9: Chapter Chromosomes, the Cell Cycle, and Cell Division
Chromosomes, the Cell Cycle, and Cell Division
CHAPTER 9
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-07.jpg
Figure 9.7
30 nm fiber 300 nm loops 700 nm chromatid
Figure 9.7
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and Asexual
The cell cycle can repeat itself many times, forming a clone of genetically identical cells.
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and Asexual
Asexual reproduction produces an organism genetically identical to the parent. Any genetic variety is the result of mutations.
Hydra
www.marksimmons.org/closeup/ microimg/pages/hydra2.htm
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and Asexual
In sexual reproduction, two haploid gametes--one from each parent--unite in fertilization to form a genetically unique, diploid zygote. Review Figure 9.12
http://www.stanford.edu/dept/news/report/news/gifsarch2/Sperm_SEM_275.jpg
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
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Figure 9.12 Part 1
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
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Figure 9.12 Part 2
Figure 9.12 Part 2
http://www.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Plantae/Filicophyta/
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-12c.jpg
Figure 9.12 Part 3
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and Asexual
In sexually reproducing organisms, certain cells in the adult undergo meiosis, whereby a diploid cell produces haploid gametes. Each gamete contains a random mix of one of each pair of homologous chromosomes from the parent.
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Reproduction: Sexual and Asexual
The number, shapes, and sizes of the chromosomes constitute the karyotype of an organism.
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Mitosis Review
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear Divisions
Meiosis reduces the chromosome number from diploid to haploid and ensures that each haploid cell contains one member of each chromosome pair. It consists of two nuclear divisions. Review Figure 9.14
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear Divisions
During prophase I of the first meiotic division, homologous chromosomes pair, and material may be exchanged by crossing over between nonsister chromatids of two adjacent homologs. homologs. In metaphase I, the paired homologs gather at the equatorial plate. Each chromosome has kinetochore one and associates with polar microtubules for one pole. In anaphase I, entire chromosomes, each with two chromatids, migrate chromatids, to the poles. By the end of meiosis I, there are two nuclei, each with the haploid number of chromosomes with two sister chromatids. Review chromatids. Figures 9.14, 9.16 9.14,
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-14a.jpg
Figure 9.14 Part 1
Figure 9.14 Part 1
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear Divisions
In meiosis II, the sister chromatids separate. No DNA replication precedes this division, which in other aspects is similar to mitosis. The result of meiosis is four cells, each with a haploid chromosome content. Review Figures 9.14, 9.17
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-14b.jpg
Figure 9.14 Part 2
Figure 9.14 Part 2
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-16.jpg
Figure 9.16
Figure 9.16
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-17a.jpg
Figure 9.17 Part 1
Figure 9.17 Part 1
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
figure 09-17b.jpg
Figure 9.17 Part 2
Figure 9.17 Part 2
Chapter 9: Chromosomes, the Cell Cycle, and Cell Division
Meiosis: A Pair of Nuclear Divisions
Both crossing over during prophase I and the random selection of which homolog of a pair migrates to which pole during anaphase I ensure that the genetic composition of each haploid gamete is different from that of the parent and from that of the other gametes. The more chromosome pair...