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reproduction by huangyuarong


   Reproduction from one organism.
   The cell division is mitosis.
   The genetic trats are same with the parent organism.
   Doesn’t effect evolution or variation.
   Seen in primitive organisms
   Only mutations can form variations
   Monoploid (n) or diploid(2n) organisms can be formed
   Reproduce rapidly
Mitosis is important in:
 Repair and regeneration.
 Growth
 Mitosis is a fundamental process for life. During mitosis,
  a cell duplicates all of its contents, including its
  chromosomes, and splits to form two identical daughter
As a result of the mitosis:
 2 new cells are formed
 New cells have same genetic material and chromosome
  number with mother cell.
 The genetic material and chromosome number of the
  new cells are same.
                           Interphase: Resting period of the cell.
                            Cell carries out normal activities.
                            Prophase: DNA of the cell replicates
                            itself. 2 sister chromatids are formed
                            Metaphase: Chromosomes with
                            sister chromatids stay in the middle of
                            the cell (equator).
                            Anaphase: Sister chromatids separate
                            from each other and go to the
                            opposite poles.
                           Telophase: Chromatids reach to the
                            poles and nuclear membrane is
Asexual reproduction types
1. Division(binary fission)
2. Budding
         Young organism is
         formed from the
         body of the existing
         Yeast cells, hydra
    3. Sporing ( fungi, algae, plasmodium,, fern, moss)
   Spores(n)       gametophyte plant(monoploid)        gametes
    fertilization      diploid plant (2n)   (meiosis)

                                                   Moss, ferns,
                                                   fungi and
                                                   Spores are
                                                   different from
                                                   gametes. They
                                                   are seen in
                                                   Forms new
                                                   individual by
4. Vegetative reproduction
                The parent plant grows
                runners and forms new
                plant. They are typically
                same. Strawberry, onion,
                violet, potato
          5. REGENERATION
    The parts which are cut off the plant or animal
    can form a new organism or an organ. Starfish,
    earthworm, lizard. But some animals can not
    produce new organism just form the organ or
    heal the wound.
   Reproduction from 2 parents. (one forms sperm, the other
    forms egg)
   Major Division is meiosis and the major process is fertilization.
   Newly formed organisms have new traits different from the
    parents and the other new organisms.
   Sexual reproduction enhance evolution and variation.
   These variations help organisms to survive better.
   Can be seen in higher organisms like animals and plants.
   The reasons for the genetic variations are: meiosis (crossing over,
    chromosomal lining in the metaphase) , fertilization and
   Newly formed organisms are diploid(2n)
   It is a long and slow process.
Meiosis is important in:
 formation of gametes (sperm, egg)
 reducing chromosome number
 genetic variation

As a result of the meiosis:
 4 new cells are formed
 New cells can have different genetic makeup from the
  mother cell
 New cells have half of the chromosome number of the
  mother cell.(n)
 The genetic makeup of the new cells can be different from
  each other.

   Prophase I:
    DNA replicates
    itself and forms a
    new DNA
    exchange genes
    (crossing over)

                                                    Prophase II: The chromosomes
Metaphase I: Homologous chromosomes                 become shorter and thicker.
(tetrad) line up in the middle of the cell(equator).Metaphase II: Spindle fibers attach to
Spindle fibers attach to the chromosomes.           the chromatids of the chromosomes.
Anaphase I: Homologous chromosomes                  Anaphase II: Sister chromatids of the
separate from eachother and go to the opposite chromosomes are separated and go to
poles.                                              the opposite poles of the cells.
Telophase I: Chromosomes reach to the               Telophase II: Totally 4 cells are formed.
opposite poles. Two cells are formed . he           Each cell can have a different genetic
chromosome number is reduced by meiosis I. make up and half of chromosome
          Mitosis and meiosis
           MITOSIS                           MEIOSIS

1. takes place in body cells.     1. takes place in germ cells
                                     and forms sex cells.
2. No crossing over (gene         2. crossing over can happen.
3. It has 1 cycle of the phases   3. It has 2 cycle of phases(2
   (1 division)                      division)
4. Produces 2 cells               4. Produces 4 cells

5. newly formed cells have        5. Newly formed cells have
   the same chromosome               the half of the
   number of the parent cell         chromosome number of the
                                     parent cell
6. The genetic make up of the     6. The genetic make up of the
   newly formed cells are            newly formed cells can be
   same with each other and          different from each other
   with the parent cell              and from the parent cell
         ISOGAMY                      HETEROGAMY

   2 Gametes of the same      2 gametes of different      2 gametes wqith 2
    morphological               morphological gametes        different structures
    structure unite.            unite. There is a            unite. The sizes of the
                                structural difference        gametes are very
   algae                       between sperm and egg        different from each
                                but not too much.            other. human
                               Algae, fungi
             This process is seen in bacteria,
             paramecium and green algae. 2
             individuals exchange genetic
             material with each other. Most of
             the time DNA is not exchanged ,
             instead plasmid which is a small
             part of DNA found in cytoplasm
             is exchanged.
             In that way organisms can gain
             new traits from the other
  It is the formation of a new organism from the unfertilized egg.

Male bee (n)                           Queen bee(2n)

           Mitosis                                   Meiosis

Sperm(n)                                          Egg(n)
                      Female bee(2n)
                                                       Male bee(n)
Queen bee(2n)               Worker bee(2n)
   Some organisms can carry both male and female
    reproductive system and organs. This process is
    called hermaphroditism. Earth worms, most of
    the plants are hermaphrodites.
   Some organisms can carry both male and female
    reproductive system and organs. This process is
    called hermaphroditism. Earth worms, most of
    the plants are hermaphrodites.
    Hermaphroditism causes variation but it is not as much as
    the variation in sexual reproduction.
    If same individual uses sperms and eggs from itself it will
    cause little variation.
    If gametes from 2 separate individuals fertilize they will
    cause more variation.
       n          In some organisms
                   sexual reproduction
                   follows asexual
                   reproduction. This is

                 Moss
                Plazmodium
               (asexual in human, sexual
2n         n      in mosquito)




n                              2n
   1. a female Anofele takes in gametes from the
    blood of human.
   2. gametes are fertilized inside the mosquito’s
    intestine. Zygote forms.
   3. Zygote forms spores by meiosis in mosquito.
   4. Mosquito bites human and infects him with
   5. Spores reproduce asexually in blood and liver
    of human. And spores form gametes .

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