Cell reproduction
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Cell Reproduction. Mitosis & Meiosis. http://biotech-adventure.okstate.edu/low/basics/mitosis/mitosis-diagram/diagram.gif. Cell Cycle. http://www.bmb.psu.edu/courses/biotc489/notes/cycle.jpg. Mitosis. One type of cell division.

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Cell Reproduction

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Cell Reproduction

Mitosis & Meiosis


http://biotech-adventure.okstate.edu/low/basics/mitosis/mitosis-diagram/diagram.gif


Cell Cycle

http://www.bmb.psu.edu/courses/biotc489/notes/cycle.jpg


Mitosis

  • One type of cell division

Cell process in which the nucleus divides to form two nuclei identical to each other, and identical to the original nucleus, in a series of steps (prophase, metaphase, anaphase, and telophase)


Mitosis allows for growth and replaces worn out or damaged cells.


Interphase

  • Period of growth & development

  • Hereditary information (DNA) copied (replicated / duplicated)

  • Cells that do not divide (nerves) are always in interphase


http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/interphase/interphase.gif


Prophase

  • DNA begins to shorten & thicken

    • Now called chromatids / chromosomes

  • Centromeres form

  • Nuclear membrane breaks apart

  • Spindle fibers form


http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/prophase/prophase.gif


Metaphase

  • Chromatids / chromosomes line up

  • Centromere attaches to spindle fibers


http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/metaphase/metaphase.gif


Anaphase

  • Centromeres divide

  • Spindle fibers shorten

  • Chromatid pairs separate – move to ends of cell

  • Chromatids are now called

    • Each ½ of the pair is now called a chromosome


http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/anaphase/anaphase.gif


Telophase

  • Spindle fibers disappear

  • Chromosomes uncoil

  • Nuclear membrane forms

  • Cell divides (cytokinesis)


http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/telophase/telophase.gif


http://biology.nebrwesleyan.edu/benham/mitosis/


Mitosis Animation

http://www.johnkyrk.com/mitosis.html


Results of Mitosis

  • Division of nucleus

    • Nuclei are identical to each other

      • Same number & type of chromosomes


Asexual Reproduction

A type of reproduction - fission, budding, and regeneration - in which a new organism is produced from one parent and has DNA identical to the parent organism.


Asexual Reproduction

  • Offspring produced from one organism

  • Hereditary information is identical

  • Mitosis is one form of asexual reproduction


Sexual Reproduction

Meiosis


Sexual Reproduction

A type of reproduction in which two sex cells, usually an egg and a sperm, join to form a zygote, which will develop into a new organism with a unique identity.


Sexual reproduction results in a great variety, or diversity, of offspring.


Meiosis

  • The nucleus divides twice

    • Meiosis I

    • Meiosis II


http://biotech-adventure.okstate.edu/low/basics/meiosis/diagram/


Interphase

  • DNA is duplicated


Prophase I

  • DNA shorten & thicken

    • Forms chromatids / chromosomes


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase/leptotene/leptotene.gif


Metaphase I

  • Copied chromatids / chromosomes line up in middle of cell

  • Centromeres attach to spindle fibers


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-I/metaphase-I.gif


Anaphase I

  • Chromatid pairs are pulled apart

    • They DO NOT separate

  • Move to ends of cell


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-I/anaphase-i.gif


Telophase I

  • Cell divides

  • No further replication of hereditary material


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-I/telophase-I.gif


There are now two cells. Both cells have full sets of genetic material (chromosomes)


Prophase II

  • Similar to mitosis

    • Starts with TWO cells instead of one

      • Spindle fibers appear


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase-II/prophase-II.gif


Metaphase II

  • Duplicated chromatid / chromosomes line up in middle of cell

  • Spindle fibers attach to centromeres


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-II/metaphase-II.gif


Anaphase II

  • Centromere divides

    • Chromatids separate & move to ends of cell

      • Chromatids are now individual chromosomes


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-II/anaphase-II.gif


Telophase II

  • Spindle fibers disappear

  • Nuclear membranes form at each end of cell

  • Cells divide

    • Results in 4 cells

      • Each with ½ the original number of chromosomes


http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-II/telophase-II.gif


Meiosis Animation

http://www.johnkyrk.com/meiosis.html


In summary:Meiosis

  • Two cells form during meiosis I

  • In meiosis II, both of these cells form two cells

  • The two divisions of the nucleus result in four sex cells (gametes)

  • Each has one-half the number of chromosomes in its nucleus that was in the original nucleus


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