Class Note for ECOL 320 at UA
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This 13 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Arizona taught by a professor in Fall. Since its upload, it has received 15 views.
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Date Created: 02/06/15
Asexual Reproduction in Eukaryotes Mitosis The Argentine bandT The real thing going on inside their cells mu m m mmquot sinus armm w wunmw a WWW m mm m luiapimu u mumm nw mm man Nuclear Genomes and Chromosomes Genome size in bp or kbp or Mbp or Gbp C value S cerevisiae Homo sagiens C 125 Mbp 33 Gbp Number genes 5770 20000 25000 or even 65000 Number of chromosomes in a haploid set N Diploids have 2N chromosomes Drosophila 4 Yeast 16 Humans 23 Dogs 39 Human chromosome size ranges 49 Mbp 246 Mbp z 16 82 cm Smallest is longer than entire cell Total z 1 In Go to httpWWWncbinlmnihgovmapvieWmap searchcgi Click on the number below any chromosome 22 might be best because it is smallest Chromosome Structure and Karyotypes III II Lxxxxx xxxxu r T T T T quotVT T Conventional diagram of metaphase teleme re gene eentrerner e gene ether gene telemere Basic chromosome structure chromosome with 2 chromatids T Centromere DNA sequence WHEEFCHOI E I where proteins bind to make a Chrer39netle kinetochore structure to which lchrematid microtubules bind v a39H eee Left human metaphase 1 2 3 E a a E E chromosomes squashed and it quot 1 tr e 19 l 4 5 g stained to show landmarks ii if is B g a a 3 Right diagram of human Si 4 iii 393 quot e 1 p 13 L karyotype with Gbands Short 13 14 15 15 1 18 p and long q arms 39339 quot3 l a a 19 2e 21 22 x I g g Z2J 33 J m Eukaryotic Cell Cycle Ce Cyce Mitosi s Cytokinesis cell division G2 G1 G1 S G2 interphase S Variable lengths Total time 15 m inutes gt days Animal cells in culture ca 1 day Q Q Diploid cell 2C 9 4C C amount of DNA 2N 9 4N Haploid cell C 9 2C N 9 2N chromosomes 9 chromatids Each eukaryotic chromosome replicates once and only once in each cell cycle Replication origins are caused to re in S phase then are prevented from re initiating Block to reinitiation is removed at mitosis Mitosis Diagrams 2 m if 9 i V I jigs qu r i xv7 anaphase zister kineiachures go to oppmsite teiuphaae poles nuclear membrane Separain chromatids now caHed farm chromosomes 2H chromosomes BEENA ten division Ezgtnkirieais In mitosis Sister kinetochores centromeres are attached to microtubules from opposite poles in metaphase therefore sister kinetochores and sister chromatids segregate at anaphase therefore daugher cells get one copy of each chromosome Many organisms are haploid during part or all of their life cycle egferns many unicellular protists fungi These include important experimental organisms Mitosis works the same way in haploid as in diploid cells except that there is only one set of chromosomes Eukaryotic Clones Clone all descendants of a single cell by mitosis Asexual reproduction Seen in 1 Unicellular organisms eg yeast Chlamydomonas progeny of single cell Handle like bacteria 2 Multicellular organisms eg animal plant a all cells in one individual b monozygotic twins etc c progeny produced by fission planaria or budding Hydra d progeny produced by vegetative propagation of plants aspen e progeny produced by some kinds of parthenogenesis some fish lizards Drosophila many plants Parthenogenesis egg develops into an adult Without fertilization Some forms of parthenogenesis produce diploid egg by mitotic division others do it by meiotic division followed by restoration of diploidy by various means All usually called asexual Some Asexual Eukaryotes Many eakaryotes are asexual in pm AMM39QVW 1 DWI Many parasites are asexual same A Sullivan wwwcellsaliveeom Today much genetic analysis is done With cells or organisms reproducing asexually Used for 0 Selecting mutants 0 Making custommade mutants by transformationtransfection 0 Growing identical organisms that can be used to separate effects of genotype from environment etc Modern genetic methods might allow one to use a clone for other purposes So far this one is impossible Verse by Isaac Asimov meant to be sung to tune of quotHome on the Rangequot quot0 give me a clone Of my own esh and bone With its Y chromosome changed to X And when it is grown Then my own little clone Will be of the opposite seX Clone clone of my own With its Y chromosome changed to X And when I39m alone ELIE W1th my own llttle clone We39ll both think of nothing but quot 4 b rim Hm L 3245 Summary 1 In the cell cycle each chromosome DNA molecule is replicated exactly once 2 In anaphase of mitosis sister centromeres kinetochores and hence sister chromatids segregate Thus each daughter cell gets one copy of each chromosome Consequence Daughter cells produced by mitosis have identical chromosomes Genes are identical barring mutation Cells and organisms produced by mitosis constitute a clone Today much genetic analysis is done With cells or organisms reproducing asexually Bacteria Yeast Chlamydomonas Animal including human and plant cells in culture Used to Select and identify mutants Custommade mutants Transformtransfect cells get them to take up a piece of a gene With a mutation built into it That piece of DNA replaces the resident gene Which is now mutant
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