centriolar formation and ciliogenesis based on evidence found in electron micrographs of tissues and organ cultures obtained chiefly from the lungs of foetal rats. A few observations on living cultures supplement the major findings. In this material, centrioles are generated by two pathways. Those centrioles that are destined to participate in forming the achromatic figure, or to sprout transitory, rudimentary (primary) cilia, arise directly off the walls of pre-existing centrioles. In pulmonary cells of all types this direct pathway operates during interphase. The daughter centrioles are first recognizable as annular structures (procentrioles) which lengthen into cylinders through acropetal deposition of osmiophilic material in the procentriolar walls. Triplet fibres develop in these walls from singlet and doublet fibres that first appear near the procentriolar bases and thereafter extend apically. When little more than half grown, the daughter centrioles are released into the cyto- plasm, where they complete their maturation. A parent centriole usually produces one daughter at a time. Exceptionally, up to 8 have been observed to develop simultaneously about 1 parent centriole. Primary cilia arise from directly produced centrioles in differentiating pulmonary cells of all types throughout the foetal period. In the bronchial epithelium they appear before the time when the ciliated border is generated. Fairly late in foetal life, centrioles destined to become kinetosomes in ciliated cells of the epithelium become assembled from masses of fibrogranular material located in the apical cytoplasm. -
Studies on the Mechanisms of Autophagy: Formation of the Autophagic Vacuole W
Studies on the Mechanisms of Autophagy: Formation of the Autophagic Vacuole W. A. Dunn, Jr. Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610 Abstract. Autophagic vacuoles form within 15 min of tophagic vacuoles. All these results suggested that au- perfusing a liver with amino acid-depleted medium. tophagic vacuoles were not formed from plasma mem- These vacuoles are bound by a "smooth" double mem- brane, Golgi apparatus, or endosome constituents. An- brane and do not contain acid phosphatase activity. In tisera prepared against integral membrane proteins (14, Downloaded from http://rupress.org/jcb/article-pdf/110/6/1923/1059547/1923.pdf by guest on 26 September 2021 an attempt to identify the membrane source of these 25, and 40 kD) of the RER was found to label the in- vacuoles, I have used morphological techniques com- ner and outer limiting membranes of almost all na- bined with immunological probes to localize specific scent autophagic vacuoles. In addition, ribophorin II membrane antigens to the limiting membranes of was identified at the limiting membranes of many na- newly formed or nascent autophagic vacuoles. Anti- scent autophagic vacuoles. Finally, secretory proteins, bodies to three integral membrane proteins of the rat serum albumin and alpha2o-globulin, were localized plasma membrane (CE9, HA4, and epidermal growth to the lumen of the RER and to the intramembrane factor receptor) and one of the Golgi apparatus space between the inner and outer membranes of some (sialyltransferase) did not label these vacuoles. Inter- of these vacuoles. The results were consistent with the nalized epidermal growth factor and its membrane formation of autophagic vacuoles from ribosome-free receptor were not found in nascent autophagic vacu- regions of the RER. -
Intracellular Transport in Eukaryotes
Intracellular transport in eukaryotes Overview Compartmentalization and inner membranes enables eukaryotic cells • to be 1000-10000 times larger than prokaryotes • to isolate specialized chemical processes in specific parts of the cell • to produce “packages” (vesicles) of chemical components that can be shuttled around the cell actively Membrane-enclosed organelles take up ~50% of the volume of eukaryotic cells: • nucleus – genomic function • endoplasmic reticulum – synthesis of lipids; on the border with the cytosol, synthesis of proteins destined for many organelles and the plasma membrane • Golgi apparatus – modification, sorting, and packaging of proteins and lipids for specific intracellular destination (akin to a mail sort facility) • lysosomes – degradation • endosomes – sorting of endocytosed (engulfed) material by the cell • peroxisomes – oxidation of toxic species • mitochondria , chloroplasts – energy conversion Cells contain ͥͤ ͥͦ protein molecules that are constantly being synthesized and 10 Ǝ 10 degraded Proteins are synthesized in the cytosol , but not all proteins remain there and many must be transported to the appropriate compartment For comparison: transport by diffusion Even without active transport requiring free energy transduction, movement of molecules in the cell is rapid by diffusive motion © M. S. Shell 2009 1/11 last modified 10/27/2010 Consider a sea of molecules. Pinpoint one molecule and note its starting position at time 0. Due to thermal motion, the particle on average makes a random jump of length every units ͠ of time. The jump is random in the radial direction. This is called a random walk . Repeat this process for many jumps n and interrogate the final distance of the particle from its starting point ͦ ͠ We could imagine doing many such experiments. -
Membrane Structure in Mammalian Astrocytes: a Review of Freeze-Fracture Studies on Adult, Developing, Reactive and Cultured Astrocytes
y. exp. Bid. (1981), 95. 35~48 35 JVith 6 figures 'Printed in Great Britain MEMBRANE STRUCTURE IN MAMMALIAN ASTROCYTES: A REVIEW OF FREEZE-FRACTURE STUDIES ON ADULT, DEVELOPING, REACTIVE AND CULTURED ASTROCYTES BY DENNIS M. D. LANDIS Department of Neurology, Massachusetts General Hospital, Boston, MA. 02114 AND THOMAS S. REESE Section on Functional Neuroanatomy, National Institute of Neurological and Communicative Diseases and Stroke, National Institutes of Health, Bethesda, MD. 20014 SUMMARY The application of freeze-fracture techniques to studies of brain structure has led to the recognition of two unsuspected specializations of membrane structure, each distributed in a specific pattern across the surface of astro- cytes. 'Assemblies' (aggregates of uniform, small particles packed in orthogonal array into rectangular or square aggregates) are found to characterize astrocytic plasma membranes apposed to blood vessels or to the cerebrospinal fluid at the surface of the brain. These particle aggregates are much less densely packed in astrocytic processes in brain parenchyma. Assemblies are not fixation artifacts, have been shown to extend to the true outer surface of the membrane, are remarkably labile in the setting of anoxia, and are at least in part protein. The function of assemblies is unknown, but their positioning suggests that they may have a role in the transport of some material into or out of the blood and cerebrospinal fluid compartments. A second specialization of intramembrane particle distri- bution, the polygonal particle junction, links astrocytic processes at the surface of the brain, and also links proximal, large caliber astrocytic processes in brain parenchyma. The function of this membrane specialization also is unknown, but it may subserve a mechanical role.