Ch09 - Chromosomes-Cell Cycle-Cell Division

Ch09 - Chromosomes-Cell Cycle-Cell Division - 9...

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9 Chromosomes, the Cell Cycle, and Cell Division
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9 Chromosomes, the Cell Cycle, and Cell Division 9.1 How Do Prokaryotic and Eukaryotic Cells Divide? 9.2 How Is Eukaryotic Cell Division Controlled? 9.3 What Happens during Mitosis? 9.4 What Is the Role of Cell Division in Sexual Life Cycles? 9.5 What Happens When a Cell Undergoes Meiosis? 9.6 How Do Cells Die?
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9.1 How Do Prokaryotic and Eukaryotic Cells Divide? Unicellular organisms use cell division primarily for reproduction. In multicellular organisms, cell division is also important in growth and repair of tissues.
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9.4 What Is the Role of Cell Division in Sexual Life Cycles? Asexual reproduction is based on mitotic division of the nucleus. It may be a unicellular organism reproducing itself, or: Cells of multicellular organisms that break off to form a new individual The offspring are clones —genetically identical to the parent. Sexual reproduction : the offspring are not identical to the parents. Meiosis produces gametes that differ genetically from the parents, and also from each other.
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9.4 What Is the Role of Cell Division in Sexual Life Cycles? Somatic cells —body cells not specialized for reproduction. Each somatic cell contains homologous pairs of chromosomes with corresponding genes. Each parent contributes one homolog . Gametes contain only one set of chromosomes Haploid : number of chromosomes = n Fertilization : two haploid gametes (female egg and male sperm) fuse to form a diploid zygote ; chromosome number = 2 n
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9.1 How Do Prokaryotic and Eukaryotic Cells Divide? Four events must occur for cell division: Reproductive Signal to initiate cell division Replication of DNA; duplication of cell components Segregation distribution of the DNA into 2 new cells Cytokinesis separation of the two new cells
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9.1 How Do Prokaryotic and Eukaryotic Cells Divide? In prokaryotes, binary fission results in 2 new cells. External factors such as nutrient concentration and environmental conditions are the reproductive signals that initiate cell division. Most prokaryotes have one chromosome, a single molecule of DNA; usually circular . Two important regions: ori —where replication starts ter —where replication ends
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9.1 How Do Prokaryotic and Eukaryotic Cells Divide? Replication occurs as the DNA is threaded through a “replication complex” of proteins in the center of the cell. Cytokinesis begins by a pinching in of the plasma membrane; protein fibers form a ring. As the membrane pinches in, new cell wall materials are synthesized, resulting in separation of the two cells.
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9.1 How Do Prokaryotic and Eukaryotic Cells Divide? Complex eukaryotes originate from a single cell, the fertilized egg. This cell results from the union of
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This note was uploaded on 04/09/2008 for the course BIO 140 taught by Professor Morvaridsoltani-bejnood during the Spring '08 term at University of Tennessee.

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Ch09 - Chromosomes-Cell Cycle-Cell Division - 9...

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