DOCSLIB.ORG

Exp!Ore LAB SCIENCE

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Exp!Ore LAB SCIENCE exp!ore LAB SCIENCE CELL DIVISION What is cell division? All species pass on their genetic information by producing offspring. Both prokaryotes and eukaryotes use a process known as cell division to make new cells. Cell division is when a parent cell divides into two daughter cells. Prokaryotes use cell division to reproduce. Eukaryotes use cell division for growth and maintenance of cells, as well as for reproduction. What are the types of cell division? There are three main types of cell division: 1. Binary Fission – prokaryotes use this type of cell division to reproduce 2. The Cell Cycle/Mitosis – eukaryotes use this type of cell division to make new cells 3. Meiosis – this is a special type of cell division used by organisms that sexually reproduce exp!ore LAB SCIENCE CELL DIVISION IN Bacterial cell Origin of PROKARYOTES replication Centromere • Binary fission involves the replication of the prokaryotic chromosome to Centrioles produce new cells. • In bacteria, this chromosome is a circular double-stranded DNA molecule. Chromosomes • This circular DNA molecule constitutes the entire genome of the bacteria. • The reproduction of bacteria is clonal, Double-stranded Terminus of replication meaning each cell produced is an DNA (bacterial chromosome) identical copy of the parent cell. Spindle fibers exp!ore LAB SCIENCE BINARY FISSION Binary fission is the cellular reproduction mechanism used by single-celled prokaryotes, like bacteria. It occurs in five main steps: 1. Replication of the 2. Starting at the 3. The cell elongates 4. A new membrane 5. When the septum is circular bacterial DNA origin of replication, as the DNA is and cell wall begin to complete, the cell begins at the origin of the replication replicated. grow and form a pinches in two. Two replication. enzymes make copies septum at the midpoint daughter cells are of each strand of of the cell. formed, each DNA. The enzymes containing a bacterial continue until they DNA molecule. meet at the terminus of replication. exp!ore LAB SCIENCE THE CELL CYCLE Cell division in eukaryotes occurs in a cycle that consists of five phases. This cycle is called the cell cycle. Phases of the Cell Cycle: G1 (gap phase 1): this is the primary growth phase in which the cell prepares for DNA replication f S (synthesis): during this phase, the cell synthesizes a replica G1 S of its DNA f G2 Mitosis G2 (gap phase 2): this is the second growth phase in which Cytokinesis microtubules begin to form a spindle in order to prepare for separation of the replicated DNA f Mitosis: during this phase, the replicated DNA separates f Cytokinesis: during this phase, the cytoplasm separates, and two daughter cells are formed exp!ore LAB SCIENCE EUKARYOTIC Sister chromatids REPLICATION STRUCTURES Centromere • Nucleus: a structure located in the center of all eukaryotic cells that contains genetic Centrioles information in the form of chromosomes • Chromosomes: structures located in the nucleus of a cell; they contain the genetic information of the organism (DNA) and protein • Sister chromatids: two identical copies of a Chromosomes chromosome that are attached to each other by a centromere Nucleus • Centromere: a structure that connects two sister chromatids and serves as a point of attachment for spindle fibers • Spindle fibers: filaments that pull sister chromatids apart during cell division • Centrioles: structures that assist in the formation of spindle fibers exp!ore Spindle fibers LAB SCIENCE MITOSIS Mitosis is the cell division process used by eukaryotes in which a single cell divides into two identical daughter cells. Mitosis allows organisms to grow and replace old cells. Mitosis is divided into five phases: interphase, prophase, metaphase, anaphase, and telophase. Interphase Prophase Metaphase Anaphase Telophase The cell’s DNA The chromosomes The The The cell replicates. condense and the mitotic chromosomes chromosomes Microtubules elongates and spindles form. The nuclear align in the are pulled to the begins to divide begin to extend envelope also begins to center of the opposite sides into two from the disintegrate. cell. of the cell. centrioles. identical daughter cells. exp!ore LAB SCIENCE 1 PROPHASE I The chromosomes begin to condense and crossing over occurs. SEXUAL REPLICATION The spindle begins to form. VIA MEIOSIS 2 METAPHASE I The pairs of homologous chromosomes align at the equator of the cell. • Meiosis is separated into two parts – 3 ANAPHASECentromere I Meiosis I and Meiosis II. The homologous pairs of chromosomes are pulled apart. • Each part consists of prophase, metaphase, I MEIOSIS 4 CentriolesTELOPHASE I & CYTOKINESIS anaphase, and telophase. The separated homologues cluster at each end of the cell. The cell is split, forming two new cells, each with half the number of chromosomes as the original • A key feature of Meiosis is the crossing cell. over that occurs in Prophase I. 5 PROPHASE II • Crossing over is what gives us genetic A new spindle forms in each cell and the nuclear envelope breaks down. Chromosomes variation. 6 METAPHASE II • Homologues are separated during Chromosomes are joined at the centromere and align at the equator of the cell. 7 Meiosis I and sister chromatids are ANAPHASE II The sister chromatids are pulled apart. separated during Meiosis II. II MEIOSIS 8 TELOPHASE II & CYTOKINESIS • The steps of Meiosis are listed to the The separated sister chromatids cluster at each end of the cell. The cells are both split, forming four genetically diverse cells. right. Spindle fibers exp!ore LAB SCIENCE MEIOSIS Telophase I Telophase II Interphase Prophase I Metaphase I Anaphase I Prophase II Metaphase II Anaphase II & Cytokinesis & Cytokinesis exp!ore LAB SCIENCE REFERENCES Mason, K. Understanding Biology. McGraw-Hill Education; 1st edition, 2014. exp!ore LAB SCIENCE.
Load more

Recommended publications
  • Mobile Genetic Elements in Streptococci
    Curr. Issues Mol. Biol. (2019) 32: 123-166. DOI: https://dx.doi.org/10.21775/cimb.032.123 Mobile Genetic Elements in Streptococci Miao Lu#, Tao Gong#, Anqi Zhang, Boyu Tang, Jiamin Chen, Zhong Zhang, Yuqing Li*, Xuedong Zhou* State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China. #Miao Lu and Tao Gong contributed equally to this work. *Address correspondence to: [email protected], [email protected] Abstract Streptococci are a group of Gram-positive bacteria belonging to the family Streptococcaceae, which are responsible of multiple diseases. Some of these species can cause invasive infection that may result in life-threatening illness. Moreover, antibiotic-resistant bacteria are considerably increasing, thus imposing a global consideration. One of the main causes of this resistance is the horizontal gene transfer (HGT), associated to gene transfer agents including transposons, integrons, plasmids and bacteriophages. These agents, which are called mobile genetic elements (MGEs), encode proteins able to mediate DNA movements. This review briefly describes MGEs in streptococci, focusing on their structure and properties related to HGT and antibiotic resistance. caister.com/cimb 123 Curr. Issues Mol. Biol. (2019) Vol. 32 Mobile Genetic Elements Lu et al Introduction Streptococci are a group of Gram-positive bacteria widely distributed across human and animals. Unlike the Staphylococcus species, streptococci are catalase negative and are subclassified into the three subspecies alpha, beta and gamma according to the partial, complete or absent hemolysis induced, respectively. The beta hemolytic streptococci species are further classified by the cell wall carbohydrate composition (Lancefield, 1933) and according to human diseases in Lancefield groups A, B, C and G.
    [Show full text]
  • Transposable Elements Drive Reorganisation of 3D Chromatin
    bioRxiv preprint doi: https://doi.org/10.1101/523712; this version posted January 17, 2019. 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 4.0 International license. Transposable elements drive reorganisation of 3D chromatin during early embryogenesis Kai Kruse1, Noelia Díaz1, §, Rocio Enriquez-Gasca1, §, Xavier Gaume2, 4, Maria-Elena Torres-Padilla2, 3 and Juan M. Vaquerizas1, * 1. Max Planck Institute for Molecular Biomedicine, Roentgenstrasse 20, 48149 Muenster, Germany. 2. Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, Marchioninistraße 25, 81377 Munich, Germany. 3. Faculty of Biology, Ludwig Maximilians Universität, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany. 4. Present address: Cancer Research Center of Lyon, 28 Rue Laennec, Lyon 69008, France. §. These authors have contributed equally to this work. *. Correspondence to J.M.V. ([email protected], @vaquerizasjm) Keywords: Chromosome conformation capture; low-input Hi-C; early embryonic development; totipotency; transposable elements; MERVL; TAds; 2-cell embryo; 2-cell-like cells; zygotic genome activation; CAF-1; dux. Transposable elements are abundant genetic components of eukaryotic genomes with important regulatory features affecting transcription, splicing, and recombination, among others. Here we demonstrate that the Murine Endogenous Retroviral Element (MuERV-L/MERVL) family of transposable elements drives the 3D reorganisation of the genome in the early mouse embryo. By generating Hi-C data in 2-cell-like cells, we show that MERLV elements promote the formation of insulating domain boundaries through- out the genome in vivo and in vitro.
    [Show full text]
  • Review Cell Division from a Genetic Perspective
    REVIEW CELL DIVISION FROM A GENETIC PERSPECTIVE LELAND H. HARTWELL From the Department of Genetics, University of Washington, Seattle, Washington 98195 Recently, a number of laboratories have begun to incubation at the restrictive condition for that study mutant cells that are defective in specific mutation, whereas mutants with defects in one of stages of the eukaryotic cell cycle. The long-range the continuously required functions will arrest at goals of this work are to identify the genes that the restrictive temperature with cells at a variety code for division-related proteins, to define the of positions in the cell cycle. roles that these gene products play and to investi- Classes of mutants may be distinguished from gate the hierarchies of order that assure their one another and the roles of their products delim- coordinated activity. It is my intent in this brief ited by determining the stage-specific event at review to discuss the strategies employed in this which they arrest. It is convenient to have a genetic approach and to enumerate some of the designation for the first landmark of the cell cycle new conclusions that have come to light. A recent that is blocked in a particular mutant, and I shall review on the genetics of meiosis (2) complements call it the diagnostic landmark for that mutant. this review on mitosis. Mutants of Saccharomyces cerevisiae have been identified that have diagnostic landmarks at spin- MUTANTS dle pole body (SPB) duplication, SPB separation, Mutations that inactivate gene products essential initiation of DNA synthesis, DNA replication, for division would be lethal.
    [Show full text]
  • Cell Division and Cycle
    Name: _______________________ Date:_____________ Period_________ Subject: ________ Cell Division and Cycle Read the phase to answer the questions 1 through 10. Living organisms are constantly making new cells. They make new cells in order to grow and also to replace old dead cells. The process by which new cells are made is called cell division. Cell division is occurring all the time. Around two trillion cell divisions occur in the average human body every day! Types of Cell Division There are three main types of cell division: binary fission, mitosis, and meiosis. Binary fission is used by simple organisms like bacteria. More complex organisms gain new cells by either mitosis or meiosis. Mitosis Mitosis is used when a cell needs to be replicated into exact copies of itself. Everything in the cell is duplicated. The two new cells have the same DNA, functions, and genetic code. The original cell is called the mother cell and the two new cells are called daughter cells. The full process, or cycle, of mitosis is described in more detail below. Examples of cells that are produced through mitosis include cells in the human body for the skin, blood, and muscles. Cell Cycle for Mitosis Cells go through different phases called the cell cycle. The "normal" state of a cell is called the "interphase". The genetic material is duplicated during the interphase stage of the cell. When a cell gets the signal that it is to duplicate, it will enter the first state of mitosis called the "prophase". Prophase - During this phase the chromatin condenses into chromosomes and the nuclear membrane and nucleolus break down.
    [Show full text]
  • Mitosis Vs. Meiosis
    Mitosis vs. Meiosis In order for organisms to continue growing and/or replace cells that are dead or beyond repair, cells must replicate, or make identical copies of themselves. In order to do this and maintain the proper number of chromosomes, the cells of eukaryotes must undergo mitosis to divide up their DNA. The dividing of the DNA ensures that both the “old” cell (parent cell) and the “new” cells (daughter cells) have the same genetic makeup and both will be diploid, or containing the same number of chromosomes as the parent cell. For reproduction of an organism to occur, the original parent cell will undergo Meiosis to create 4 new daughter cells with a slightly different genetic makeup in order to ensure genetic diversity when fertilization occurs. The four daughter cells will be haploid, or containing half the number of chromosomes as the parent cell. The difference between the two processes is that mitosis occurs in non-reproductive cells, or somatic cells, and meiosis occurs in the cells that participate in sexual reproduction, or germ cells. The Somatic Cell Cycle (Mitosis) The somatic cell cycle consists of 3 phases: interphase, m phase, and cytokinesis. 1. Interphase: Interphase is considered the non-dividing phase of the cell cycle. It is not a part of the actual process of mitosis, but it readies the cell for mitosis. It is made up of 3 sub-phases: • G1 Phase: In G1, the cell is growing. In most organisms, the majority of the cell’s life span is spent in G1. • S Phase: In each human somatic cell, there are 23 pairs of chromosomes; one chromosome comes from the mother and one comes from the father.
    [Show full text]
  • Microbial Growth
    7 Microbial Growth 1 7.1 Reproductive strategies 1. Describe binary fission as observed in bacteria and archaea 2. Compare the three reproductive strategies used by bacteria other than binary fission 2 Reproductive Strategies • The reproductive strategies of eukaryotic microbes – asexual and sexual, haploid or diploid • Bacteria and Archaea – haploid only, asexual - binary fission, budding, filamentous – all must replicate and segregate the genome prior to division 3 4 7.2 Bacterial cell cycle 1. Summarize the two major events in a typical bacterial cell cycle 2. State the functions of cytoskeletal proteins in a typical bacterial cell cycle and in determining cell shape 5 Bacterial Cell Cycle • Cell cycle is sequence of events from formation of new cell through the next cell division – most bacteria divide by binary fission • Two pathways function during cycle – DNA replication and partition – cytokinesis 6 Chromosome Replication and Partitioning - 1 • Most bacterial chromosomes are circular • Single origin of replication – site at which replication begins • Terminus – site at which replication is terminated, located opposite of the origin • Replisome – group of proteins needed for DNA synthesis • DNA replication proceeds in both directions from the origin • Origins move to opposite ends of the cell 7 8 Chromosome Partitioning • Replisome pushes, or condensation of, daughter chromosomes to opposite ends • MreB (murein cluster B) – an actin homolog, plays role in determination of cell shape as spiral inside cell periphery, and chromosome
    [Show full text]
  • Chromochloris Zofingiensis (Chlorophyceae) Divides By
    biology Article Chromochloris zofingiensis (Chlorophyceae) Divides by Consecutive Multiple Fission Cell-Cycle under Batch and Continuous Cultivation Idan Koren, Sammy Boussiba , Inna Khozin-Goldberg and Aliza Zarka * Microalgal Biotechnology Laboratory, French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus, Midreshet Ben-Gurion 8499000, Israel; [email protected] (I.K.); [email protected] (S.B.); [email protected] (I.K.-G.) * Correspondence: [email protected] Simple Summary: Microalgae are plant-like micro-organisms naturally found in fresh and marine water environments, inhabiting a vast range of ecosystems. They capture light energy through photosynthesis and convert low energy inorganic compounds (carbon dioxide and water) into high energy complex organic compounds, such as carbohydrates and fats. Chromochloris zofingiensis is a unicellular microalga currently under intensive research, due to its ability to produce high value pharmaceutical and nutritional pigments. Understanding its growth characteristics is crucial for the establishment of an efficient commercial production of those pigments from this alga. Thus, we have developed a method to stain the nucleus of the alga which enabled us to follow the division pattern under commonly used cultivation methods. We found that C. zofingiensis cells conduct consecutive Citation: Koren, I.; Boussiba, S.; DNA synthesis and divisions of the nucleus to produce 8 or 16 nuclei before it divides into 8 or Khozin-Goldberg, I.; Zarka, A. 16 daughter cells, respectively. Under high light illumination, the whole process lasts several days, Chromochloris zofingiensis through which cells grow during the light period and divide during the dark period.
    [Show full text]
  • Cell Growth and Reproduction Lesson 6.2: Chromosomes and DNA Replication
    Chapter 6: Cell Growth and Reproduction Lesson 6.2: Chromosomes and DNA Replication Cell reproduction involves a series of steps that always begin with the processes of interphase. During interphase the cell’s genetic information which is stored in its nucleus in the form of chromatin, composed of both mitotic and interphase chromosomes molecules of protein complexes and DNA strands that are loosely coiled winds tightly to be replicated. It is estimated that the DNA in human cells consists of approximately three billion nucleotides. If a DNA molecule was stretched out it would measure over 20 miles in length and all of it is stored in the microscopic nuclei of human cells. This lesson will help you to understand how such an enormous amount of DNA is coiled and packed in a complicated yet organized manner. During cell reproduction as a cell gets ready to divide the DNA coils even more into tightly compact structures. Lesson Objectives • Describe the coiled structure of chromosomes. • Understand that chromosomes are coiled structures made of DNA and proteins. They form after DNA replicates and are the form in which the genetic material goes through cell division. • Discover that DNA replication is semi-conservative; half of the parent DNA molecule is conserved in each of the two daughter DNA molecules. • Outline discoveries that led to knowledge of DNA’s structure and function. • Examine the processes of DNA replication. Vocabulary • centromere • double helix • Chargaff’s rules • histones • chromatid • nucleosomes • chromatin • semi-conservative DNA replication • chromosome • sister chromatids • DNA replication • transformation Introduction In eukaryotic cells, the nucleus divides before the cell itself divides.
    [Show full text]
  • The Obscure World of Integrative and Mobilizable Elements Gérard Guédon, Virginie Libante, Charles Coluzzi, Sophie Payot-Lacroix, Nathalie Leblond-Bourget
    The obscure world of integrative and mobilizable elements Gérard Guédon, Virginie Libante, Charles Coluzzi, Sophie Payot-Lacroix, Nathalie Leblond-Bourget To cite this version: Gérard Guédon, Virginie Libante, Charles Coluzzi, Sophie Payot-Lacroix, Nathalie Leblond-Bourget. The obscure world of integrative and mobilizable elements: Highly widespread elements that pirate bacterial conjugative systems. Genes, MDPI, 2017, 8 (11), pp.337. 10.3390/genes8110337. hal- 01686871 HAL Id: hal-01686871 https://hal.archives-ouvertes.fr/hal-01686871 Submitted on 26 May 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. Distributed under a Creative Commons Attribution| 4.0 International License G C A T T A C G G C A T genes Review The Obscure World of Integrative and Mobilizable Elements, Highly Widespread Elements that Pirate Bacterial Conjugative Systems Gérard Guédon *, Virginie Libante, Charles Coluzzi, Sophie Payot and Nathalie Leblond-Bourget * ID DynAMic, Université de Lorraine, INRA, 54506 Vandœuvre-lès-Nancy, France; [email protected] (V.L.); [email protected] (C.C.); [email protected] (S.P.) * Correspondence: [email protected] (G.G.); [email protected] (N.L.-B.); Tel.: +33-037-274-5142 (G.G.); +33-037-274-5146 (N.L.-B.) Received: 12 October 2017; Accepted: 15 November 2017; Published: 22 November 2017 Abstract: Conjugation is a key mechanism of bacterial evolution that involves mobile genetic elements.
    [Show full text]
  • U6-Life-Cycle-Background.Pdf
    UNIT 6: LIFE CYCLE CORAL REEF ECOLOGY CURRICULUM This unit is part of the Coral Reef Ecology Curriculum that was developed by the Education Department of the Khaled bin Sultan Living Oceans Foundation. It has been designed for secondary school students, but can be adapted for other uses. The entire curriculum can be found online at lof.org/CoralReefCurriculum. Author and Design/Layout: Amy Heemsoth, Director of Education Editorial assistance provided by: Andrew Bruckner, Ken Marks, Melinda Campbell, Alexandra Dempsey, and Liz Rauer Thompson Illustrations by: Amy Heemsoth Cover Photo: ©Michele Westmorland/iLCP ©2014 Khaled bin Sultan Living Oceans Foundation. All rights reserved. Unless otherwise noted, photos are property of the Khaled bin Sultan Living Oceans Foundation. The Khaled bin Sultan Living Oceans Foundation and authors disclaim any liability for injury or damage related to the use of this curriculum. These materials may be reproduced for education purposes. When using any of the materials from this curriculum, please include the following attribution: Khaled bin Sultan Living Oceans Foundation Coral Reef Ecology Curriculum www.lof.org The Khaled bin Sultan Living Oceans Foundation (KSLOF) was incorporated in California as a 501(c)(3), public benefit, Private Operating Foundation in September 2000. The Living Oceans Foundation is dedicated to providing science-based solutions to protect and restore ocean health through research, outreach, and education. The educational goals of the Khaled bin Sultan Living Oceans Foundation and
    [Show full text]
  • Coordinating DNA Replication Initiation with Cell Growth
    Proc. Natl. Acad. Sci. USA Vol. 93, pp. 12206-12211, October 1996 Biochemistry Coordinating DNA replication initiation with cell growth: Differential roles for DnaA and SeqA proteins (Escherichia coli/initiation mass) ERIK BOYE*t, TROND STOKKE*, NANCY KLECKNERt, AND KIRSTEN SKARSTAD* *Departments of Biophysics and Cell Biology, Institute for Cancer Research, Montebello, 0310 Oslo, Norway; and tDepartment of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 Contributed by Nancy Kleckner, July 25, 1996 ABSTRACT We describe here the development of a new DnaA recognizes oriC specifically and, together with accessory approach to the analysis of Escherichia coli replication con- proteins, promotes the formation of an open complex which trol. Cells were grown at low growth rates, in which case the permits loading of the DnaB helicase and priming of DNA bacterial cell cycle approximates that of eukaryotic cells with replication (4). A second component, SeqA, has been identi- Gl, S, and G2 phases: cell division is followed sequentially by fied genetically as a negative modulator of the initiation a gap period without DNA replication, replication ofthe single process (5). Biochemical data suggest that SeqA mediates its chromosome, another gap period, and finally the next cell effects by binding to oriC prior to initiation (6). division. Flow cytometry of such slowly growing cells reveals The most detailed molecular models of initiation control in the timing of replication initiation as a function of cell mass. E. coli have focused on the DnaA protein. The amount of The data show that initiation is normally coupled to cell DnaA protein per origin (7), the activity of DnaA protein per physiology extremely tightly: the distribution ofindividual cell cell (8), or the concentration of DnaA (9) have been proposed masses at the time of initiation in wild-type cells is very to trigger initiation of DNA replication.
    [Show full text]
  • Genes Controlling Essential Cell-Cycle Functions in Drosophila Melanogaster
    Downloaded from genesdev.cshlp.org on October 3, 2021 - Published by Cold Spring Harbor Laboratory Press Genes controlling essential cell-cycle functions in Drosophila melanogaster Maurizio Gatti I and Bruce S. Baker 2 ~Dipartimento de Genetica e Biologia Molecolare, Universit/l di Roma 'La Sapienza', 00185 Roma, Italy; 2Department of Biological Sciences, Stanford University, Stanford, California 94305 USA On the basis of the hypothesis that mutants in genes controlling essential cell cycle functions in Drosophila should survive up to the larval-pupal transition, 59 such 'late lethals' were screened for those mutants affecting cell division. Examination of mitosis in brain neuroblasts revealed that 30 of these lethals cause disruptions in mitotic chromosome behavior. These mutants identify genes whose wild-type functions are important for: (1) progression through different steps of interphase, (2) the maintenance of mitotic chromosome integrity, (3) chromosome condensation, (4) spindle formation and/or function, and (5) completion of cytokinesis or completion of chromosome segregation. The presence of mitotic defects in late lethal mutants is correlated tightly with the presence of defective imaginal discs. Thus, the phenotypes of late lethality and poorly developed imaginal discs are together almost diagnostic of mutations in essential cell-cycle functions. The terminal phenotypes exhibited by these Drosophila mitotic mutants are remarkably similar to those observed in mammalian cell-cycle mutants, suggesting that these diverse organisms use a common genetic logic to regulate and integrate the events of the cell cycle. [Key Words: Cell-cycle mutants; Drosophila; mitosis] Received November 30, 1988; revised version accepted February 7, 1989. The exquisitely precise cyclic changes that eukaryotic review, see Simchen 1978; Ling 1981; Oakley 1981; chromosomes and cells undergo during mitotic and Wissmger and Wang 1983; Marcus et al.
    [Show full text]