DOCSLIB.ORG

Plant & Animal Cells and Their Organelles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Plant & Animal Cells and Their Organelles Cells and Their Organelles The cell is the basic unit of life. All cells are surrounded by a cell membrane (which is sometimes called a plasma membrane). The cell membrane is semipermeable, meaning it allows some substances to pass into the cell and blocks others out. Plant cells have an additional layer surrounding them called the cell wall. The cell wall is made of nonliving material called cellulose. The centriole (also called the "microtubule organizing center") is a small body located near the nucleus. The centriole is where microtubules are made. During cell division (mitosis), the centriole divides and the two parts move to opposite sides of the dividing cell. Only animal cells have centrosomes. Microtubules are shaped like soda straws and give the nucleus and cell its shape (like a skeleton gives you shape) Answer the questions after each reading section on your own paper, please! 1. What is the basic unit of living things? 2. What surrounds all cells? 3. What is meant by semipermeable? 4. What additional layer is found around the outside of plant cells? 5. Cell walls in plants are made up of C_ ___ ___ ___ ___ ___ ___ ___ ___. 6. Centrioles are found inside of what type of cell only? 7. Microtubules have what shape and do what jobs for the cell? __________________________________________________________________________________________ The nucleus (in the center of a cell) is a rounded body containing the nucleolus and a cell’s DNA. The nucleus controls most of the functions of the cell by controlling protein synthesis. The nucleus of plant and animal cells is surrounded by the nuclear membrane. Materials can move from the nucleus to the cytoplasm through nuclear pores in the membrane around the nucleus. Cytoplasm is the jellylike material outside the cell nucleus in which the cell’s organelles are located. All cells, even prokaryotes, contain small bodies called ribosomes. Proteins are made in the ribosomes by a process called protein synthesis. 8. Where is DNA found inside a cell? 9. What cell process is controlled by the nucleus? 10. Where are organelles located? 11. Do all cells need ribosomes? 12. Where are proteins made in a cell? 13. The process of making proteins is called ________________ ______________________. 1 Rough endoplasmic reticulum (rough ER) is a large system of interconnected, membranous, and convoluted sacks that are located in the cell's cytoplasm. The rough ER is connected to the outer nuclear membrane and to the smooth ER. Rough ER is covered with ribosomes that give it a rough appearance while the smooth ER does NOT have ribosomes on its surface. Rough ER transports materials through the cell and produces proteins in sacks called cisterns which are sent to the Golgi body, or inserted into the cell membrane. The Golgi apparatus or Golgi complex is a flattened, layered, sac-like organelle that looks like a stack of pancakes. The Golgi body modifies & packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell. Smooth ER makes proteins and lipids that will be exported by the cell. It also controls the Calcium level in muscles and detoxifies poisons, alcohol, and drugs. 14. Rough ER is connected to the _____________ membrane and to __________ER. 15. How does the appearance of rough ER differ from smooth ER? 16. The function (job) of rough ER is to ________________ and _________________. 17. The Golgi body ____________ and ___________ proteins for export out of the cell. 18. Give 3 jobs for smooth ER. Job 1 ; Job 2 ; Job 3 __________________________________________________________________________________________ Chloroplasts are elongated or disc-shaped organelles containing chlorophyll that trap sunlight for energy. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts. Only plant cells, not animal cells, have chloroplasts & can make their own food. Cells also contain fluid-filled sacs called vacuoles. The vacuole is filled with food being digested or waste material that is on its way out of the cell. In plant cells, a large central vacuole takes up most of the space in the cell. Mitochondria are spherical to peanut-shaped organelles with a double membrane. The mitochondrion converts the glucose into energy for the cell. Both plant chloroplasts and animal mitochondria have double membranes and their own DNA. Cells also contain rounded organelles called lysosomes that contain digestive enzymes. Nutrients are digested by the cell here, as well as, old cell organelles that are going to be recycled. 19. What do chloroplasts contain that traps sunlight for energy? 20. What process takes place inside chloroplasts? 21. Chloroplasts are found in what type of cell(s) only? 22. Food, water, and wastes are stored inside ______________. 23. The largest organelle in plants is the ____________ _____________. 24. Digestion takes place inside _____________ that contain _____________. 25. What organelle breaks down and recycles worn out cells? 2 Complete the following table: Organelle Plant/Animal/Both Function Cell membrane Cell wall Cytoplasm Vacuole Ribosome Golgi body Rough ER Smooth ER Central Vacuole Chloroplast Mitochondria Nucleus Nucleolus Nuclear membrane Centrioles Lysosomes Microtubules Nuclear pores 3 ANIMAL CELL NUCLEOLUS PLANT CELL 4 .
Load more

Recommended publications
  • For the Safe Delivery of Essential Proteins
    Dedicated ‘Bodyguards’ for the Safe Delivery of Essential Proteins Dr Brigitte Pertschy DEDICATED ‘BODYGUARDS’ FOR THE SAFE DELIVERY OF ESSENTIAL PROTEINS Ribosomes are undoubtedly one of the most essential cellular components in life. These macromolecules are responsible for the synthesis of proteins in all living cells. Dr Brigitte Pertschy, Dr Ingrid Rössler and Jutta Hafner at the Institute of Molecular Biosciences at the University of Graz, Austria, have discovered that the safe delivery of essential ribosomal proteins that make up the ribosomes is dependant on ‘private bodyguards’ or ‘chaperones’. Nascent Ribosomal Proteins Journey Ribosome synthesis is an important of their synthesis and proper folding Across the Cell to the Nucleus and continuous process. Dr Pertschy of the proteins. Importins have also describes that a growing cell requires been reported as aides in the import of The ribosome is the intricate nano- up to 1,000 ribosomes to be synthesised proteins to the cell nucleus as well as in machinery that translates messenger per minute. The r-proteins are protecting proteins from aggregation. RNA strands (mRNA) into protein. Our produced in the cell cytoplasm by the DNA holds the instructions for building ribosome itself (that way, the ribosome The team speculated that since every protein needed for our bodies to participates in its own reproduction). r-proteins are produced at extremely function. Initially, DNA is transcribed From there the r-proteins must travel high amounts and their correct into mRNA, which contains the amino to the cell nucleus where in a complex functioning is so critical for a cell, these acid sequence of a particular protein.
    [Show full text]
  • Building the Interphase Nucleus: a Study on the Kinetics of 3D Chromosome Formation, Temporal Relation to Active Transcription, and the Role of Nuclear Rnas
    University of Massachusetts Medical School eScholarship@UMMS GSBS Dissertations and Theses Graduate School of Biomedical Sciences 2020-07-28 Building the Interphase Nucleus: A study on the kinetics of 3D chromosome formation, temporal relation to active transcription, and the role of nuclear RNAs Kristin N. Abramo University of Massachusetts Medical School Let us know how access to this document benefits ou.y Follow this and additional works at: https://escholarship.umassmed.edu/gsbs_diss Part of the Bioinformatics Commons, Cell Biology Commons, Computational Biology Commons, Genomics Commons, Laboratory and Basic Science Research Commons, Molecular Biology Commons, Molecular Genetics Commons, and the Systems Biology Commons Repository Citation Abramo KN. (2020). Building the Interphase Nucleus: A study on the kinetics of 3D chromosome formation, temporal relation to active transcription, and the role of nuclear RNAs. GSBS Dissertations and Theses. https://doi.org/10.13028/a9gd-gw44. Retrieved from https://escholarship.umassmed.edu/ gsbs_diss/1099 Creative Commons License This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License This material is brought to you by eScholarship@UMMS. It has been accepted for inclusion in GSBS Dissertations and Theses by an authorized administrator of eScholarship@UMMS. For more information, please contact [email protected]. BUILDING THE INTERPHASE NUCLEUS: A STUDY ON THE KINETICS OF 3D CHROMOSOME FORMATION, TEMPORAL RELATION TO ACTIVE TRANSCRIPTION, AND THE ROLE OF NUCLEAR RNAS A Dissertation Presented By KRISTIN N. ABRAMO Submitted to the Faculty of the University of Massachusetts Graduate School of Biomedical Sciences, Worcester in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSPOPHY July 28, 2020 Program in Systems Biology, Interdisciplinary Graduate Program BUILDING THE INTERPHASE NUCLEUS: A STUDY ON THE KINETICS OF 3D CHROMOSOME FORMATION, TEMPORAL RELATION TO ACTIVE TRANSCRIPTION, AND THE ROLE OF NUCLEAR RNAS A Dissertation Presented By KRISTIN N.
    [Show full text]
  • Introduction to the Cell Cell History Cell Structures and Functions
    Introduction to the cell cell history cell structures and functions CK-12 Foundation December 16, 2009 CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the “FlexBook,” CK-12 intends to pioneer the generation and distribution of high quality educational content that will serve both as core text as well as provide an adaptive environment for learning. Copyright ©2009 CK-12 Foundation This work is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. Contents 1 Cell structure and function dec 16 5 1.1 Lesson 3.1: Introduction to Cells .................................. 5 3 www.ck12.org www.ck12.org 4 Chapter 1 Cell structure and function dec 16 1.1 Lesson 3.1: Introduction to Cells Lesson Objectives • Identify the scientists that first observed cells. • Outline the importance of microscopes in the discovery of cells. • Summarize what the cell theory proposes. • Identify the limitations on cell size. • Identify the four parts common to all cells. • Compare prokaryotic and eukaryotic cells. Introduction Knowing the make up of cells and how cells work is necessary to all of the biological sciences. Learning about the similarities and differences between cell types is particularly important to the fields of cell biology and molecular biology.
    [Show full text]
  • SMC Complexes Orchestrate the Mitotic Chromatin Interaction Landscape
    Curr Genet DOI 10.1007/s00294-017-0755-y REVIEW SMC complexes orchestrate the mitotic chromatin interaction landscape Yasutaka Kakui1 · Frank Uhlmann1 Received: 13 September 2017 / Revised: 14 September 2017 / Accepted: 16 September 2017 © The Author(s) 2017. This article is an open access publication Abstract Chromatin is a very long DNA–protein complex Keywords Chromosome condensation · SMC complex · that controls the expression and inheritance of the genetic Chromatin · Cell cycle · Hi-C information. Chromatin is stored within the nucleus in interphase and further compacted into chromosomes dur- ing mitosis. This process, known as chromosome condensa- Introduction tion, is essential for faithful segregation of genomic DNA into daughter cells. Condensin and cohesin, members of How chromatin is spatially organized within the cell nucleus the structural maintenance of chromosomes (SMC) fam- and within chromosomes is a fundamental question in cell ily, are fundamental for chromosome architecture, both biology. Centimeter-long DNA molecules change their spa- for establishment of chromatin structure in the interphase tial chromatin organization within micrometer-sized cells nucleus and for the formation of condensed chromosomes during cell cycle progression. In interphase, chromatin is in mitosis. These ring-shaped SMC complexes are thought distributed throughout the nucleus to express the genetic to regulate the interactions between DNA strands by topo- information. When cells enter mitosis, chromatin becomes logically entrapping DNA. How this activity shapes chro- compacted to form mitotic chromosomes. Chromosome mosomes is not yet understood. Recent high throughput condensation, the gross morphological change of spatial chromosome conformation capture studies revealed how chromatin organization in mitosis, is indispensable for chromatin is reorganized during the cell cycle and have the faithful inheritance of genetic information.
    [Show full text]
  • DNA Damage Alters Nuclear Mechanics Through Chromatin Reorganisation
    bioRxiv preprint doi: https://doi.org/10.1101/2020.07.10.197517; this version posted July 11, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. DNA damage alters nuclear mechanics through chromatin reorganisation Ália dos Santos1, Alexander W. Cook1, Rosemarie E Gough1, Martin Schilling2, Nora Aleida Olszok2, Ian Brown3, Lin Wang4, Jesse Aaron5, Marisa L. Martin-Fernandez4, Florian Rehfeldt2,6* and Christopher P. Toseland1* 1Department of Oncology and Metabolism, University of Sheffield, Sheffield, S10 2RX, UK.2University of Göttingen, 3rd Institute of Physics – Biophysics, Göttingen, 37077, Germany. 3School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK. 4Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford OX11 0QX, UK. 5Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, USA. 6University of Bayreuth, Experimental Physics 1, Bayreuth, 95440, Germany. *Corresponding Authors: Florian Rehfeldt [email protected] & Christopher P. Toseland [email protected] Key words: Mechanics, DNA damage, DNA organisation, Nucleus ABSTRACT Cisplatin, specifically, creates adducts within the DNA double-strand breaks (DSBs) drive genomic double helix, which then lead to double-strand instability. For efficient and accurate repair of breaks (DSBs) in the DNA during replication, these DNA lesions, the cell activates DNA through replication-fork collapse3. damage repair pathways. However, it remains DSBs can result in large genomic aberrations and unknown how these processes may affect the are, therefore, the most deleterious to the cell.
    [Show full text]
  • Cytochemical Features Common to Nucleoli and Cytoplasmic Nucleoloids of Olea Europaea Meiocytes: Detection of Rrna by in Situ Hybridization
    Journal of Cell Science 107, 621-629 (1994) 621 Printed in Great Britain © The Company of Biologists Limited 1994 JCS8341 Cytochemical features common to nucleoli and cytoplasmic nucleoloids of Olea europaea meiocytes: detection of rRNA by in situ hybridization J. D. Alché, M. C. Fernández and M. I. Rodríguez-García* Plant Biochemistry, Molecular and Cellular Biology Department, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, E- 18008 Granada, Spain *Author for correspondence SUMMARY We used light and electron microscopic techniques to study highly phosphorylated proteins. Immunohistochemical the composition of cytoplasmic nucleoloids during meiotic techniques failed to detect DNA in either structure. In situ division in Olea europaea. Nucleoloids were found in two hybridization to a 18 S rRNA probe demonstrated the clearly distinguishable morphological varieties: one similar presence of ribosomal transcripts in both the nucleolus and in morphology to the nucleolus, and composed mainly of nucleoloids. These similarities in morphology and compo- dense fibrillar component, and another surrounded by sition may reflect similar functionalities. many ribosome-like particles. Cytochemical and immuno- cytochemical techniques showed similar reactivities in nucleoloids and the nucleolus: both are ribonucleoproteic Key words: nucleoloids, nucleolar proteins, rRNA, in situ in nature, and possess argyrophillic, argentaffinic and hybridization INTRODUCTION lentum (Carretero and Rodríguez-García, unpublished observa- tions). The reason for this diversity is unknown. Cytoplasmic bodies similar in morphology and ultrastructural Nucleoloids have rarely been studied in genera other than characteristics to the nucleolus have been reported many times Lilium. Cytoplasmic nucleoloids are very common in Olea in relation to plant meiosis (Latter, 1926; Frankel, 1937; europaea during microsporogenesis and their large size and Hakansson and Levan, 1942; Gavaudan, 1948; Lindemann, peculiar morphological characteristics make them a good 1956).
    [Show full text]
  • Nucleolus: a Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky
    Nucleolus: A Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky To cite this version: Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, et al.. Nucleolus: A Central Hub for Nuclear Functions. Trends in Cell Biology, Elsevier, 2019, 29 (8), pp.647-659. 10.1016/j.tcb.2019.04.003. hal-02322927 HAL Id: hal-02322927 https://hal.archives-ouvertes.fr/hal-02322927 Submitted on 18 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Nucleolus: A Central Hub for Nuclear Functions Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, Sergey Razin, Yegor Vassetzky To cite this version: Olga Iarovaia, Elizaveta Minina, Eugene Sheval, Daria Onichtchouk, Svetlana Dokudovskaya, et al.. Nucleolus: A Central Hub for Nuclear Functions. Trends in Cell Biology, Elsevier, 2019, 29 (8), pp.647-659. 10.1016/j.tcb.2019.04.003. hal-02322927 HAL Id: hal-02322927 https://hal.archives-ouvertes.fr/hal-02322927 Submitted on 18 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not.
    [Show full text]
  • Mitochondria in the Nuclei of Rat Myocardial Cells
    cells Article Mitochondria in the Nuclei of Rat Myocardial Cells Chupalav M. Eldarov 1, Irina M. Vangely 1, Valeriya B. Vays 1, Eugene V. Sheval 1, Susanne Holtze 2 , Thomas B. Hildebrandt 2, Natalia G. Kolosova 3 , Vasily A. Popkov 1, Egor Y. Plotnikov 1 , Dmitry B. Zorov 1, Lora E. Bakeeva 1 and Vladimir P. Skulachev 1,4,* 1 A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; [email protected] (C.M.E.); [email protected] (I.M.V.); [email protected] (V.B.V.); [email protected] (E.V.S.); [email protected] (V.A.P.); [email protected] (E.Y.P.); [email protected] (D.B.Z.); [email protected] (L.E.B.) 2 Department of Reproduction Management, Leibniz-Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; [email protected] (S.H.); [email protected] (T.B.H.) 3 Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia; [email protected] 4 Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119992 Moscow, Russia * Correspondence: [email protected]; Tel.: +7-495-939-55-30 Received: 12 December 2019; Accepted: 5 March 2020; Published: 14 March 2020 Abstract: Electron microscopic study of cardiomyocytes taken from healthy Wistar and OXYS rats and naked mole rats (Heterocephalus glaber) revealed mitochondria in nuclei that lacked part of the nuclear envelope. The direct interaction of mitochondria with nucleoplasm is shown. The statistical analysis of the occurrence of mitochondria in cardiomyocyte nuclei showed that the percentage of nuclei with mitochondria was roughly around 1%, and did not show age and species dependency.
    [Show full text]
  • Unit 6-Nucleus
    Unit 6-Nucleus Dr. Pallee shree Nucleus • Nucleus is the most important organelle in the cell • It distinguishes eukaryotic from prokaryotic cells • By housing the cell's genome, the nucleus serves both as the repository of genetic information and as the cell's control center • DNA replication, transcription, and RNA processing all take place within the nucleus Cont… • A nucleus is a double-membraned eukaryotic cell organelle that contains the genetic material. • It appears in an oval shape averages 5µm in width. • It often lies in the centre of a cell • The nucleus was the first organelle to be discovered • Nuclei 1st discovered and named by Robert Brown • Role of nucleus 1st demonestrated by Max Hammerling Ultra structure of Nucleus 1. Nuclear envelope 2. nuclear pores 3. Nucleoplasm 4. Nucleolus 5. Chromosomes 1. Structure of Nuclear envelope • The nuclear envelope has a complex structure consisting of a) Two nuclear membranes separated by a perinuclear space measuring about 20–40 nm across b) Underlying nuclear lamina • The nucleus is surrounded by a system of two concentric membranes, called the inner and outer nuclear membranes • The inner and outer nuclear membranes are joined at nuclear pore complexes a. Nuclear membranes • The outer nuclear membrane is continuous with the endoplasmic reticulum, so the space between the • The critical function of the inner and outer nuclear membranes nuclear membranes is to act as is directly connected with the lumen a barrier that separates the of the ER contents of the nucleus from the cytoplasm. • It is functionally similar to the membranes of the ER and has • Like other cell membranes, ribosomes bound to its cytoplasmic each nuclear membrane is a surface but protein composition phospholipid bilayer differ slightly as they are enriched in permeable only to small proteins which binds to cytoskeleton nonpolar molecules • The inner nuclear membrane carries • Other molecules are unable to proteins that are specific to the diffuse through the bilayer.
    [Show full text]
  • Condensed DNA: Condensing the Concepts
    Progress in Biophysics and Molecular Biology 105 (2011) 208e222 Contents lists available at ScienceDirect Progress in Biophysics and Molecular Biology journal homepage: www.elsevier.com/locate/pbiomolbio Review Condensed DNA: Condensing the concepts Vladimir B. Teif a,b,*, Klemen Bohinc c,d a BioQuant and German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany b Institute of Bioorganic Chemistry, Belarus National Academy of Sciences, Kuprevich 5/2, 220141, Minsk, Belarus c Faculty of Health Sciences, Zdravstvena pot 5, 1000 Ljubljana, Slovenia d Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, 1000 Ljubljana, Slovenia article info abstract Article history: DNA is stored in vivo in a highly compact, so-called condensed phase, where gene regulatory processes Available online 16 July 2010 are governed by the intricate interplay between different states of DNA compaction. These systems often have surprising properties, which one would not predict from classical concepts of dilute solutions. The Keywords: mechanistic details of DNA packing are essential for its functioning, as revealed by the recent devel- DNA condensation opments coming from biochemistry, electrostatics, statistical mechanics, and molecular and cell biology. Ligand binding Different aspects of condensed DNA behavior are linked to each other, but the links are often hidden in Counterion correlations the bulk of experimental and theoretical details. Here we try to condense some of these concepts and Macromolecular crowding fi Chromatin provide interconnections between the different elds. After a brief description of main experimental Gene regulation features of DNA condensation inside viruses, bacteria, eukaryotes and the test tube, main theoretical approaches for the description of these systems are presented.
    [Show full text]
  • Chloroplast Genes Are Expressed During Intracellular Symbiotic
    Proc. Natl. Acad. Sci. USA Vol. 93, pp. 12333-12338, October 1996 Cell Biology Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica (photosystem II reaction center/photosynthesis/chromophytic alga/ascoglossan mollusc/gene expression) CESAR V. MUJER*t, DAVID L. ANDREWS*t, JAMES R. MANHART§, SIDNEY K. PIERCES, AND MARY E. RUMPHO*II Departments of *Horticultural Sciences and §Biology, Texas A & M University, College Station, TX 77843; and IDepartment of Zoology, University of Maryland, College Park, MD 20742 Communicated by Martin Gibbs, Brandeis University, Waltham, MA, August 16, 1996 (received for review January 26, 1996) ABSTRACT The marine slug Elysia chlorotica (Gould) lowing metamorphosis from the veliger stage when juvenile forms an intracellular symbiosis with photosynthetically ac- sea slugs begin to feed on V litorea cells (1, 2). Once ingested, tive chloroplasts from the chromophytic alga Vaucheria litorea the chloroplasts are phagocytically incorporated into the cy- (C. Agardh). This symbiotic association was characterized toplasm of one of two morphologically distinct, epithelial cells over a period of 8 months during which E. chlorotica was (3) and maintain their photosynthetic function (1, 3). The deprived of V. litorea but provided with light and CO2. The fine plastids are frequently found in direct contact with the host structure of the symbiotic chloroplasts remained intact in E. cytoplasm as revealed by ultrastructural studies (3). In nature, chlorotica even after 8 months of starvation as revealed by the adult animal feeds on algae only sporadically, obtaining electron microscopy. Southern blot analysis of total DNA metabolic energy from the photosynthetic activity of the from E.
    [Show full text]
  • Structure of the Nucleoli in Domestic Cattle Spermatocytes
    FOLIA HISTOCHEMICA ORIGINAL STUDY ET CYTOBIOLOGICA Vol. 50, No. 3, 2012 pp. 346–351 Structure of the nucleoli in domestic cattle spermatocytes Katarzyna Andraszek, Elżbieta Smalec Department of Animal Genetics and Horse Breeding, Institute of Bioengineering and Animal Breeding, Siedlce University of Life Sciences and Humanities, Siedlce, Poland Abstract: The use of AgNO3 staining, commonly applied in cytogenetics to identify nucleolar organizer regions, has made it possible to identify nucleoli in primary spermatocytes. One nucleolus was identified in each ana- lyzed cell. Considerable morphological differentiation of the nucleoli during the prophase of the first meiotic division, particularly in leptotene, unobserved in other farm animal species, was noticed. Dark-hued grain-like structures were found within the disintegrating nucleoli, corresponding approximately or exactly to the number of the nucleolar organizer regions in the domestic cattle karyotype. Dark areas were identified in the selected prometaphase chromosomes. Their number corresponded with the number of active NORs defined in the do- mestic cattle karyotype. (Folia Histochemica et Cytobiologica 2012, Vol. 50, No. 3, 346–351) Key words: nucleolus, domestic cattle, bull, spermatogenesis, meiotic chromosomes Introduction bosome subunits are transported to the cytoplasm where they mature [1–3]. The nucleolus is the largest and best explored func- The nucleolus is a metaphase nuclear structure, tional component of the cell nucleus. Ribosomal perfectly visible with a light microscope. This is due RNA precursors (pre-rRNA) are synthesized in the to its considerable density, much greater than the den- nucleolus. It is also instrumental in the generation sity of the surrounding nucleoplasm and chromatin. and maturation of ribosomal RNP molecules (pre- The high density stems from a low water content and rRNP).
    [Show full text]