Chapter 12 - Mitosis Notes

Chapter 12 - Mitosis Notes - THE CELL CYCLE-Chapter 12...

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THE CELL CYCLE- Chapter 12  Ability to reproduce  = one  characteristic  of living  things Continuity of life based  on  the  reproduction  of cells •  Cell division functions in reproduction, growth, and repair        UNICELLULAR ORGANISMS use cell division for reproduction        MULTICELLULAR ORGANISMS use cell division to:            -repair/renew cells that die from normal wear and tear            -grow and develop from a single fertilized egg (zygote)            -reproduce asexually (EX: plants grow by cuttings) • Results in genetically identical daughter cells DNA molecules packaged into chromosomes  GENOME = cell’s  genetic  information Prokaryotes  genom e  - single  circular  loop  of DNA Eukaryotes  - several  DNA molecules  in multiple  chromo s o m e  bundles Every  eukaryotic  species  has  characteristic  number  of chromo s o m e s  in each  cell  nucleus       ~Human   SOMATIC  cells  (body  cells)  have  46  chromo s o m e s  (two  sets  of 23;  one  from  each  parent). ~Human   GAMETES  (sperm  or  eggs)  have  one  set  (23  chromo s o m e s );  ½  number  in somatic  cells Eukaryotic  chromo s o m e   - made  of  CHROMATIN  (DNA + associated  proteins)      PROTEINS  maintain  shape  and  control  gene  activity -  one  long,  linear  DNA made  up  of 100’s- 1000’s  of gene s         - spread  out as   CHROMATIN in NONDIVIDING  cells;            allows  acce s s  to info - condens e d  as   CHROMOSOMES in DIVIDING  cells;            allows  easier  transport       Duplicated chromosomes made up of:          -TWO IDENTICAL SISTER  CHROMATID  ARMS          -  TELOMERES -region  at ends  of arms;  prevent  degradation          - Region  where  chromatids  are  most  closely  attached  = CENTROMERE          -  KINETOCHORES -proteins  in centromer e  region  where  microtubules  attach     -            Once  chromatids  separate  in anaphas e  ~ considered  individual  chromo s o m e s TYPICAL HUMAN CELL might  divide  once  every  24  hours   M phase  < 1 hour       S  = 10- 12  hours        G 1  and G 2 = rest of time           G 1  most variable         G 0 - cell stops dividing MITOSIS  (in all body  cells) produce s   TWO  IDENTICAL daughter  nuclei  (clones) MEIOSIS  in gonads  (ovaries  or  testes)  produce s FOUR  NONIDENTICAL  daughter  cells  with  ½  the  number  of   chromo s o m e s                                                 as
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Chapter 12 - Mitosis Notes - THE CELL CYCLE-Chapter 12...

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