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GENERAL CONCEPTS 



A 



3 



D 



Figure 6.2. Meiosis in a hypothetical animal with a diploid chromosome number of 

 six. It has three pairs of chromosomes, of which one is short, one is long with a hook at 

 the end, and one is long and knobbed. A, Early prophase of the first meiotic division: 

 chromosomes begin to appear. B, Synapsis: the pairing of the homologous chromosomes. 

 C, Apparent doubling of the synapsed chromosomes to form groups of four identical 

 chromosomes, tetrads. D, Metaphase of the first meiotic division, with the tetrads lined 

 up at the equator of the spindle. E, Anaphase of the first meiotic division: the chromo- 

 somes migrating toward the poles. F, Telophase of the first meiotic division. G, Prophase 

 of the second meiotic division. H, Metaphase of the second meiotic division. /, Anaphase 

 of the second meiotic division. /, Mature gametes, each of which contains only one of 

 each kind of chromosome. (Villee: Biology.) 



