Introduction to Genetic Analysis 92

Introduction to - Follow the stages of mitosis using the simplified ver-sion shown in Figure 3-24 1 Prophase The pairs of sister chromatids which

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91 3.3 Mitosis and meiosis Figure 3-23 Stages of the cell cycle. M = mitosis S = DNA synthesis G = gap Stages of the cell cycle Original cell Daughter cells G2 G1 M S stant down through the cell generations, and this is what mitosis achieves. The stages of the cell division cycle (Figure 3-23) are similar in most organisms. The two basic parts of the cycle are interphase (comprising gap 1, synthesis, and gap 2) and mitosis. An event essential for the propaga- tion of genotype takes place in the S phase (synthesis phase) because it is here that the actual replication of the DNA of each chromosome occurs. As a result of DNA replication, each chromosome becomes two side- by-side units called sister chromatids. The sister chro- matids stay attached through the action of specific ad- herence proteins.
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Unformatted text preview: Follow the stages of mitosis using the simplified ver-sion shown in Figure 3-24. 1. Prophase: The pairs of sister chromatids, which cannot be seen during interphase, become visible. The chromosomes contract into a shorter, thicker shape that is more easily moved around. 2. Metaphase: The sister chromatid pairs come to lie in the equatorial plane of the cell. Segregation Segregation Segregation Anaphase Telophase Anaphase I Telophase I Telophase II n Products of meiosis Prophase II Metaphase II Anaphase II Daughter cells 2 2 Figure 3-24 Simplified representation of mitosis and meiosis in diploid cells (2 n , diploid; n , haploid). (Detailed versions are shown in Figures 3-28 and 3-29.) 44200_03_p73-114 3/3/04 1:48 PM Page 91...
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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