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The Nucleus Asexual Reproduction: Mitosis & Cell Division

The Nucleus Asexual Reproduction: Mitosis & Cell Division. General Info:. Nucleus: the “brain” of the cell controls the cells activities responsible for cell division, protein synthesis. General Info Cont. Nucleus: contains genetic material called DNA

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The Nucleus Asexual Reproduction: Mitosis & Cell Division

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  1. The NucleusAsexual Reproduction: Mitosis & Cell Division

  2. General Info: Nucleus: • the “brain” of the cell • controls the cells activities • responsible for cell division, protein synthesis

  3. General Info Cont. Nucleus: • contains genetic material called DNA • DNA long chain (chromatin) of genetic information (eukaryotes) • In prokaryotes (bacteria) DNA is in the shape of a ring called a plasmid

  4. Nucleus Nucleolus Chromatin

  5. Chromosomes: • made of Deoxyribonucleic Acid  DNA wrapped around proteins • Chromosomes in eukaryotes are “rod shaped” structures made of DNA and proteins

  6. Chromosomes: • consist of 2 halves called chromatids • “sister chromatids” are connected in the center by a centromere

  7. Chromosome (Coiled chromatin)

  8. Ck question Topic: DNA and Chromosomes Date: 1-4-2010 • Genetic material of a cell is called … • The location of #1 • The ring of DNA found in Bacteria is… • Chromosomes consist of 2 halves known as…

  9. Chromosome Numbers: • Each species has a characteristic number of chromosomes in each cell. • ex. Fruit flies (drosophila) = 8 chromosomes • horse has 64 chromosomes • humans have 46 and chimpanzees have 48 chromosomes

  10. From 7 characteristics of living things: All living things  Grow • Growth occurs from the division of cells. • Cell Division (cellular reproduction) allows cells to: • Grow in size • Grow in number • Replace worn out, injured or dying cells

  11. 2 Forms of Cellular Reproduction (cell division): • Asexual Reproduction  involves only one parent cell • Occurs in Autosomes or somatic cells … body cells • Plants/animals

  12. 2 Forms of Cellular Reproduction (cell division) Cont… c. protists (protozoan) = single celled organisms (binary fission) d. fungi e. bacteria = binary fission

  13. 2 Forms of Cellular Reproduction (cell division): • Sexual Reproduction involves 2 parents cells • Gametes = sex cells • Making gametes!!!

  14. Sexual reproduction: Occurs in sperm cells and egg cells

  15. The Cell CycleAsexual Reproduction aka MITOSIS The Cell Cycle is responsible for: • birth and death of a cell • Cell division of nucleus, home of hereditary information…chromosomes • Cell division (Cell Cycle) consists in 3 processes

  16. Cell Cycle consists in 3 processes • Interphase • Division of the nucleus=mitosis 3. Division of the cytoplasm = cytokinesis

  17. Ck question Topic: Cell reproduction Date: 1-4-2010 • How many chromosomes does a normal humans have? • Identify 3 reasons cells divide. • The 2 types of cellular reproduction are… • Define gametes. • Define autosome.

  18. Before a cell divides…. Interphase (nucleus) • Cell spends most time here

  19. Interphase: • Divided into 3 phases • G1 – cells grow to mature size • S – DNA is copied or duplicated called DNA replication • G2 – cell prepares to divide • Some cells have a G0 phase, they do not replicate after maturity. Ex. Nervous System

  20. Mitosis: One cell (PARENT CELL) divides into 2 identical cells (Daughters) • divisions: nucleus divides • a series of chronological steps: • prophase • metaphase • anaphase • telophase Division of the nucleus (DNA)!!

  21. Mitosis

  22. Prophase: • Chromatin condenses, becomes visible strands of DNA called chromosomes • 2 chromosomes are made of “sister chromatids” • chromatids are connected by centromere • centrioles in animal cells begin to separate (opposite ends or poles)

  23. Prophase Cont. • spindle fibers form (football shape) from the centrioles and connect to centromere of each chromatid • nuclear membrane fades • chromatids (chromosomes) begin moving to center

  24. Spindle fibers Centrioles Centromere Chromosomes

  25. Metaphase: (middle) • chromosomes (chromatids) line up in the middle of the cell • centromere divide • chromosomes are pulled apart separate chromosomes (???)

  26. Spindle fibers Chromosome Centromere

  27. Anaphase: (away) • centromere divides • chromatids separate • move to opposite ends of cell • complete set of chromatids go to each pole

  28. chromatid

  29. Telophase: • final step of mitosis • chromatids unwind, spindle fibers disappear • nuclear membrane forms around each of chromatids

  30. Cytokinesis: • final step in the cell cycle • cytoplasm (and organelles) divide equally in cells • animals-pinching in of the cell membrane forming a cleavage furrow • plants - cell plate forms across the middle growing outward

  31. In animal cells • (begins outside the cell)

  32. In plate cells • (begins inside the cell)

  33. Results of Mitosis: • division of the nucleus (Asex. Reprod.) • products are 2 new cells with identical information to each other and to the parent cell • most cells reproduce asexually  mitosis • ex. Of cells produced through mitosis include: in animals: blood cells, skin cells, cheek cells, in plants: root cells, stem cells, leaves

  34. Parent Cell Identical Daughter Cells

  35. Identical Daughter Cells Two identical daughter cells Parent Cell

  36. mitosis

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