RECOMBINATION IN SEXUAL ORGANISMS 



71 



asexual process called mitosis. This process is quite different from 

 meiosis in that each daughter nucleus has the same number of chromo- 

 somes as did the parental cell. Figure 3.4 contains a diagram of mitosis 

 involving two homologous chromosomes in a diploid nucleus. In mitosis, 

 homologous chromosomes do not pair; they are duplicated individually, 

 the centromeres divide, and each pair of chromatids is arranged inde- 

 pendently on the metaphase plate. At anaphase, the chromatids sep- 



Centromere 



Diploid __ 

 nucleus 



Chromosome 



Prophase, 

 during which 

 chromosomes 

 condense by 

 coiling but 

 do not pair 



Anaphase, 

 sister 



chromatids l^^ 

 separate 



Interphase, 

 during which 

 chromosomes 

 duplicate 



Metaphase, 

 centromeres 

 divide 



Telophase, 

 formation of 

 new nuclei 



Cell division 

 completed, 

 nuclei in early 

 interphase 



FIGURE 3.4. A diagram of mitosis in a diploid cell with one pair on homologous 

 chromosomes. 



