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The Cellular Basis of Inheritance

The Cellular Basis of Inheritance. All cells come from cells. Figure 12.0 Mitosis. Why do cells divide?. Cells must divide to replace cells that die and to repair tissues. You are made of more than 200 trillion cells!. Cells are constantly dying.

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The Cellular Basis of Inheritance

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  1. The Cellular Basis of Inheritance All cells come from cells

  2. Figure 12.0 Mitosis

  3. Why do cells divide? • Cells must divide to replace cells that die and to repair tissues. • You are made of more than 200 trillion cells! Cells are constantly dying

  4. 2. Cells divide for growth and development Fertilized egg at first division

  5. What are the purposes of Cell Division? 3. Reproduction (ASEXUAL)

  6. Asexual Reproduction (budding) in a Hydra

  7. The Organization of DNA • DNA is organized into GENES • GENES are organized into CHROMOSOMES • What is a Chromosome? • Chromatin? • The Genome?

  8. Eukaryotic chomosomes

  9. What is a chromosome? A Chromosome has a centromere. It can be single or it can be duplicated.

  10. Chromosome duplication and distribution during mitosis Words to Know: Chromatids Centromere Chromosome

  11. S-phase The CELL CYCLE is the lifespan of a cell, and may include division. If the Cell cycle is 12 hours . . . S-phase- stands for DNA synthesis, lasts for 3 to 6 hrs G1 and G2 phase – stands for Gap phase G-phase

  12. Cytokinesis – process by which cytoplasm is divided into 2 Mitosis – Actual division of nucleus Diagram of cell cycle

  13. Figure 12.4 The cell cycle

  14. The Cell Cycle For most cells, 90% of the cell cycle is spent in Interphase. Suppose a cell is known to divide every 20 hours . . .

  15. Nuclear envelope is present Nucleoli are present Chromosomes are diffuse chromatin. Chromosomes replicate Cells spend most of the cell cycle in this stage INTERPHASE

  16. The Phases of Mitosis PROPHASE • The nucleoli disappear • Chromosomes condense • Mitotic Spindle begins to form • The nuclear envelope disappears

  17. Early prophase Late prophase

  18. The Phases of Mitosis METAPHASE • Chromosomes on metaphase plate (equator) • Sister chromatids attached to opposite poles by spindle fibers

  19. Metaphase

  20. The Phases of Mitosis ANAPHASE 1. Sister chromatids (now chromosomes) move toward the poles.

  21. Anaphase

  22. The Phases of Mitosis TELOPHASE • Nuclear envelope re-forms • Nucleolus re-forms • Chromosomes unwind • Daughter nuclei form • Cleavage furrow visible (cytokinesis)

  23. Telophase

  24. CYTOKINESIS • Animal Cells: Cleavage Furrow forms • Plant Cells: Cell Plate forms Cytokinesis Cell plate

  25. Figure 12.8 Cytokinesis in animal and plant cells

  26. Where would we look for cells dividing rapidly? Animals: Blastulas

  27. Interphase Prophase Metaphase Telophase Anaphase

  28. Figure 12.5x Mitosis

  29. Figure 12.5x Mitosis

  30. Where would we look for cells dividing rapidly? Plants: Meristems

  31. Figure 12.9 Mitosis in a plant cell

  32. Figure 12.9 Mitosis in a plant cell

  33. Figure 12-09x Mitosis in an onion root

  34. Amaryllis

  35. 9.4TUMORS AND CANCER TUMOR TYPES • Benign Tumors • Not cancer • Do not spread from point of origin • Usually easy to remove

  36. Malignant Tumors • May lose cellular ID and attachment need • Metastasis: This is when the cancer cells spread to other parts of the body

  37. Cancer Cells Lack Density- Dependent Inhibition Normal cells given nutrients, growth factors and substrate only form a layer one cell deep. Cancer cells lack this inhibition.

  38. Cancer: Caused by Mutations • Tumors are the result of mutations. • Mutated cells show several common errors: • Cells lack density-dependent inhibition • Cells lack anchorage dependence. • Cells become immortal • Growth factors can promote tumor growth

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