CH10-Chromosomes,-Mitosis,-and-Meiosis-part-01 - CHAPTER...

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Unformatted text preview: CHAPTER 10: CHROMOSOMES, MITOSIS, and MEIOSIS When a cell divides iTs genes are replicaTed and copies are TransmiTTed To each daughTer cell (bl Growth and developmen '~.l ' ‘c: c ' ' d [ii-HUGO, l - r, "Fl-T'Dj’apl' {0 Tissue renew Ail-.4 Yl‘i'- l' ' u- 0 u. 3 £5.11 [2 1. Mechanisms involved in The Division of EukaryoTic Cells i) Karyokinesis — division of The nucleus (2 forms) °NiiTosis - nuclear division ThaT produces nuclei for somaTic cells (= body cells) -Nieiosis produces haploid nuclei for gameTes (e9 ovum and sperm) and spares (algae and planTs) ii) CyTokinesis— division of The cyToplasm To form 2 daughTer cells 2. FuncTions of Cell Division -ReproducTion — unicellular organisms reproduce asexually by cell division -6rowTh and DevelopmenT - repeaTed cell division of The ferTiIized egg produce a muITicellular aduIT -Tissue renewal (RegeneraTion) replacing cells ThaT die _ ammo—“x Cleavage — rapid divisions Human Ie ThaT converT zygoTe inTo _ _ mulTicellular blasTocysT GeneraTion To generaTion was 0 . \ sTages in developmenT aka.“ U _ Tack and sexual reproducTion - ' I: I s “9mg 2-Cel13lagg «cw, ,_ l n (3W9: i (am '\ 355% GameTes (sex cells) . .. Z T produced in gonads by meiosis wiTh _ I ygo e I half The DNA conTenT of body cells ferhl'zed °Vum w'll" I _ DNA from 2 cells c Gameiogeneais O i3 ’— —l m 3' % _"_ Ovary _ Yeslis E a .611 GasTrulaTion \Jf "- " blasTocysT forms 3 a n i El primary germ layers jg ‘ g Mafur-afion I a - H v _ (embrypnic Tissues) ' ‘ 3 body grows and sex organs Y - I (9,,“ g l' 5;? begin To produce gameTes . ' - fl yd“ I c? . _ n ___<_ .\ d ' Weeks 6} I by I or” \i. . / 5 (' i, ' . SomaTic cells (body cells) Organogenesis are clones of The zygoTe Organogenaelfi primary germ layers produced by miTosis give rise To organs ORGANIZATION of a EUKARVO'IIC CHROMOSOME (C'SOME) _- A Chromosome is a single DNA molecule complexed (= combined) with DNA binding proteins DNA is a |ong,thin, (-) charged molecule Histones are (+) charged proteins that package DNA molecules {a} A model for the structure ofa nucleosome. Each nucleosome bead contains a set of eight l‘llS'tOl'lG molecules, forming a protein core around which tho doublestranded DNA winds. The DNA surrounding the histories consrsts of 146 nucleotide pairs; another 100 nm r—‘—‘I (b) TEM of nucleosomes from the nucleus of a chicken cell. Normally] nucleosornes are packed more closely together, but the preparation procedure has spread them apart, revealing the DNA linkers. segment of DNA. about 60 nucleotide pairs long, links nucleosome beads. Figure 10.2 p 213 i—4oo nm —i Scaffolding proteins are nonhistone proteins that maintain c'some structure 300 nm fiber {looped damalns) 30 nm chromatin liner chromosome Condensed chromosome compact chromatin visible only in dividing cells DNA wound around a cluster 0| hislone molecules Scallolding protein Condensed chromalin I Exten dad chromatin Chromatin is a mixture of DNA and proteins Packed nucleosomes Figure 10.3 p 213 Histones are DNA. binding proteins 10 nm DNA is 2 "m [ Nucleosomes gene'flc '"fm'mam" Nucleosomes are “beads” of 8 histone (genes) DNA double helix proteins and the DNA wrapped around them KARYOTVPE — THE CHROMOSOMES of on INDIVUAL ORGANISM Each species has a characTerisTic number of c’somes in The nuclei of iTs cells (usually 4-50 per cell) 1) SomaTic cells are diploid body cells oTher Than ovum (= egg) and sperm in planTs and animals - Diploid (2n) is The condiTion of having 2 seTs of chromosomes per nucleus 2) Game‘les are haploid sex cells; eiTher an ovum or sperm in animals - Haploid (n) is The condiTion of having only 1 seT of chromosomes per nucleus Human male karyoType —46 chromosomes in The nuclei of body cells (23 homologous pairs) ° Similar in size, shape, and sTaining paTTerns - Carry The some genes aT The Homologous pair of c’somes E a E a if 3' one inheriTed from each parenT ' i g E a E é . i; It same loci ( = locaTions) it ' E 3 a i; f Q '3? £5 a; f k .4?! h ‘5 g E 3 Fl 1r i i z 5 i i é; .. 3 .n- n h l a s - ~. ’3 2 Fl - - a g 4 i a r E i In'l'erphase growTh period beTween divisions SEQUENCE of GROWTH and '61 - growTh and normal meTaboIism DIVISION in DIVIDING CELLS '5 - chromosomes are duplicaTed (= copied) Figure 10.4. P 214 '62 - final preparaTion for cell division One cell cycle: -InTerphase °M phase G1 {First gap phase) 8 (Synthesis phase) G2 (Second gap phase} ( Nondividing cellSexiT The cell cycle and enTer GU M phase is cell division miTosis and cyTokinesis ...
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