Cell Reproduction

1
Cell Reproduction

• Mitosis Meiosis

2
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/mitosis-diagram/diagram.gif
3
Cell Cycle
http//www.bmb.psu.edu/courses/biotc489/notes/cycl
e.jpg
4
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)
5
Mitosis allows for growth and replaces worn out
or damaged cells.
6
Interphase

• Period of growth development
• Hereditary information (DNA) copied (replicated /
  duplicated)
• Cells that do not divide (nerves) are always in
  interphase

7
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/phases/interphase/interphase.gif
8
Prophase

• DNA begins to shorten thicken
• Now called chromatids / chromosomes
• Centromeres form
• Nuclear membrane breaks apart
• Spindle fibers form

9
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/phases/prophase/prophase.gif
10
Metaphase

• Chromatids / chromosomes line up
• Centromere attaches to spindle fibers

11
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/phases/metaphase/metaphase.gif
12
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

13
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/phases/anaphase/anaphase.gif
14
Telophase

• Spindle fibers disappear
• Chromosomes uncoil
• Nuclear membrane forms
• Cell divides (cytokinesis)

15
http//biotech-adventure.okstate.edu/low/basics/mi
tosis/phases/telophase/telophase.gif
16
Interphase                                                              Prophase                                                             
Metaphase                                                              Anaphase                                                             
Telophase                                                              Interphase                                                             
http//biology.nebrwesleyan.edu/benham/mitosis/
17
Mitosis Animation
http//www.johnkyrk.com/mitosis.html
18
Results of Mitosis

• Division of nucleus
• Nuclei are identical to each other
• Same number type of chromosomes

19
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.

20
Asexual Reproduction

• Offspring produced from one organism
• Hereditary information is identical
• Mitosis is one form of asexual reproduction

21
Sexual Reproduction

• Meiosis

22
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.

23
Sexual reproduction results in a great variety,
or diversity, of offspring.
24
Meiosis

• The nucleus divides twice
• Meiosis I
• Meiosis II

25
http//biotech-adventure.okstate.edu/low/basics/me
iosis/diagram/
26
Interphase

• DNA is duplicated

27
Prophase I

• DNA shorten thicken
• Forms chromatids / chromosomes

28
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/prophase/leptotene/leptotene.gif
29
Metaphase I

• Copied chromatids / chromosomes line up in middle
  of cell
• Centromeres attach to spindle fibers

30
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/metaphase-I/metaphase-I.gif
31
Anaphase I

• Chromatid pairs are pulled apart
• They DO NOT separate
• Move to ends of cell

32
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/anaphase-I/anaphase-i.gif
33
Telophase I

• Cell divides
• No further replication of hereditary material

34
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/telophase-I/telophase-I.gif
35
There are now two cells. Both cells have full
sets of genetic material (chromosomes)
36
Prophase II

• Similar to mitosis
• Starts with TWO cells instead of one
• Spindle fibers appear

37
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/prophase-II/prophase-II.gif
38
Metaphase II

• Duplicated chromatid / chromosomes line up in
  middle of cell
• Spindle fibers attach to centromeres

39
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/metaphase-II/metaphase-II.gif
40
Anaphase II

• Centromere divides
• Chromatids separate move to ends of cell
• Chromatids are now individual chromosomes

41
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/anaphase-II/anaphase-II.gif
42
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

43
http//biotech-adventure.okstate.edu/low/basics/me
iosis/phases/telophase-II/telophase-II.gif
44
Meiosis Animation

• http//www.johnkyrk.com/meiosis.html

45
In summaryMeiosis

• 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