Attachment strips: a new type of hemidesmosome-like structure in the protozoon Katablepharis ovalis Skuja
|
|
- Nathaniel Ward
- 5 years ago
- Views:
Transcription
1 Attachment strips: a new type of hemidesmosome-like structure in the protozoon Katablepharis ovalis Skuja ROBERT EDWARD LEE Department of Anatomy and Neurobiology, Colorado State University, Fort Collins, CO 80533, USA and PAUL KUGRENS Department of Biology, Colorado State University, Fort Collins, CO 80523, USA Summary Katablepharis ovalis Skuja is a free-living unicellular flagellate with a phagocytic mode of nutrition. Each cell has one or two hemidesmosome-like attachment strips consisting of electron-dense ridges that pass through the plasma membrane to end at the inner wall. Each attachment strip occurs over a group of microtubules of the cytoskeleton and, like the cytoskeleton, is oriented along the long axis of the cell. The attachment strips occur only over the medial area of the cell and are not found over the anterior one-third or posterior one-sixth of the cell. The attachment strips appear to function like hemidesmosomes, attaching the cell to the extracellular matrix. However, the attachment strips in Katablepharis do not have the cytoplasmic component of hemidesmosomes, e.g. fibrils and electron-dense plaques. Among unicellular organisms, hemidesmosomes have been previously reported only in trypanosomes, where hemidesmosomes on an expanded flagellum attach the parasite to the cuticle of the alimentary canal of the insect host. The possible relationship between the attachment strips in Katablepharis and the hemidesmosomes in trypanosomes is discussed. Key words: Katablepharis, attachment strip, trypanosome, hemidesmosome Introduction A hemidesmosome i8 a specialized area of the plasma membrane that serves to attach a cell to the extracellular matrix. Hemidesmosomes are common in higher animals, where they secure the cell to the basal lamina (Staehelin, 1974; Staehelin and Hull, 1978). Among unicellular organisms, hemidesmosomes and desmo9omes have only been found in trypanosomes (Killick-Kendrick et al. 1974; Molyneux, 1977; Gardner and Molyneux, 1988; Walters et al. 1989). During an ultrastructural investigation of Katablepharis ovalis, a free-living, phagocytic flagellate, we observed a specialized area of the plasma membrane that appeared to secure the cell wall to the plasma membrane. While the specialized area of the plasma membrane in Katablepharis appeared to be functionally similar to a hemidesmosome, it differed somewhat structurally. The following report describes this structure, which we have called an attachment atrip. Materials and methods Katablepharis ovalis was isolated from pond A-l of the Depart- Journal of Cell Science 98, (1991) Printed in Great Britain The Company of Biologista Limited 1991 ment of Energy's Rocky Flats Nuclear-Weapons Plant near Golden, Colorado. Katablepharis was isolated into a bialgal culture with Chrysochromuhna, on which Katablepharis feeds. The organisms were grown in sterilized water from Dowdy Lake, Red Feather, Colorado, which had 40 ml of Algal-Gro (Carolina Biological Supply) added per liter. Micrographs of thin-sectioned material fixed by conventional glutaraldehyde-osmium tetroxide fixation were obtained using previously described methods (Kugrens and Lee, 1988). Freezefracture replicas were obtained by 'slamming' living cells against a liquid nitrogen-cooled copper block, followed by freeze fracture according to the method of Kugrens and Lee (1987). Results Katablepharis ovalis is a biflagellate unicell that has a two-layered wall surrounding the cell body and flagella (Fig. 1A). The cell has an anterior mouth and feeding apparatus, a central nucleus, and one or more posterior food vacuoles (Fig. 1A). An outer cytoskeleton, composed of groups of four to eight microtubules occurs beneath the plasma membrane, arranged along the long axis of the cell. Each cell has one or two attachment strips composed of thin ridges of electron-dense material that pass through the plasma membrane to terminate at the inner layer of the wall (Figs 1B,C, 2). The ridges of electron-dense 245
2 v mt * i \ w as ' B Fig. 1. Micrographs of thin sections of Katablepharis. (A) Longitudinal section of a cell showing the flagella (f), the anterior mouth (m), the two-layered wall (w) surrounding the cell, the microtubules (mt) of the cytoskeleton, the nucleus and the posterior food vacuole (fv). Bar, 1 /an. (B) A portion of a cross-section of a cell showing an attachment strip (as) occurring outside of a group of four microtubules of the cytoskeleton. n, nucleus; p, plasma membrane; rer, cisternum of rough endoplasmic reticulum; w, wall. Bar, 0.5 /an. (C) A fairly thick cross-section of a cell at the level of the nucleus. The two attachment strips (as) appear as electrondense material between the plasma membrane and the inner wall (w) in areas outside the microtubules (mt) of the cytoskeleton. Bar, 0.5 /an. material are 12 nm apart. A 'thick' thin section (Fig. 1C) shows that the inner wall is closely pressed to the electrondense material of the attachment strip. The attachment strip is always oriented directly over one of the micro tubular groups of the cytoskeleton (Figs 1B,C, 2, 3A). Attachment strips occur only over the medial area of the cell and do not extend into the anterior one-third of the cell (Fig. 3A) or into the posterior one-sixth of the cell. The exact microtubular group of the cytoskeleton with an attachment strip varies; attachment strips have been seen on ventral, lateral and dorsal surfaces. In freeze-fracture replicas, an attachment strip is visible as rows of projections of irregular size on the protoplasmic face (P-face) of the plasma membrane (Fig. 3A-C). The irregular nature of the projections and ridges is probably due to distortion during the fracture, a common phenomenon. The microtubular groups of the cytoskeleton commonly occur as indentations in the P face of the plasma membrane, with the ridges and projections of the attachment strip occurring over the microtubular group (Fig. 3A). The extracellular face (E face) of the plasma membrane at the attachment strip has four to eight linear 246 R. E. Lee and P. Kugrens slits, 12 nm apart (Fig 3D,E). Sometimes, the E-face slits have a cross-hatched appearance, with the slits having a regular structure parallel and perpendicular to the long axis of the attachment strip (Fig. 3E). Occasionally, the projections of the attachment strip pull off a P face during fracture, revealing slits in the P face similar to the slits in the E face (Fig. 3C). Discussion Drosophila wing epidermal cells have microtubules associated with hemidesmosomes (Mogensen and Tucker, 1987, 1988; Tucker et al. 1986). The hemidesmosomes in Drosophila wing epidermal cells have electron-dense material on each side of the plasma membrane, as do the attachment strips of Katablepharis. In Drosophila wing epidermal cells, the exterior electron-dense material of the hemidesmosome appears to attach the plasma membrane to the cuticle (see Fig. 11, Mogensen and Tucker, 1987), similar to the situation in Katablepharis. However, in
3 OUTER WALL INNER WALL ATTACHMENT STRIP o o ooo o PLASMA MEMBRANE CYTOPLASM MICRQTUBULES Fig. 2. A schematic drawing of the structure of an attachment strip and associated structures. Drosophila wing epidermal cells, the electron-dense material is not organized into distinct ridges spanning the plasma membrane, as it is in Katablepharis. Also in Drosophila wing epidermal cells, the microtubules terminate near, and at right angles to, the hemidesmosome. Mogensen and Tucker (1987) postulate that some of the electron-dense material of the Drosophila hemidesmosome is responsible for the formation of the microtubules adjacent to the hemidesmosome. This is probably not the case in Katablepharis where the microtubules associated with the attachment strips are oriented parallel to, and do not terminate near, the attachment strips. Among unicellular organisms, hemidesmosomes have only been reported in the trypanosomes. In the trypanosomes, hemidesmosomes on an expanded flagellum attach the cell to the cuticle of the alimentary canal of the insect host (Killick-Kendrick et al. 1974; Molyneux, 1977; Gardner and Molyneux, 1988; Walters et al. 1989). The attachment strips in Katablepharis do not have the welldeveloped cytoplasmic system of electron-dense fibrils and plaques that occur in hemidesmosomes in the trypanosomes and multicellular organisms (Staehelin, 1974; Staehelin and Hull, 1978; Gipson et al. 1983). However, an attachment strip in Katablepharis is closely associated with a microtubular group of the cytoskeleton. The linearly arranged microtubules of the cytoskeleton may provide the mechanical support given by electron-dense fibrils and plaques of hemidesmosomes in other organisms. Also, the wall of Katablepharis may not be bound very tightly to the plasma membrane, so the fibrils and electron-dense plaques associated with the stronger hemidesmosome may not be necessary. More robust hemidesmosomes may be required to attach a trypano- some to the cuticle of the alimentary canal of an insect, or to attach epithelial cells to a basal lamina in multicellular organisms. Indeed, one wonders why Katablepharis has an attachment strip at all. There are a large number of organisms, both unicellular and multicellular, motile and non-motile, that have an extracellular matrix in the form of a cell wall or theca. An attachment strip or hemidesmosome has never been reported in these organisms. It, therefore, seems unlikely that the simple presence of a wall requires an attachment strip. There must be a unique situation in Katablepharis that requires the presence of an attachment strip. It is our belief that this unique situation in Katablepharis is the phagocytic mode of nutrition coupled with the presence of a wall. We believe that the mouth of Katablepharis attaches the cell to its prey and that the contents of the prey are taken into food vacuoles in Katablepharis, much like the ingestion of prey in suctorians. Attachment of Katablepharis to a prey organism would require an opening in the anterior end of the extracellular matrix to expose the mouth to the prey. The active ingestion would result in a rearrangement of the inner wall. The positioning of the opening in the anterior portion of the extracellular matrix may not be possible unless the inner wall is anchored to the plasma membrane by attachment strips in the medial portions of the cell. It is interesting to speculate on the possible relationship between the attachment strip in Katablepharis and the hemidesmosome. Katablepharis is probably a very old organism in terms of evolution. It is possible that the relatively simple structure of the attachment strip evolved into the more complex hemidesmosome as evolution progressed. Such an evolutionary progression would have resulted in the loss of the association of microtubules with Attachment strips 247
4 3A Fig. 3. Transmission electron micrographs of freeze-fracture replicas of cells rapidly frozen by 'slamming*, showing the structure of the attachment strips in the plasma membrane. Bars, 0.1 jnn. (A) This fracture of the protoplasmic face of the plasma membrane shows the mouth (m) at the anterior end of the cell. Three groups of microtubules of the cytoskeleton are represented by indentations of the plasma membrane (arrowheads). The attachment strip (as) is seen at the bottom of the micrograph as a strip of projections over one of the microtubular groups of the cytoskeleton. (B,C) Replicas of the P face of the plasma membrane in the area of the attachment strip. The projections arising out of the P face are the electron-dense ridges that traverse the plasma membrane in thin sections. Some of the ridges are missing over the P face of the plasma membrane in C, revealing the linear slits in the P face through which the ridges project (arrowhead). (D,E) Replicas of the extracellular face (E face) of the plasma membrane, showing the structure of the attachment strip. (D) The usual appearance of the E face with linear ridges and a few intra-membrane particles interdispersed along the strip. (E) Occasionally the E face of the plasma membrane in the attachment strip has a cross-hatched appearance. 248 R. E. Lee and P. Kugrens
5 the attachment strip, and the development of cytoplasmic filaments with a cytoplasmic plaque to form the hemidesmosome. We thank Dr Andrew Staehelin for reading the manuscript and making helpful suggestions. References GARDNER, R. A. AND MOLYNEUX, D. H. (1988). Trypanosoma {Megatrypanum) mcertum from Pipistrellus: development and transmission by cimicid bugs. Parasitology 98, GIPSON, I. K., GRILL, S. M., SPURH, S. J. AND BRENNAN, S. J. (1983). Hemidesmosome formation in vitro. J. Cell Biol. 97, KILUCK-KKNDRJCK, R., MOLYNEUX, D. H. AND ASHFORD, R, W. (1974). Leishmania in phlebotomid sandflies. I. Modifications of the flagellum associated with the attachment to the mid-gut and oesophageal valve of the sandfly. Proc. ft. Soc. hand. B, 187, KUGRBNS, P. AND LEE, R. E. (1987). An ultrastructural survey of cryptomonad periplasts using quick-freezing freeze-fracture techniques. J. Phycol 23, KUORENS, P. AND LEE, R. E. (1988). Ultrastructure of fertilization in a cryptomonad. J. Phycol. 24, MOCENSEN, M. M. AND TUCKER, J. B. (1987). Evidence for microtubule nucleation at plasma membrane-associated sites in Drosophila J. Cell Sci. 88, MOGENSEN, M. M. AND TUCKER, J B. (1988). Intermicrotubular actin filaments in the transalar cytoskeletal arrays of Drosophila. J. Cell Sci. 91, MOLYNEUX, D. H. (1977). Vector relationships in the Trypanosomatidae. Adv. ParasU. 15, STAEHELIN, L. A. (1974). Structure and function of intercellular junctions. Int. Rev. Cytol. 39, STABHEUN, L A. AND HULL, B. E. (1978). Junctions between living cells. Sci Amer. 238 (May), TUCKER, J. B., MILNKR, M. J., CURRIE, D. A., MUIR, J. W., FORREST, D. A. AND SPENCER, M. J. (1986) Centrosomal microtubule-organizing centres and a switch in the control of protofilament number for cell surface-associated microtubules during Drosophila wing morphogenesis. Eur. J. Cell Bwl. 41, WAI/TEBS, L. L., CHAPLIN, G. L., MODI, G. B. AND TESH, R. B. (1989). Ultrastructural biology of Leishmania (Viannia) panamensis (=Leishmania braziliensis panamensis) in Lutzomyia gomezi (Diptera:Psychodidae): A natural host-parasite association. Am. J. trop. Med. Hyg. 40, (Received 29 August Accepted 10 October 1990) Attachment strips 249
6
BIO 311C Spring 2010
BIO 311C Spring 2010 Prokaryotic cells contain structures that are very similar to structures of the eukaryotic cytoskeleton. Prokaryotic cytoskeletal elements are required for cell division, maintaining
More informationChapter 4 Active Reading Guide A Tour of the Cell
Name: AP Biology Mr. Croft Chapter 4 Active Reading Guide A Tour of the Cell Section 1 1. The study of cells has been limited by their small size, and so they were not seen and described until 1665, when
More information7-2 Eukaryotic Cell Structure
1 of 49 Comparing the Cell to a Factory Eukaryotic Cell Structures Structures within a eukaryotic cell that perform important cellular functions are known as organelles. Cell biologists divide the eukaryotic
More informationChapter 6: A Tour of the Cell
Chapter 6: A Tour of the Cell 1. The study of cells has been limited by their small size, and so they were not seen and described until 1665, when Robert Hooke first looked at dead cells from an oak tree.
More informationGolgi Apparatus. BIOLOGY 1408 Chapter 4 : Tour of the cell part II 9/28/15
BIOLOGY 1408 Chapter 4 : Tour of the cell part II Golgi Apparatus n The Golgi apparatus functions in conjunction with the ER by modifying products of the ER Products travel in transport vesicles from the
More informationA. The Cell: The Basic Unit of Life. B. Prokaryotic Cells. D. Organelles that Process Information. E. Organelles that Process Energy
The Organization of Cells A. The Cell: The Basic Unit of Life Lecture Series 4 The Organization of Cells B. Prokaryotic Cells C. Eukaryotic Cells D. Organelles that Process Information E. Organelles that
More informationChapter 6: A Tour of the Cell
AP Biology Reading Guide Fred and Theresa Holtzclaw Chapter 6: A Tour of the Cell Name Period Chapter 6: A Tour of the Cell Concept 6.1 To study cells, biologists use microscopes and the tools of biochemistry
More informationZimmerman AP Biology CBHS South Name Chapter 7&8 Guided Reading Assignment 1) What is resolving power and why is it important in biology?
Zimmerman AP Biology CBHS South Name Chapter 7&8 Guided Reading Assignment 1) What is resolving power and why is it important in biology? 2) How does an electron microscope work and what is the difference
More informationUnicellular Marine Organisms. Chapter 4
Unicellular Marine Organisms Chapter 4 The Cellular Structure of Life: Review Cell wall: firm, fairly rigid structure located outside the plasma membrane of plants, fungi, most bacteria, and some protists;
More informationBiology. 7-2 Eukaryotic Cell Structure 10/29/2013. Eukaryotic Cell Structures
Biology Biology 1of 49 2of 49 Eukaryotic Cell Structures Eukaryotic Cell Structures Structures within a eukaryotic cell that perform important cellular functions are known as organelles. Cell biologists
More informationChapter 7 Learning Targets Cell Structure & Function
Name: Chapter 7 Learning Targets Cell Structure & Function a. Define the word cell: 1. I know the history of the cell: b. Who discovered the cell? What did he observe? 2. I can list the three parts of
More informationCell Structure. Chapter 4. Cell Theory. Cells were discovered in 1665 by Robert Hooke.
Cell Structure Chapter 4 Cell Theory Cells were discovered in 1665 by Robert Hooke. Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Schleiden and Schwann proposed
More informationConcept 6.1 To study cells, biologists use microscopes and the tools of biochemistry
Name Period Chapter 6: A Tour of the Cell Concept 6.1 To study cells, biologists use microscopes and the tools of biochemistry 1. The study of cells has been limited by their small size, and so they were
More informationCell Theory. Cell Structure. Chapter 4. Cell is basic unit of life. Cells discovered in 1665 by Robert Hooke
Cell Structure Chapter 4 Cell is basic unit of life Cell Theory Cells discovered in 1665 by Robert Hooke Early cell studies conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Schleiden &
More informationAsk yourself. Chapter 3 Cell Structure and Function. Examples of Cells. A is cell the smallest unit that is capable of performing life functions.
Chapter 3 Cell Structure and Function Ask yourself If you were a scientist living in the 1500s, what kind of questions would you ask yourself if you were the one to discover cells? Let me think. Cell Video
More informationWorld of The Cell. How big is a cell?
World of The Cell Chapter 4 How big is a cell? The smallest cell is a Mycoplasmas (very small bacteria are barely bigger) Bacteria are just bigger than a single organelle of a animal cell Plant and animal
More informationForm a Hypothesis. Variables in an Experiment Dependent Variable what is being measured (data) Form a Hypothesis 2. Form a Hypothesis 3 15:03 DRY MIX
Scientific Method 1. Ask a question (Make observation) 2. Do some research 3. Form a Hypothesis MUST BE TESTABLE!! A possible explanation for a phenomenon. 4. Test Hypothesis/collect data (experiment time!)
More informationCell Structure. Chapter 4
Cell Structure Chapter 4 Cell Theory Cells were discovered in 1665 by Robert Hooke. Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Schleiden and Schwann proposed
More informationTopic 3: Cells Ch. 6. Microscopes pp Microscopes. Microscopes. Microscopes. Microscopes
Topic 3: Cells Ch. 6 -All life is composed of cells and all cells have a plasma membrane, cytoplasm, and DNA. pp.105-107 - The development of the microscope was the key to understanding that all living
More informationBio 111 Study Guide Chapter 6 Tour of the Cell
Bio 111 Study Guide Chapter 6 Tour of the Cell BEFORE CLASS: Reading: Read the whole chapter from p. 93-121, mostly skimming Concept 6.1 on microscopy. Figure 6.8 on pp. 100-101 is really helpful in showing
More informationName: Class: Date: ID: A
Class: Date: Ch 7 Review Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Researchers use fluorescent labels and light microscopy to a. follow
More informationFig. 16. Majority rule consensus tree depicting phylogenetic relationships inferred among 74 species of heterokont algae. Note that A.
Plate 1 Figs. 1-8. Light microscopic images of Anthophysa vegetans colonies and individual motile cells. Figs 1-5. Stalked (arrow; Figs 1,2) or unstalked (Figs 3-5) colonies consisting of ca. 10-20 spherical
More informationBasic Structure of a Cell
Basic Structure of a Cell Prokaryotic Cells No nucleus Archaea & Eubacteria One circular chromosome Extremely small Eukaryotic Cells Has a nucleus!!! Membrane-bound organelles Plants, Animals, Fungi, &
More informationChapter 4: Cells: The Working Units of Life
Name Period Chapter 4: Cells: The Working Units of Life 1. What are the three critical components of the cell theory? 2. What are the two important conceptual implications of the cell theory? 3. Which
More informationA. The Cell: The Basic Unit of Life. B. Prokaryotic Cells. C. Eukaryotic Cells. D. Organelles that Process Information
The Organization of Cells A. The Cell: The Basic Unit of Life Lecture Series 4 The Organization of Cells B. Prokaryotic Cells C. Eukaryotic Cells D. Organelles that Process Information E. Organelles that
More informationChapter 6 A Tour of the Cell
Chapter 6 A Tour of the Cell The cell is the basic unit of life Although cells differ substantially from one another, they all share certain characteristics that reflect a common ancestry and remind us
More informationEukaryotic cells are more complex than prokaryotic cells. They are identified by the presence of certain membrane-bound organelles.
Eukaryotic Cells Eukaryotic cells are more complex than prokaryotic cells. They are identified by the presence of certain membrane-bound organelles. Prokaryotic cells have organelles too, but much fewer
More informationCHARACTERISTICS OF LIFE ORGANIZATION OF LIFE CELL THEORY TIMELINE
CHARACTERISTICS OF LIFE 1. composed of cells either uni/multi 2. reproduce sexual and/or asexual 3. contain DNA in cells 4. grow and develop 5. use material/energy in metabolic reactions 6. respond to
More informationZimmerman AP Biology CBHS South Name Chapter 7&8 Guided Reading Assignment 1) What is resolving power and why is it important in biology?
Zimmerman AP Biology CBHS South Name Chapter 7&8 Guided Reading Assignment 1) What is resolving power and why is it important in biology? 2) How does an electron microscope work and what is the difference
More informationCELLS STRUCTURE AND FUNCTION
CELLS STRUCTURE AND FUNCTION Jhia Anjela D. Rivera Department of Biological Sciences School of Science and Technology Centro Escolar University DISCOVERY OF CELLS Robert Hooke (1665): Observed a thin slice
More informationIntroduction to Cells
Life Science Introduction to Cells All life forms on our planet are made up of cells. In ALL organisms, cells have the same basic structure. The scientist Robert Hooke was the first to see cells under
More informationHonors Biology-CW/HW Cell Biology 2018
Class: Date: Honors Biology-CW/HW Cell Biology 2018 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Hooke s discovery of cells was made observing a. living
More informationPre-lab Homework Lab 4: The Cell
Lab Section: Name: Pre-lab Homework After reading over the lab and the cell chapter in your textbook, answer these questions to be turned in at the beginning of the lab! 1. Define organelle : Two examples
More informationChapter 4. Table of Contents. Section 1 The History of Cell Biology. Section 2 Introduction to Cells. Section 3 Cell Organelles and Features
Cell Structure and Function Table of Contents Section 1 The History of Cell Biology Section 2 Introduction to Cells Section 3 Cell Organelles and Features Section 4 Unique Features of Plant Cells Section
More informationIntroduction to Animals
Introduction to Animals Characteristics of Animals multicellular Except for sponges, animal cells are arranged into tissues. Tissues are necessary to produce organs and organ systems. Tissues, organs,
More informationLecture Series 3 The Organization of Cells
Lecture Series 3 The Organization of Cells Reading Assignments Read Chapter 15 Endomembrane System Read Chapter 17 Cytoskeleton A. The Cell: The Basic Unit of Life Cell Theory: All cells come from preexisting
More informationLecture Series 3 The Organization of Cells
Lecture Series 3 The Organization of Cells Reading Assignments Read Chapter 15 Endomembrane System Read Chapter 17 Cytoskeleton A. The Cell: The Basic Unit of Life Cell Theory: All cells come from preexisting
More informationReading Assignments. A. The Cell: The Basic Unit of Life. Lecture Series 3 The Organization of Cells
Lecture Series 3 The Organization of Cells Reading Assignments Read Chapter 15 Endomembrane System Read Chapter 17 Cytoskeleton A. The Cell: The Basic Unit of Life Cell Theory: All cells come from preexisting
More informationBIOLOGY 311C - Brand Spring 2007 EXAMINATION I
BIOLOGY 311C - Brand Spring 2007 NAME (printed very legibly) Key UT-EID EXAMINATION I Before beginning, check to be sure that this exam contains 7 pages (including front and back) numbered consecutively,
More informationMicrobiology: A Systems Approach
Microbiology: A Systems Approach First Edition Cowan &Talaro Chapter 5 Eucaryotic cells and microorganisms Chapter 5 2 3 Eucaryotic cells 3 Flagella 4 Cilia similar in overall structure to flagella, but
More informationDr. Dina A. A. Hassan Associate Professor, Pharmacology
Cytology Dr. Dina A. A. Hassan Associate Professor, Pharmacology Email: da.hassan@psau.edu.sa Cells All living things are made up of cells Basic building blocks of life It is the smallest functional and
More informationGuided Reading Activities
Name Period Chapter 4: A Tour of the Cell Guided Reading Activities Big Idea: Introduction to the Cell Answer the following questions as you read Modules 4.1 4.4: 1. A(n) uses a beam of light to illuminate
More informationNow starts the fun stuff Cell structure and function
Now starts the fun stuff Cell structure and function Cell Theory The three statements of the cell theory are: All organisms are composed of one or more cells and the processes of life occur in these cells.
More informationIntroduction to Cells
Life Science Introduction to Cells All life forms on our planet are made up of cells. In ALL organisms, cells have the same basic structure. The scientist Robert Hooke was the first to see cells under
More informationPrinciples of Cellular Biology
Principles of Cellular Biology آشنایی با مبانی اولیه سلول Biologists are interested in objects ranging in size from small molecules to the tallest trees: Cell Basic building blocks of life Understanding
More informationSTUDY GUIDE SECTION 4-1 The History of Cell Biology
STUDY GUIDE SECTION 4-1 The History of Cell Biology Name Period Date Multiple Choice-Write the correct letter in the blank. 1. One early piece of evidence supporting the cell theory was the observation
More informationUnit 2: Characteristics of Living Things Lesson 18: From Cell To Organism
Name Unit 2: Characteristics of Living Things Lesson 18: From Cell To Organism Date Objective: Students will be able to compare organisms unique cells and cellular organization. Essential Questions: 1.
More informationParenchyma Cell. Magnification 2375X
Parenchyma Cell The large size of parenchyma cells is due in part to their relatively large vacuole (V) and in part also to the large number of chloroplasts (Cp) they contain. From a crimson clover, Trifolium
More informationChapter 16. Cellular Movement: Motility and Contractility. Lectures by Kathleen Fitzpatrick Simon Fraser University Pearson Education, Inc.
Chapter 16 Cellular Movement: Motility and Contractility Lectures by Kathleen Fitzpatrick Simon Fraser University Two eukaryotic motility systems 1. Interactions between motor proteins and microtubules
More informationMultiple Choice Identify the letter of the choice that best completes the statement or answers the question.
chapter 7 Test Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Who was one of the first people to identify and see cork cells? a. Anton van
More informationT HE C ELL C H A P T E R 1 P G. 4-23
T HE C ELL C H A P T E R 1 P G. 4-23 A CELL IS THE SMALLEST LIVING UNIT KNOWN. IT IS OFTEN CALLED THE BUILDING BLOCK OF THE BODY, AND IS THE BASIC STRUCTURAL AND FUNCTIONAL UNIT OF AN ORGANISM. CELL THEORY
More informationBiology Cell Test. Name: Class: Date: ID: A. Multiple Choice Identify the choice that best completes the statement or answers the question.
Class: Date: Biology Cell Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1, Who. wasone of the first people to-identify and seecorkeells? -,- ; -...
More informationCell structure and functions
Cell structure and functions Cells: The cell is the basic structural and functional unit of life. All living organisms are made up of cells. Cells make tissues, tissues make organs, organs make organ systems
More informationCell (Learning Objectives)
Cell (Learning Objectives) 1. Understand & describe the basic components necessary for a functional cell. 2. Review the order of appearance of cells on earth and explain the endosymbiotic theory. 3. Compare
More informationGreat Ideas of Biology
Great Ideas of Biology Lecture 2 Alan Mortimer PhD The Cell as the Basic Unit of Life Lecture 2 HeLa Cells Fentonics The Basic Unit In all science we have look for the most basic unit We also seem to want
More informationSTEMscopedia: PLANT AND ANIMAL CELLS
B.L 14.2 and 14.3 Reflect Take a moment to think about all of the living things on Earth. There is great diversity among organisms, from microscopic bacteria to massive blue whales the largest animals
More informationOutline. Cell Structure and Function. Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles. Chapter 4
Cell Structure and Function Chapter 4 Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles! Nucleus Outline! Endomembrane System! Cytoskeleton! Centrioles, Cilia, and Flagella 1 2 Cell Theory
More informationClass IX: Biology Chapter 5: The fundamental unit of life. Chapter Notes. 1) In 1665, Robert Hooke first discovered and named the cells.
Class IX: Biology Chapter 5: The fundamental unit of life. Key learnings: Chapter Notes 1) In 1665, Robert Hooke first discovered and named the cells. 2) Cell is the structural and functional unit of all
More informationModule 2: Foundations in biology
alevelbiology.co.uk Module 2: Foundations in biology SPECIFICATION 2.1.1 Cell structure Learners should be able to demonstrate and apply their knowledge and understanding of: (a) The use of microscopy
More informationGoals: Viruses: not considered alive. Living cells. Plants. Bacteria. Animals. Archae Bacteria. Protists. Fungi. The prokaryotic cell structure
Goals: Identify the structures of eukaryotic and prokaryotic cells Identify the differences between viruses, prokaryotes and eukaryotes Use knowledge about differences between types of cells to solve a
More informationHonors Biology summer assignment. Review the notes and study them. There will be a test on this information the 1 st week of class
Honors Biology summer assignment Review the notes and study them. There will be a test on this information the 1 st week of class Biomolecules Molecules that make up living things. There are 4 molecules
More information10/1/2014. Chapter Explain why the cell is considered to be the basic unit of life.
Chapter 4 PSAT $ by October by October 11 Test 3- Tuesday October 14 over Chapter 4 and 5 DFA- Monday October 20 over everything covered so far (Chapters 1-5) Review on Thursday and Friday before 1. Explain
More information7.L.1.2 Plant and Animal Cells. Plant and Animal Cells
7.L.1.2 Plant and Animal Cells Plant and Animal Cells Clarifying Objective: 7.L.1.2 Compare the structures and functions of plant and animal cells; include major organelles (cell membrane, cell wall, nucleus,
More informationUNIT 3 CP BIOLOGY: Cell Structure
UNIT 3 CP BIOLOGY: Cell Structure Page CP: CHAPTER 3, Sections 1-3; HN: CHAPTER 7, Sections 1-2 Standard B-2: The student will demonstrate an understanding of the structure and function of cells and their
More informationHistory of Cell Theory. Organization of Life
History of Cell Theory Robert Hooke first observed cells while examining cork under the microscope (mid- 1600 s) Anton van Leeuwenhoek first observed microscopic organisms in pond water, as well as blood
More informationCell Organelles. a review of structure and function
Cell Organelles a review of structure and function TEKS and Student Expectations (SE s) B.4 Science concepts. The student knows that cells are the basic structures of all living things with specialized
More informationO.k., Now Starts the Good Stuff (Part II) Eukaryotic Cell Structure and Function
O.k., Now Starts the Good Stuff (Part II) Eukaryotic Cell Structure and Function Eukaryotic Cells These cells have membrane-bound structures called organelles. Cell processes occur in these organelles.
More information4.1 Cells are the Fundamental Units of Life. Cell Structure. Cells. Fundamental units of life Cell theory. Except possibly viruses.
Cells 4.1 Cells are the Fundamental Units of Life Fundamental units of life Cell theory All living things are composed of one or more cells. The cell is the most basic unit of life. All cells come from
More informationImportance of Protists
Protists Protists The kingdom Protista is a very diverse kingdom. Eukaryotes that are not classified as fungi, plants, or animals are classified as protists. However, even though they are officially in
More informationComponents of a functional cell. Boundary-membrane Cytoplasm: Cytosol (soluble components) & particulates DNA-information Ribosomes-protein synthesis
Cell (Outline) - Components of a functional cell - Major Events in the History of Earth: abiotic and biotic phases; anaerobic and aerobic atmosphere - Prokaryotic cells impact on the biosphere - Origin
More informationCells and Their Organelles
Mr. Ulrich Regents Biology Name:.. Cells and Their Organelles The cell is the basic unit of life. The following is a glossary of animal cell terms. All cells are surrounded by a cell membrane. The cell
More informationUnit 3: Cells. Objective: To be able to compare and contrast the differences between Prokaryotic and Eukaryotic Cells.
Unit 3: Cells Objective: To be able to compare and contrast the differences between Prokaryotic and Eukaryotic Cells. The Cell Theory All living things are composed of cells (unicellular or multicellular).
More informationThere are two commonly accepted theories for how eukaryotic cells evolved: infolding and endosymbiosis. Infolding
Protists Protists The kingdom Protista is a very diverse kingdom. Eukaryotes that are not classified as fungi, plants, or animals are classified as protists. However, even though they are officially in
More information2011 The Simple Homeschool Simple Days Unit Studies Cells
1 We have a full line of high school biology units and courses at CurrClick and as online courses! Subscribe to our interactive unit study classroom and make science fun and exciting! 2 A cell is a small
More informationNCERT solution for Fundamental Unit of Life
1 NCERT solution for Fundamental Unit of Life Question 1 Who discovered cells and how? An English Botanist, Robert Hooke discovered cells. In 1665, he used self-designed microscope to observe cells in
More informationBiology: Life on Earth
Teresa Audesirk Gerald Audesirk Bruce E. Byers Biology: Life on Earth Eighth Edition Lecture for Chapter 4 Cell Structure and Function Copyright 2008 Pearson Prentice Hall, Inc. Chapter 4 Outline 4.1 What
More informationHow do cell structures enable a cell to carry out basic life processes? Eukaryotic cells can be divided into two parts:
Essential Question How do cell structures enable a cell to carry out basic life processes? Cell Organization Eukaryotic cells can be divided into two parts: 1. Nucleus 2. Cytoplasm-the portion of the cell
More informationChapter 5: The Fundamental Unit of Life Science
Chapter 5: The Fundamental Unit of Life Science 1 Who discovered cells and how? An English Botanist, Robert Hooke discovered cells In 1665, he used self-designed microscope to observe cells in a cork slice
More informationThe Cell Notes 1 of 11
The Cell The basic unit of structure and function in living things The smallest units in living things The smallest units in living things that show the characteristics of life Organisms can be made of
More informationPre-lab homework Lab 4: The Cell
Pre-lab homework Lab 4: The Cell Lab Section: Name: After reading over the lab and chapter 5 in your textbook, answer these questions to be turned in at the beginning of the lab! 1. Define organelle 2.
More informationUnicellular vs. Multicellular Organisms Worksheet
Name Date Unicellular vs. Multicellular Organisms Worksheet Instructions for VIVED Science 1. Open the Plant Cell Structures and Animal (Human) Cell Structures sessions and follow the instructions. 2.
More informationChapter Life Is Cellular
Chapter 7 7-1 Life Is Cellular The Discovery of the Cell Anton van Leeuwenhoek used a single-lens microscope to observe tiny little organisms in pond water. The Discovery of the Cell In 1665, Robert Hooke
More informationBiology. Chapter 4. Cell Structure. Concepts and Applications 9e Starr Evers Starr
Biology Concepts and Applications 9e Starr Evers Starr Chapter 4 Cell Structure 2015 4.1 What Is a Cell? Cell theory Prior to the invention of the microscope, the existence of cells was unknown Mid-1600s:
More informationName Hour. Section 7-1 Life Is Cellular (pages )
Name Hour Section 7-1 Life Is Cellular (pages 169-173) Introduction (page 169) 1. What is the structure that makes up every living thing? The Discovery of the Cell (pages 169-170) 2. What was Anton van
More informationProkaryotic and Eukaryotic Cells. Structure and Function
Prokaryotic and Eukaryotic Cells Structure and Function In general microbes or microorganisms may be either prokaryotic (bacteria) or eukaryotic (protists, fungi, and some animals). However, there are
More informationHuman biology Cells: The Basic Units of Life. Dr. Rawaa Salim Hameed
Human biology Cells: The Basic Units of Life Dr. Rawaa Salim Hameed Reference Text book of human biology by John Kenneth Inglis 3 rd Ed (1985) Cells: The Basic Units of Life Cell theory Cell theory consists
More informationIntroduction to Botany
Introduction to Botany Alexey Shipunov Minot State University Lecture 13 Shipunov (MSU) Introduction to Botany Lecture 13 1 / 27 Outline 1 Questions and answers Quiz 2 Plant cell Cell boundaries Protein
More informationParamecium. Sub-Order Peniculina. Genus Paramecium
Paramecium Kingdom Animalia Phylum Protozoa Sub-Phylum Ciliophora Class Ciliata or Infusoria Sub-Class Holotricha Order Hymenostomatida Sub-Order Peniculina Family Paramecidae Genus Paramecium Introduction:
More informationCells to Tissues. Peter Takizawa Department of Cell Biology
Cells to Tissues Peter Takizawa Department of Cell Biology From one cell to ensembles of cells. Multicellular organisms require individual cells to work together in functional groups. This means cells
More informationBiology, 7e (Campbell) Chapter 6: A Tour of the Cell
Biology, 7e (Campbell) Chapter 6: A Tour of the Cell Chapter Questions 1) What limits the resolving power of a light microscope? A) the type of lens used to magnify the object under study B) the shortest
More informationAre these organisms. animals or not?
1 2 3 4 5 Are these organisms 6 7 8 animals or not? 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 Typical Animal Characteristics Eukaryotic Multicellular Ability to move Reproduce Obtain food (heterotrophic)
More informationCELL PART Expanded Definition Cell Structure Illustration Function Summary Location ALL CELLS DNA Common in Animals Uncommon in Plants Lysosome
CELL PART Expanded Definition Cell Structure Illustration Function Summary Location is the material that contains the Carry genetic ALL CELLS information that determines material inherited characteristics.
More informationCells. The Cell Theory. But what is a cell? Contributors to the Cell Theory:
Cells "Long ago it became evident that the key to every biological problem must finally be sought in the cell; for every living organism is, or at some time, has been a cell." E.B. Wilson The Cell Theory
More informationChemical aspects of the cell. Shape and structure of the cell
Chemical aspects of the cell Shape and structure of the cell Cellular composition https://www.studyblue.com/ 2 Cellular composition Set of videos with basic information: Cell characteristics: https://www.youtube.com/watch?v=urujd5nexc8
More informationChapter 4 A Tour of the Cell*
Chapter 4 A Tour of the Cell* *Lecture notes are to be used as a study guide only and do not represent the comprehensive information you will need to know for the exams. The Fundamental Units of Life Cells
More informationCells and Their Organelles
Cells and Their Organelles The cell is the basic unit of life. The following is a glossary of animal cell terms. All cells are surrounded by a cell membrane. The cell membrane is semipermeable, allowing
More informationThe Cell. What is a cell?
The Cell What is a cell? The Cell What is a cell? Structure which makes up living organisms. The Cell Theory l All living things are composed of cells. l Cells are the basic unit of life. l Cells come
More informationBiology I. Chapter 7
Biology I Chapter 7 Interest Grabber NOTEBOOK #1 Are All Cells Alike? All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells. 1.
More informationChapter 4 Cell Structure
Chapter 4 Cell Structure 4.2 What Is a Cell? Cells First observed in the microscope of Antoni van Leeuwenhoek First called cells by Robert Cooke Smallest unit of life Cell theory is a foundation of modern
More informationThe Discovery of Cells
The Discovery of Cells Microscope observations! General Cell & Organelle Discovery 1600s Observations made by scientists using more powerful microscopes in the 1800s led to the formation of the cell theory.
More information