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Chapter 11: The Continuity of Life: Cellular Reproduction At a Glance

Case Study: Cloning Conundrum

11.1 What Is the Role of Cellular Reproduction in the Lives of Individual Cells and Entire Organisms?

• The Prokaryotic Cell Cycle Consists of Growth and Binary Fission
• The Eukaryotic Cell Cycle Consists of Interphase and Cell Division
  During Interphase, the Eukaryotic Cell Grows in Size and Replicates Its DNA
  There Are Two Types of Cell Division in Eukaryotic Cells: Mitotic Cell Division and Meiotic Cell Division

11.2 How Is DNA in Eukaryotic Cells Organized into Chromosomes?

• The Eukaryotic Chromosome Consists of a Linear DNA Double Helix Bound to Proteins
• Eukaryotic Chromosomes Usually Occur in Homologous Pairs with Similar Genetic Information

11.3 How Do Cells Reproduce by Mitotic Cell Division?

Scientific Inquiry: Carbon Copies: Cloning in Nature and the Lab

• During Prophase, the Chromosomes Condense and the Spindle Microtubules Form and Attach to the Chromosomes
• During Metaphase, the Chromosomes Align Along the Equator of the Cell
• During Anaphase, Sister Chromatids Separate and Are Pulled to Opposite Poles of the Cell
• During Telophase, Nuclear Envelopes Form Around Both Groups of Chromosomes
• During Cytokinesis, the Cytoplasm Is Divided Between Two Daughter Cells

11.4 Why Do So Many Organisms Reproduce Sexually?

• Mutations in DNA Are the Ultimate Source of Genetic Variability
• Sexual Reproduction May Combine Different Parental Alleles in a Single Offspring

11.5 How Does Meiotic Cell Division Produce Haploid Cells?

• Meiosis Separates Homologous Chromosomes, Producing Haploid Daughter Nuclei
• Meiotic Cell Division Followed by Fusion of Gametes Keeps the Chromosome Number Constant from Generation to Generation
• Meiosis I Separates Homologous Chromosomes into Two Haploid Daughter Nuclei
  During Prophase I, Homologous Chromosomes Pair Up and Exchange DNA
  During Metaphase I, Paired Homologous Chromosomes Line Up at the Equator of the Cell
  During Anaphase I, Homologous Chromosomes Separate
  During Telophase I, Two Haploid Clusters of Duplicated Chromosomes Form
• Meiosis II Separates Sister Chromatids into Four Daughter Nuclei
• The Life Cycles of Most Organisms Include Both Meiosis and Mitosis

11.6 How Do Meiosis and Sexual Reproduction Produce Genetic Variability?

• Shuffling of Homologues Creates Novel Combinations of Chromosomes
• Crossing Over Creates Chromosomes with Novel Combinations of Genes
• Fusion of Gametes Adds Further Genetic Variability to the Offspring

Case Study Revisited: Cloning Conundrum

Links to Life: Cancer—Cell Division Run Amok