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A&P I Lab

A&P I Lab. Eukaryotic cells divide in one of two ways Mitosis Occurs in somatic (non-reproductive) cells Meiosis Occurs in germ (reproductive) cells Results in the production of gametes. Eukaryotes Have a Complex Cell Cycle .

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A&P I Lab

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  1. A&P I Lab

  2. Eukaryotic cells divide in one of two ways Mitosis Occurs in somatic (non-reproductive) cells Meiosis Occurs in germ (reproductive) cells Results in the production of gametes Eukaryotes Have aComplex Cell Cycle

  3. The complex cell cycle of eukaryotic cell is composed of several stages Interphase • G1 phase • Primary growth phase • S phase • DNA replication • G2 phase • Microtubule synthesis • M phase • Chromosomes pull apart • C phase • Cytoplasm divides Mitosis Cytokinesis

  4. How the cell cycle works

  5. Chromosomes • Humans have 46 chromosomes The 23 pairs of homologous chromosomes can be organized by size This display is termed a karyotype

  6. 7.3 Chromosomes • Chromosomes are composed of chromatin • Complex of DNA (~ 40%) and proteins (~ 60%) • A typical human chromosome contains about 140 million nucleotides in its DNA • This is equivalent to • About 5 cm in stretched length • 2,000 printed books of 1,000 pages each! • In the cell, however, the DNA is coiled

  7. Cell Division • The eukaryotic cell cycle consists of the following stages • Interphase • Mitosis • Division of the nucleus • Subdivided into • Prophase, metaphase, anaphase, telophase • Cytokinesis • Division of the cytoplasm

  8. Review the Concepts • What are collectively known as G1, S, and G2 phases of the cell cycle? • During which phase of the cell cycle is DNA synthesized? • How many chromosomes do humans have? 

  9. Interphase • Chromosomes replicate and begin to condense • Mitosis • Prophase • Nuclear envelope breaks down • Chromosomes condense further • Spindle apparatus is formed • Metaphase • Chromosomes align along the equatorial plane • Spindle fibers attach at the kinetochores • On opposite sides of the centromeres

  10. Fig. 7.7

  11. Anaphase • Sister chromatids separate • They are drawn to opposite poles by shortening of the microtubules attached to them • Telophase • Nuclear envelope reappears • Chromosomes decondense • Spindle apparatus is disassembled • Cytokinesis • Two diploid daughter cells form • Mitosis

  12. Fig. 7.7

  13. Animal cells • Cytokinesis • Cleavage furrowforms, pinching the cell in two Plant cells • Cell plateforms, dividing the cell in two

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