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  1. Reproduction How organisms produce offspring

  2. There are two kinds of Reproduction • Asexual reproduction • Sexual reproduction

  3. Asexual reproduction • The organism makes two or more offspring which are exact genetic copies of itself. • There are several methods of asexual reproduction:

  4. 1.Budding

  5. 2. Cuttings

  6. 3. Runners Strawberries

  7. 4. Cell Division Bacteria

  8. All living things come from other cells. To form a new cell, one cell must enlarge and divide into two new cells. This results in growth of The organism or replacement Of new tissue. MITOSIS

  9. Cell Division! How do organisms grow bigger?

  10. This regular sequence of growth and cell division is called the Cell Cycle. The 3 stages of the cell cycle are: • Interphase • Mitosis • Cytokinesis

  11. Interphase • Chromosomes are copied. This is called DNA replication. Each daughter cell must have a complete set of DNA to survive. 2. Chromosomes appear as threadlike coils (chromatin) at the start,but each chromosome and its copy (sister chromosome) change to sister chromatids

  12. Mitosis During mitosis, one complete copy of the DNA is distributed into each of the two daughter cells. There are 4 phases in mitosis

  13. Prophase • Mitosis begins • Centrioles (or poles) appear and begin to move to opposite ends of the cell • Spindle fibers form between the poles • The nuclear membrane breaks down

  14. Metaphase • The chromosomes line up across the center of the cell (meet in the middle) • the chromatids (or pairs of chromosomes) attach to the spindle fibers at the centromeres

  15. Anaphase • Chromatids separate and begin to move to opposite ends of the cell • The cell stretches out • Look for the “A”

  16. Telophase • Two new nuclei form • Chromosomes appear as chromatin (threads rather than rods) • Mitosis ends

  17. Cytokinesis • Cell membrane moves inward to create two daughter cells –each with its own nucleus with identical chromosomes.

  18. Remember this for mitosis:

  19. Make your own “Mnemonic” I P M A T C

  20. Animal Cells– • During cytokinesis, the cell membrane squeezes together around the middle of the cell. • The cytoplasm pinches into two cells. • Each get about half of the organelles.

  21. Plant Cells – • The rigid cell wall cannot squeeze together. • Instead, a cell plate forms across the middle of the cell and then a new cell wall forms

  22. Mitosis Review

  23. Biology is the only science in which multiplication means the samething as division- Unknown

  24. To Review

  25. Meiosis is thetype of cell division by which gametes (eggs and sperm) are produced. Makes gametes used in sexual reproduction. Meiosis:Sexual Reproduction

  26. Meiosis involves a reduction in the amount of genetic material. • The final cells have half the number of chromosomes. • When sperm and egg combine during • fertilization all required genetic information is in the fertilized egg.

  27. Interphase Before meiosis begins, genetic material is duplicated.

  28. First division of meiosis • Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids. • Metaphase 1: Chromosomes align at the equatorial plate. “meet in the middle”

  29. Anaphase 1: Pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the pair.

  30. Second division of meiosis: Gamete formation • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes align at the equatorial plate.

  31. Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained

  32. Haploid means that each cell has half the number of chromosomes.

  33. Meiosis I --- Meiosis II ---

  34. Meiotic Cell Division Reviewed -makes gametes used in sexual reproduction. 1. gametes (sperm and egg cells) formed during meiotic cell division have only ½ of the organism’s genetic information (23 chromosomes each)

  35. When sperm and egg combine during fertilization all required genetic information is in the fertilized egg. 2N


  37. Comparing Mitosis and Meiosis

  38. Asexual Reproduction Review • Cloning: • The same result as ASEXUAL • reproduction. • b. Cut a piece of stem from a plant • and it grows roots and develops a • new plant. • **this could be a clone of the plant

  39. Plant cloning

  40. c. Recently cloning animals that normally reproduce sexually has been done. “Dolly The Sheep”.

  41. What is it? A human ear!! The mouse lacks an immune system so the ear grows!

  42. Regeneration: asexual reproduction

  43. Sexual Reproduction Review: • Used to form sperm or an egg (gametes) • Will result in genetically different • offspring. • From two parent cells.

  44. Compare Mitosis and Meiosis