Ppt on polytene chromosomes in drosophila

The Nucleus 10. 10 The Nucleus The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm The Organization of Chromosomes Nuclear Bodies.

of Chromosomes This organization was first suggested in 1885 and confirmed in 1984 by studies of polytene chromosomes in Drosophila salivary glands. Each chromosome was found to occupy a discrete region of the nucleus, called a chromosome territory. Figure 10.16 Chromosome organization (Part 1) Figure 10.16 Chromosome organization (Part 2) Figure 10.17 Organization of Drosophila chromosomes (Part 1) Figure 10.17 Organization of Drosophila chromosomes (Part 2) The Organization of Chromosomes In situ/


Chapter 5 DNA and Chromosomes Essential Cell Biology FOURTH EDITION Copyright © Garland Science 2014 Alberts Bray Hopkin Johnson Lewis Raff Roberts Walter.

that are segregated to daughter cells during cell division. Fig. 5-1 T. H. Morgan used Drosophila genetics and the giant chromosomes from their salivary glands to show that chromosomes contain the genetic information. Drosophila genetics Giant polytene chromosomes In larval salivary glands -1920s DNA Component of Chromosomes Contains Genetic Information for Virulence Purified DNA (not protein) from heat-killed S strain also transformed. Fig. 5-3 DNA/


The chromatin Yin / Yang

in Drosophila as regulators of Homeotic genes, responsible for specification of the body plan, they also regulate many other targets involved in cell differentiation and proliferation PcG proteins silence genes, trxG proteins activate them Conserved throughout evolution In / Chromatin PcG proteins bind to specific DNA elements, named PREs 9-98 Bound by PcG proteins in vivo (in polytene chromosomes and by cross-linking experiments) Binding leads to maintenance of PcG-dependent repression of reporter genes /


LECTURE 04: CHROMOSOMAL BASIS OF INHERITANCE I Fhow do we know that genes are parts of chromosomes? Fhow are they arranged on chromosomes? Fare chromosomes.

” F FISH (fluorescent in situ hybridization) F telomere-specific DNA F tandem arrays of non-coding sequence F overcomes replication problem... more on this later CHROMOSOMES - TOPOGRAPHY Fhuman nucleus, metaphase, n = 23, Giemsa stain Fbanding patterns - consistent, chromosome-specific FG-dark & G-light... significance of bands? CHROMOSOMES - TOPOGRAPHY F Drosophila chromosomes F centromeres F telomeres F euchromatin F heterochromatin F polytene chromosomes F chromocenter CHROMOSOMES - TOPOGRAPHY why is/


Genetics of Axis Specification in Drosophila Part 1 - Basics of Drosophila Embryogenesis Gilbert - Chapter 9.

REALLY tiny! Embryos are quite complex Larval stages, metamorphosis Power of Genetics Polytene chromosomes Ability to manipulate DNA, RNA, Protein made Drosophila a usable developmental bio model organism Revolutionized the study of development, by providing/genes Segment polarity genes Homeotic selector genes Genetic Screen for Genes involved in Drosophila Development Nusslien-Volhard, Wieschaus Fed mutagens to Drosophila Then breed until mutation is homozygous recessive Examined embryos for patterning /


Controls Over Genes Chapter 14. Gene Control Which genes are being expressed in a cell depends upon: The type of cell Internal chemical conditions External.

-10 percent of their genes at any given time The remaining genes are selectively expressed Polytene Chromosomes Occur in salivary glands of midge larvae Consist of multiple DNA molecules Can produce multiple copies of transcripts Chromosome Puff Portion of the polytene chromosome in which the DNA has loosened up to allow transcription Appears in response to ecdysone Translation of transcripts from puffed region produces protein components of saliva/


Chromatin Structure & Genome Organization. Overview of Chromosome Structure Nucleosomes –~200 bp DNA in 120 Å diameter coil –3.4 Å /bp x 200 = 680 Å –680/120.

of DNA to which scaffold proteins bind –LCR DNA elements known to regulate expression of large regions of DNA containing multiple genes –Boundary elements scs elements flank puffs in Drosophila polytene chromosomes Chromosome Loops Chromosome Structure: The Metaphase Chromosome Centromeres DNA sequence –Repetitive DNA elements –Constitutive heterochromatin Protein components –CENP-A, B & C Centromeres Repetitive DNA of mammalian centromeres –  satellite DNA –171 bp unit –Several specific unit/


VII. DNA and Genome Structure A. Search for the Genetic Information B. Determining DNA Structure C. Chromosome Structure.

coding sequences. These can be seen in a ‘polytene chromosome’ VII. DNA and Genome Structure A. Search for the Genetic Information B. Determining DNA Structure C. Chromosome Structure 1. Eukaryotic Chromosomes 2. Bacterial Chromosomes VII. DNA and Genome Structure A./to be sequenced. Arabidopsis thaliana115,409,949~28,000 a flowering plant (angiosperm) See note.angiospermSee note. Drosophila melanogaster122,653,97713,379the "fruit fly" Anopheles gambiae278,244,06313,683Mosquito vector of malaria. Rice3.9 x/


Chromosome Mutation Relocation of Genetic Material - how do chromosome rearrangements occur? - how can we detect them - what are their genetic and phenotypic.

NF1 gene responsible for neurofibromatosis - used rearrangement breakpoint mapping Create strains carrying duplication or deletions –Small inversions or translocations can result in viable progeny Balancer Chromosomes in Drosophila –Prevent recombination anywhere on a chromosome in a inversion heterozygote Deletions Drosophila Polytene Chromosomes allow deletion loops to be visualized Using multigene deletions for mapping the location of point mutants Human diseases associated with deletions Conceptions/


Conservation of Hawaiian Drosophila using phylogenetic, ecological and population genetic data. Patrick M. O’Grady University of California, Berkeley.

old are the endemic Hawaiian Drosophilidae? 15my 16my 9my 21my 61 100 99 Species group relationships in Hawaiian Drosophila lineage agree with previous work. 100 antopocerus/ modified tarsus picture wing/ nudidrosophila modified mouthpart haleakalae/ –Taxonomy not well understood. –Difficult to work with (little known of their ecology, not culturable in the laboratory, polytene chromosomes are not amenable to study). –Historical distribution and abundance data not available. Other groups? Loss of/


Primer on Annotation of Drosophila Genes GEP Workshop – January 2016 Wilson Leung and Chris Shaffer.

Four Genomes Paper New species sequenced by modENCODE Phylogenetic tree produced by Thom Kaufman as part of the modENCODE project Manuscript in progress Muller element nomenclature Schaeffer SW et al, 2008. Polytene Chromosomal Maps of 11 Drosophila Species: The Order of Genomic Scaffolds Inferred From Genetic and Physical Maps. Genetics. 2008 Jul;179(3):1601-55 X2L2R3L3R4 X45326 Gene structure nomenclature Gene span Primary/


Gene expression and regulation.  cis-acting Referring to a regulatory sequence in DNA (e.g., enhancer, promoter) that can control a gene only on the.

effects ) Schematic diagram summarizing the properties of insulators Mechanism of imprinting of the mouse Igf2 gene Localization of a Drosophila insulator-binding protein on polytene chromosomes Response elements sequence usually located a short distance upstream of promoters that makes gene expression responsive to some chemical in the cellular environment Consensus response element (RE) Response to:Protein factor which recognizes RE (T/G)(T/A/


Steroid Control of Leg Development in Drosophila Craig T. Woodard Mount Holyoke College.

Cell Death Gas bubble translation Beginning of imaginal disc morphogenesis Third Instar Larva Leg Disc Elongation and Eversion Adult Stages in Drosophila Leg Development Embryonic Stage Leg imaginal discs patterned Puparium Formation (Beginning of Metamorphosis = 0-Hrs. APF) Ecdysone /F1 antibodies shows ßFTZ-F1 protein bound to the BR-C, E74A, E75A and E93 loci in prepupal salivary gland polytene chromosomes. Ectopic expression of ßFTZ-F1 provides E93 with the competence to respond to the late larval /


In vivo protein-DNA interactions Giacomo Cavalli UE Méthodologie, 11 April, 2014 Institut de Génétique Humaine, CNRS Montpellier, France.

-dependent chromatin remodeling PcG and trxG proteins associate to multiple genomic loci Polytene chromosome staining shows around 100 bands for each PcG protein Genome-wide identification /drosophila gypsy retrotransposon ● This sequence contains 12 binding sites for the Su(Hw) protein, that is required for insulator function Insulator bypass model The gypsy insulator Domain A Insulating proteins Gerasimova et al, Mol. Cell, 2000 Model of nuclear chromosomal architecture based on insulators interaction Ins/


Steroid Control of Leg Development in Drosophila Craig T. Woodard Mount Holyoke College.

Body Parts Destruction of Larval body Parts by Programmed Cell Death Gas bubble translation Beginning of imaginal disc morphogenesis Stages in Drosophila Leg Development Embryonic Stage Leg imaginal discs patterned Puparium Formation (Beginning of Metamorphosis = 0-Hrs. APF) Ecdysone /F1 antibodies shows ßFTZ-F1 protein bound to the 2B5, 74EF, 75B and 93F puff loci in prepupal salivary gland polytene chromosomes. Ectopic expression of ßFTZ-F1 provides E93 with the competence to respond to the late larval /


Mammalian Cytogenetics Chromosome structure & karyotype Gene 405: Mammalian Genetics Fall 2002 17 September, 2002.

) Homo sapiens (human)46 Mus musculus (house mouse)40 Zea mays(corn or maize)20 Drosophila melanogaster (fruit fly)8 Xenopus laevis (South African clawed frog)36 Caenorhabditis elegans (microscopic roundworm)/ in offspring abnormal gamete formation Polytene Chromosomes Giant chromosomes - dipteran Begin as normal chromosomes Repeated rounds of DNA replication (endoreplication); & no cell division Become large banded chromosomes Centromere – no endoreplication Bundle in a mass - chromocenter Found in larvae/


Rein et al., 2002 Current Biology The mushroom bodies (MBs) in the adult Drosophila brain.

EcR-B ecdysone receptor for mushroom body neuronal remodeling in Drosophila Zheng et al., Cell (2003) 112:303-315 TGF-  signaling activates steroid hormone receptor expression during neuronal remodeling in the Drosophila brain Boulanger et al., Nature Neuroscience (2011)/-f1 + PUP ECR-B1  neuron pruning + ftz-f1 - FTZ-F1 is binding the polytene chromosome band 42 A (EcR) (Lavorgna et al PNAS 1993) - at 10h APF reduced expression of EcR in hs-ftz-f1 RNAi (Lam and Thummel Cu.Bio. 2000) HYPOTHESIS 1 2 EcR-B1 /


Human Karyotypes and Chromosome Behavior

= abnormal pairing of trisomic chromosomes in cell division Univalent = extra chromosome in trisomy is unpaired in cell division Sex Chromosome Aneuploidies trisomy-X=47, XXX (female) double-Y=47, XYY (male) Klinefelter Syndrome=47, XXY (male, sterile) Turner Syndrome=45, X (female, sterile) Fragile-X syndrome= X chromosome instability resulting from high copy number of trinucleotide repeat Chromosome Deletions Deletions = missing chromosome segment Polytene chromosomes of Drosophila can be used to map/


Chapter 8 Human Karyotypes and Chromosome Behavior

’s syndrome increases with Mother’s age Pairing and segregation of 3 homologous chromosomes in meiosis I This kind of chromosome pairing occurs in trisomics (2n+1) or triploids (3n) Mapping the deletion of part of a chromosome segment by testcrosses and uncovering of recessive genes Mapping of genes in Drosophila using overlapping deletions and polytene chromosomes Unequal crossing over of misaligned repeat sequences leads to gain or loss/


Chapter 8 Human Karyotypes and Chromosome Behavior Jones and Bartlett Publishers © 2005.

of a gene are required for normal gene function, only havinog one is a problem. ‘Cri du Chat’ syndrome in humans: –Deficiency of a part of chromosome 5 Mapping the deletion of part of a chromosome segment by testcrosses and uncovering of recessive genes Mapping of genes in Drosophila using overlapping deletions and polytene chromosomes Duplications Mutations can produce an extra copy of a part of a/


Chromosomes Cytogenetics: study which links chromosome variations to specific traits Chromosome: Dark heterochromatin (repetitive DNA) Light euchromatin.

narrow face with protruding chin, enlarged ears  Increased testicular size (gynecomastia)  Gene = FMR1 (sequence of 3 nucleotides repeated many times)  Link between an autosomal fragile site and lung cancer Specialized Chromosomes Polytene Chromosomes: salivary, rectal, midgut Can be seen in interphase Individual bands called chromomeres Undergo uncoiling (puff) in Drosophila Lampbrush Chromosomes: meiotic chromosomes In vertebrate oocytes and insect spermatocytes


5 Human Chromosomes and Chromosome Behavior

= abnormal pairing of trisomic chromosomes in cell division Univalent = extra chromosome in trisomy is unpaired in cell division Fig. 5.13 Sex Chromosome Aneuploidies An extra X or Y chromosome usually has a relatively mild effect Trisomy-X = 47, XXX (female) Double-Y = 47, XYY (male) Klinefelter Syndrome = 47, XXY (male, sterile) Turner Syndrome = 45, X (female, sterile) Chromosome Deletions Deletions = missing chromosome segment Polytene chromosomes of Drosophila can be used to/


LECTURE CONNECTIONS 11 | Chromosome Structure © 2009 W. H. Freeman and Company and Transposable Elements.

structure: when nucleosomes fold on themselves to form a dense, tightly packed structure. Changes in Chromatin Structure Polytene chromosome: giant chromosomes found in certain tissues of Drosophila and some other organisms. Chromosomal puffs: localized swellings of the chromosome. Chromatin have a relaxed structure. DNase I sensitivity is correlated with the transcription of globin genes in erythroblasts of chick embryos. The U gene encodes embryonic hemoglobin; the αD and αA/


Chromatin Structure and Function BSCI 420. Chromatin is the complex of DNA and proteins that comprise eukaryotic chromosomes. 2 classes of chromatin proteins:

view the structure of active vs. inactive regions. A. Lampbrush chromosomes. Paired meiotic chromosomes that partially condense and pause during a long meiotic prophase to synthesize RNAs & proteins to be stored in the egg for early development. Phase-contrast and fluorescent micrographs of lampbrush chromosomes B. Polytene chromosomes of Drosophila Have replicated DNA 10X -> 1024 copies of chromosome side by side without separation by mitosis. Bands are chromatin/


DNA Replication Lecture 10 Dr. Attya Bhatti. Mechanism of DNA replication In E-Coli In the late 1950s, Arthur Kornberg successfully identified and purified.

, replication proceeds from multiple points of origin. Replication appears to begin at several different sites on eukaryotic chromosomes. Eukaryotic origins of replication Figure: Replication pattern in a Drosophila polytene chromosome revealed by autoradiography. Several points of replication are seen within a single chromosome, as indicated by arrows. Yet there is no firm proof that these regions are indeed different starting points on a single DNA molecule/


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

The Dosage Compensation Complex in Drosophila from Gilfillan et al., FEBS Lett. 567, 8 (2004) SXL in females prevents MSL2 translation MSL2 in males stabilizes roX, MSL1, and MSL3 DCC binds to high affinity sites on X chromosome DCC spreads to /) DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates by a Semiconservative Mechanism Grow cells in 15 N and transfer to 14 N/


Conjugation and autogamy in ciliated protozoans Paul R. Earl Facultad de Ciencias Biológicas Universidad Autónoma de Nuevo León San Nicolás,

degraded unless needed to salvage a malfunctioning new MA. One of 2 MI in the 1st exconjugant is eliminated so that the 2 nd excongugant regains 1 MI + 1 MA. Soon after mitosis, chromosomes within the nucleus are destined to differentiate, undergoing multiple rounds of replication to form polytene chromosomes. The chromosomes are radically fragmented to minichromosomes, telomeres are added to sequences of the MDSs/


Protein Complexes in S. cerevisiae and E. coli A Focus on Transcription NIH April 7, 2003.

E. coli RecBCD – Exonuclease V λ Gam - Temperature sensitive cI repressor – inactive at 42°C CHROMOSOMAL ORF Identification of Protein Complexes in E. coli InfC TAP SPA TAP YacL RpoD SufD SufC SufB YacL RpoD SufD SufC SufB RpoB,C / in Various Regions of a Gene Hpr1 123456 Coding Regions Rna14 123456 3‘ Untranslated Tfg2 2345 Promoter Promoter 16 Spt16 123456 All Three All Three TFIIFTREX FACT CFIA Localization of Iwr1 on Drosophila Polytene Chromosomes Strategy: make peptide antibodies against Drosophila /


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

The Dosage Compensation Complex in Drosophila from Gilfillan et al., FEBS Lett. 567, 8 (2004) SXL in females prevents MSL2 translation MSL2 in males stabilizes roX, MSL1, and MSL3 DCC binds to high affinity sites on X chromosome DCC spreads to /) DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates by a Semiconservative Mechanism Grow cells in 15 N and transfer to 14 N/


Drosophila melanogaster Genetic studies Microsurgical manipulation One of the best understood developmental systems 13,600 genes Axis determination Signaling.

Drosophila melanogaster Genetic studies Microsurgical manipulation One of the best understood developmental systems 13,600 genes Axis determination Signaling pathway Transcriptional regulation/ canals 15 cells become nurse cells after germarium nurse cells left meiotic cycle, grow rapidly without division, and form polytene chromosomes A/P during oogenesis The oocyte move towards one end in contact with follicle cells Both the oocyte and the posterior follicle cells express high levels of the E-cadherin If E/


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

Dosage Compensation Complex in Drosophila from Gilfillan et al., FEBS Lett. 567, 8 (2004) SXL in females prevents MSL2 translation MSL2 in males stabilizes roX, MSL1, and MSL3 DMSL complex binds to high affinity sites on X chromosome DCC spreads to/ DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates by a Semiconservative Mechanism Grow cells in 15 N and transfer to 14 /


Mxc mutant alleles: Lethal (L1-L2) Pharate lethal viable Drosophila spermatogenesis mxc mutations affect germ cell development mxc mutations causes loss.

affect the DNA repair response following replicative stress multi sex combs (mxc) controls histone biosynthesis and replicative stress response in Drosophila Severine Landais and Leanne Jones, Salk Institute, San Diego, CA, USA. H1 10 mxc G46 ;Nanos-Gal4>/assembly is impaired In mxc mutants. (Described in White et al, JCB, Vol. 193 (4) 2011. Impaired histone mRNA levels in mxc mutants Decompaction of polytene chromosomes In mxc G43 salivary glands Germline specific H1 protein depletion in mxc mutants gonads /


Genetics: From Genes to Genomes

region Fig. 13.5 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Hartwell et al., 4th edition, Chapter 13 Polytene chromosomes in the salivary glands of Drosophila larvae In Drosophila, interphase chromosomes replicate 10 times without going through mitosis Each chromosome has 210 double helices Banding patterns are reproducible and provide detailed physical guide to gene mapping Total ~5000 bands, size of each band/


Welcome Each of You to My Molecular Biology Class.

molecules. The First Genome Maps Were Produced in Drosophila  Useful features of the flies in experimental research : Fecundity Rapid life cycle Four chromosomes (two large autosomes, a smaller X, and a very small fourth chromosome) Polytene chromosomes Drosophila melanogaster Endoreplication in the absence of mitosis generates enlarged chromosomes in some tissues of the fly Figure 21-17 Polytene chromosomes  Two major discoverise by the Morgan lab in 1910 : Mendel ’ s first law: Genes are/


Cell Biology & Molecular Biology

centromeres that aggregate to create a single large chromocenter Figure 4-38. The entire set of polytene chromosomes in one Drosophila salivary cell. These chromosomes have been spread out for viewing by squashing them against a microscope slide. Drosophila has four chromosomes, and there are four different chromosome pairs present. But each chromosome is tightly paired with its homolog (so that each pair appears as a single structure), which/


Chapter 08 *Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. *See separate FlexArt PowerPoint.

) These doublings produce a bundle of chromosomes that lie together in a parallel fashion This bundle is termed a polytene chromosome Polytene Chromosomes 8-55 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Figure 8.19 (a) Repeated chromosome replication produces polytene chromosome. (c) Relationship between a polytene chromosome and regular Drosophila chromosomes L R Chromocenter Each polytene arm is composed of hundreds of chromosomes aligned side by side. 4 32/


Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-1 Powerpoint to accompany Genetics: From Genes to Genomes Third.

gene. Fig. 14.5 14-10 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Polytene chromosomes in Drosophila salivary glands can be used to map deletions. Interphase chromosomes replicate 10 times. Interphase chromosomes replicate 10 times. Each chromosome consists of 210 (1024) double helices. Each chromosome consists of 210 (1024) double helices. Reproducible bands provide detailed physical guide to gene mapping. Reproducible bands provide/


Genetic Model Organisms worm mouse fish yeast fruit fly weed.

eyeless using the UAS-Gal4 system Specialized chromosomes Discovered by Balbiany in 1881 in salivary gland of drosophila larva (3 rd instars) Why salivary gland of drosophila larva will have Polytene Chromosomes???????????????? Polytene chromosomes Drosophila Polytene chromosome Drosophila Karyotype 1933, Painter showed the banding pattern in Drosophila 1935, Bridges Banding pattern is fixed in a particular chromosome in a particular species Polytene chromosome is found in 3 rd instar larva of Diptera Also/


CHAPTER 10 The Nature of the Gene and the Genome.

X-rays increases the rate of spontaneous mutations. Cells from the salivary gland of Drosophila have giant polytene chromosomes. Polytene chromosomes have been useful to observe specific bands correlated with individual genes. “Puffs” in polytene chromosomes allow visualization of gene expression. Polytene chromosomes 10.3 The Chemical Nature of the Gene (1) DNA is the genetic material in all organisms. The Structure of DNA: The nucleotide is the building block of/


Lab 8: Mitosis, Meiosis, and Chromosomes

Each anther contains 4 pollen sacs Look at cells in pollen sacs Pollen grains will be in different stages of meiosis Experiment 3: Polytene Chromosomes of Drosophila Today: Examine prepared slides of polytene chromosomes found in Drosophila melanogaster (fruit fly) Located specifically in: The gut. Malphigian tubules (excretory organs) of larvae. Footpads of adults. Salivary glands of larvae Polytene Chromosomes of Drosophila Giant chromosomes Have undergone many rounds of DNA duplication without cell/


Figure 6-16. Initiation of transcription of a eucaryotic gene by RNA polymerase II. To begin transcription, RNA polymerase requires a number of general.

of the assembling complex of general transcription factors, blocking further assembly. Some repressors also act at late stages in transcription initiation, for example, by preventing the release of the RNA polymerase from the general transcription factors. (/ al., Mol. Cell 3:297–307, 1999.)Figure 7-119 Figure 7-62. Localization of a Drosophila insulator-binding protein on polytene chromosomes. A polytene chromosome (see pp. 218–220) was stained with propidium iodide (red) to show its banding patterns—with/


1 The Big Picture: an outline of the concepts covered to date 1.Genes are physical units of hereditary that carry information from one generation to the.

used to map genes to specific regions of a chromosome. For example in Drosophila in some cells the chromosomes become highly replicated and exhibit very characteristic banding patterns: 14 In situ hybridization Polytene chromosomes Salivary glands Squash on slide Denature/Stain polytene chromosomes label gene probe Hybridize probe to polytene chromosomes Autoradiography 15 Drosophila X chr tip This map is actually very crude. The Drosophila genome consists of about 165 Mega base pairs (165/


Genetics: From Genes to Genomes

plan development in Drosophila: a comprehensive example Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Structure of the Drosophila Genome Chromosomes of Drosophila Four chromosomes designated 1-4 XY sex determination (XX females, XY males) Sex determined by X:A ratio Figure D.3 Fig. D.3 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Giant polytene chromosomes of larval/


Heterochromatineuchromatin (and facultative heterochromatin) Different types of chromatin Constitutive heterochromatin: constitute ~ 10% of nuclear DNA.

genes? bands inter-bands Drosophila polytene chromosomes Drosophila genome has 4 chromosomes polytene chromosomes result from endoreplication (DNA replication without cytokinesis)  giant chromosomes that are easily visible 2048 identical DNA strands X chromosome in Drosophila DAPI (DNA) Ac H4 X X the X chromosome of male Drosophila is transcriptionally twice as active increased transcription of the active X chromosome is marked by hyper-acetylated histones X chromosome inactivation In female mammals, one/


Chapter 21 Model Organism 2003 级生科 2 班 苏亮 200331060158.

in Drosophila  Morgan labs studied on Drosophila in 1910 led to two major discoveries: genes are located on chromosomes, and each gene is composed of two alleles that assort independently during meiosis; genes located on separate chromosomes segregate independently, whereas those linked on the same chromosome do not.  Hermann J. Muller provided the first evidence that environmental factors can cause chromosome rearrangements and genetic mutations.  Bridges used the polytene chromosomes/


This presentation was originally prepared by C. William Birky, Jr. Department of Ecology and Evolutionary Biology The University of Arizona It may be used.

guarantee accuracy and will not update the lectures, which were written when the course was given during the Spring 2007 semester. Section 16 Variation in Chromosome Nunber and Structure Indian Muntjac2N = 6/7 Chinese Muntjac2N = 46 Polytene Chromosomes Some insects, including Drosophila: During differentiation of some tissues (salivary glands, Malpighian tubules, etc.) cells go through repeated S phases (e.g. 10) without mitosis --> polyploid or/


Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr www.cengage.com/biology/starr Chapter 10 Controls Over Genes (Sections 10.1 - 10.5)

and histone proteins also affect transcription Molecules that methylate DNA prevent transcription Number of gene copies affects how fast its product is made Polytene chromosomes consists of hundreds or thousands of copies of the same DNA molecule Drosophila Polytene Chromosomes Giant polytene chromosomes form in Drosophila salivary gland cells by repeated DNA replication Transcription is visible (white arrows) where DNA has loosened mRNA Processing Before eukaryotic mRNAs leave the/


Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr www.cengage.com/biology/starr Chapter 10 Controls Over Genes (Sections 10.1 - 10.5)

and histone proteins also affect transcription Molecules that methylate DNA prevent transcription Number of gene copies affects how fast its product is made Polytene chromosomes consists of hundreds or thousands of copies of the same DNA molecule Drosophila Polytene Chromosomes Giant polytene chromosomes form in Drosophila salivary gland cells by repeated DNA replication Transcription is visible (white arrows) where DNA has loosened mRNA Processing Before eukaryotic mRNAs leave the/


10/22/2015fatchiyah, JB UB1 Fatchiyah, Ph.D. Lab. Molecular Biology Brawijaya University.

UB36 Phase-contrast image of Drosophila melanogaster polytene cromosomes. A. The end of the X-chromosome is marked with an arrow. Chromocentre is in the upper right corner. B. Shows a magnification of chromomere and interchromomere bands Polytene chromosome 10/22/2015fatchiyah, JB UB37 W-chromosome Yeast Artificial Chromosome 10/22/2015fatchiyah, JB UB38 Bacterial Artificial Chromosome Manipulation by Homologous Recombinant (HeintZ, 2001) Metaphase: Chromosome in middle cell Antibodies of a/


מבנה הקשר הפוספודיאסטרי 1) קשר 3 – 5 פוספו די-אסטרי 2) כיווניות

gland Dark bands and interbands Electron Microscope image of Drosophila polytene chromosome Folding and refolding at a time course of 22 hours Chromosome puffs Folding and refolding at a time course of 22 hours RNA synthesis in Chromosome puffs Red: newly synthesized BrUTP; Blue: old ones diffused RNA synthesis in Chromosome puffs RNA synthesis in Chromosome puffs Model of RNA synthesis in Chromosome puffs A model for the structure of an interphase/


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