Cell Reproduction
description
Transcript of Cell Reproduction
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
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
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