Sexual and asexual modes of reproduction in animals and plants

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Reproduction (lec.01)


 Producing new individuals of same species
 Basic characteristic of life
 All organisms reproduce
 Different from all other aspects of life
 Not necessary for survival of individual
 For example if any organism cannot obtain food
 Or can't secure himself from predators may cause death!
 But why it is necessary???
 For survival of species
 produce new generations
 maintenance species & populations “individual eliminate”
 Continuity for Life
 Methods are variable for reproduction
 Asexual Reproduction
 Single parent new daughter cells / offspring produced by mitosis
 Same chromosome number
 Same characters
 Genetically identical offspring
 All genes same
 One parent
 Various methods
Binary fission ("division in half")
is a kind of asexual reproduction. It
is the most common form of
reproduction in prokaryotes such as
bacteria. It occurs in some single-
celled Eukaryotes like the Amoeba
and the Paramecium. In binary
fission DNA replication and
segregation occur simultaneously.




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,Sporulation is the formation of
nearly dormant forms of bacteria. In
a limited number of bacteria, spores
can preserve the genetic material of
the bacteria when conditions are
inhospitable and lethal for the normal
(vegetative) form of the bacteria.




Budding, a form of asexual
reproduction in which a new
individual develops from some
generative anatomical point of the
parent organism.




In vegetative propagation the
offspring of the plants are clones of
the original plant since no mixing of
DNA occurs. The most common
forms of vegetative propagation are
grafting, cutting, layering, tuber, bulb
formation, and tissue culture.


Parthenogenesis is a natural form of
asexual reproduction in which growth
and development of embryos occur
without fertilization. In animals,
parthenogenesis means development of
an embryo from an unfertilized egg cell.
In plants parthenogenesis is a
component process of apomixes.


Apomixis in flowering plants is defined
as the asexual formation of a seed from the
maternal tissues of the ovule, avoiding the
processes of meiosis and fertilization,
leading to embryo development. i.e
Vegetative Apomixis in Poa bulbosa;
bulbils form instead of flowers.

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,  Benefits Quick increase in number of individuals
All are genetically identical
 Commercial applications
 for valuable characteristics
 tissue culturing plants
 cloning of animals
 Disadvantages
 may harm population
 Rapid aging
 low resistance to environmental stress
 Moral & social acceptance especially Humans cloning???
 Sexual reproduction involves two parents
 Female (producing egg) Male (produces sperms)

Fertilization (egg + sperm)
 zygote grow complete individual
Gametes produced by meiosis haploid (n) chromosome in each
gamete ‘2n’ so mixing of genes 50/50 new combination union
restores (diploid 2n) so produces variation in species
changing and adaptation over Time so Evolution

Reproduction in plants (lec.02)
Asexual:
Layering Budding Cutting Grafting
Means of plant propagation in which It is a form of A plant cutting is a It is a technique that
a portion of an above-ground stem asexual piece of a plant that vegetatively joins
grows roots while still attached to the reproduction in is used in two plants into one. Instead of
parent plant and then detaches as an which a new horticulture for cross-pollinating
independent plant. Layering has individual vegetative two plants and producing a
evolved as a common means of develops from propagation. A piece hybrid seed, grafted plants use
vegetative propagation of numerous some generative of the stem or root of the roots and the bottom portion
species in natural environments. anatomical point the source plant is of one plant (rootstock) and
of the parent placed in a suitable attach it to a tender shoot from
organism. medium such as the top portion of another plant.
moist soil.




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