Reproduction

1. Instructor Kanwal Nisa

2. Reproduction
• Reproduction is defined as a biological
process in which an organism gives rise to
young ones (offspring) similar to itself.
• The offspring grow, mature and in turn
produce new offspring. Thus, there is a cycle
of birth, growth and death.
• Reproduction enables the continuity of the
species, generation after generation.

3. Reproduction- Types
• All living organisms reproduce. Sexual
reproduction occurs when two
individuals are involved. Asexual
reproduction occurs when a single
individual is involved.

4. unicellular &
multicellular organisms
• In unicellular organisms, reproduction
occurs by the division of the entire cell.
The modes of reproduction in unicellular
organisms can be fission, budding, etc.
• whereas in multicellular organisms,
specialised reproductive organs are present.
Therefore, they can reproduce by complex
reproductive methods such as vegetative
propagation, spore formation, etc.
• In more complex multicellular organisms
such as human beings and plants, the mode
of reproduction is sexual reproduction.

5. Types of asexual
reproduction
• Fission
• Fragmentation
• Budding
• Regeneration
• Vegetative propagation
• Spore formation

6. Fission
It occurs in single-celled organisms,
belonging to the kingdom Protista and
Monera. It is further divided into two
types:
• 1. Binary fission
• 2. Multiple fission

7. Binary fission
• In binary fission, the single cell
divides into halves. A few
organisms that divide by binary
fission are bacteria and Amoeba.
In Amoeba, cell division or splitting
of cells can take place in any plane.
Binary fission can also occur in one
particular axis. For example,
Leishmania (a parasitic flagellated
protozoan), which causes kala azar
in humans, divides only
longitudinally.
Leishmania has whip-like flagella at
one end of the cell. Cell division
occurs in relation to these flagella.
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10. Multiple fission
• In multiple fission, a
single cell divides
into many daughter
cells simultaneously.
Examples:
• Plasmodium and
Amoeba

11. Fragmentation
• It is a form of asexual
reproduction in which an
entirely new organism is
formed from a fragment of the
parent.
It occurs in multicellular
organisms, whose body
organization is fairly simple
such as annelids, starfish,
fungi, lichens, and some algae
such as spirogyra.
The filaments of spirogyra,
upon maturation, break into
small pieces or fragments,
which grow into new individual.
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12. Regeneration
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Simple organisms such as Hydra and Planaria are capable of
producing new individuals through the process of regeneration
The process of regeneration involves the formation of new organisms
from its body parts. Simple organisms can utilize this method
of reproduction as their entire body is made of similar kind of cells in
which any part of their body can be formed by growth and
development.
• However, complex organisms have organ-system level of organization.
All the organ systems of their body work together as an
interconnected unit. They can regenerate their lost body parts such as
skin, muscles, blood, etc. However, they cannot give rise to new
individuals through regeneration.

13. Regeneration
• If the tail of a house lizard is cut, the missing part develops
again from the remaining part of the tail. In some cases,
regeneration is so advanced that an entire multicellular body is
reconstructed from a small fragment of tissue. Our body
spontaneously loses cells from the surface of the skin and
replaced by newly formed cells. This is due to regeneration.
Regeneration can be defined as the natural ability of living
organisms to replace worn out parts, repair or renew damaged
or lost parts of the body, or to reconstitute the whole body from
a small fragment during the post embryonic life of an organism.
Regeneration is thus also a developmental process that
involves growth, morphogenesis and differentiate
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15. Regeneration in lizard

16. Budding
• It is seen in certain fungi and
multicellular animals. In budding, the
parent cell or body gives out a lateral
outgrowth called the bud.
The nucleus divides and one of the
daughter nuclei passes into the
daughter cell. The bud grows in size
while being attached to the parent
body.
It then gets separated from the parent
by the formation of a wall. It then falls
off and germinates into a new
individual.
Thus budding results in the formation
of daughter cells of unequal sizes that
later grow to adult size. For example,
yeast, a fungus and Hydra, a
multicellular animal.
In case of Hydra, the daughter hydra
even develops mouth and tentacles
develop around the mouth before
being detached from the parent body.
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Budding in yeast
Budding in Hydra

17. Difference between regeneration
fragmentation
• Both regeneration and fragmentation are the type of asexual
reproduction. They both stands for the same meaning i.e
growth of an organism from a part of the body. Regeneration is
mainly associated with the animals whereas fragmentation is
mainly associated with the plants.
Regeneration is of two types, in the first type, a part of the body
that gets broken off or cut is regenerated. For example, lizards
cast off their tails to escape predators and then regenerate
them. The other type of regeneration involve the capacity to
give rise to an entire organism from a cut part. It is seen in
small invertebrates such as planaria and Hydra.
Fragmentation is also a mode of asexual reproduction. It is the
unintentional cutting up of the body of an organism which each
grows into different organism. It is most commonly seen in
some algae.
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18. Spore formation in Rhizopus
• The thread-like structures that
developed on the bread in are the
hyphae of the bread mould
(Rhizopus).
• On the other hand, the tiny blob-
on-a-stick structures are involved
in reproduction. The blobs are
sporangia, which contain cells,
or spores, that can develop into
new Rhizopus individuals
• The spores are covered by thick
walls that protect them until they
come into contact with another
moist surface and can begin to
grow.

19. Vegetative reproduction
• There are many plants in which
parts like the root, stem and leaves
develop into new plants under
appropriate conditions

20. Advantages of Vegetative
reproduction
• Such methods also make possible the propagation of
plants such as banana, orange,rose and jasmine that
have lost the capacity to produce seeds.
•
Plants raised by vegetative propagation can bear
flowers and fruits earlier than those produced from
seeds.
•
• Another advantage of vegetative propagation is
that all plants produced are genetically similar to the
parent plant.

21. Vegetative reproduction by
leaf
• Similarly buds
produced in the
notches along
the leaf margin
of Bryophyllum
fall on the soil
and develop
into new plants

22. Vegetative reproductionby stem
1. Runners are
stems that grow
horizontally
above the
ground. They
have nodes
where buds are
formed. These
buds grow into
a new plant.

23. Vegetative reproductionby roots
• New plants will
grow out of swollen,
modified roots
called tubers. Buds
develop at the base
of the stem and
then grow into new
plants

24. Stem cutting
• Cuttings: Cuttings are
part of the plant that is
cut off of the parent
plant. Shoots with
leaves attached are
usually used. New
roots and leaves will
grow from the cutting.
The shoot is cut at an
angle.

25. Layering
• In layering a
shoot of a parent
plant is bent until
it can be covered
by soil. The tip of
the shoot remains
above ground.
New roots and
eventually a new
plant will grow.
These plants can
then be
separated.

26. Grafting
• In grafting 2 plants are
used to develop a new
plant with combined
traits from the 2 parent
plants. In grafting the
scion is the above
ground part of one
plant. The scion is
attached to the stock
which is the rooted
part of the second

27. WHAT IS ASEXUAL
REPRODUCTION
 It is one of the two types of reproduction which splits an
organism into two to produce another of the same species.
 In asexual reproduction, one organism produces offspring
that are identical to itself and inherits the genes of that
parent only.
 It is reproduction which does not involve ploidy reduction,
fertilization, gametes or sex cells.

28. FOUR TYPES OF ASEXUAL
REPRODUCTION IN ANIMALS
• 1) Fission or Budding
• One or more individuals are formed from the
original.
• The new organism remains attached as it grows,
separating from the parent organism only when it is
mature.

29. 2) Fragmentation
• A parent breaks into different fragments that
eventually form new individuals.
• The splitting may or may not be "intentional"- it may
occur due to man made or natural damage by the
environment or predators this kind of organism´s
may develop specific organs or zones that may be
shed or easily broken off.

30. Regeneration
• When an animal that is capable of regeneration loses
a body part, it can grow a replacement part. If the
lost body part contains enough genetic information
from the parent, it can regenerate into an entirely
new organism.
• Echinoderms exhibit this type of reproduction
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31. 4) Gemmules (internal budding)
• A parent releases a specialized mass of cells that
can develop into an offspring.
• Gemmules are internal buds found in sponges that
are the result of asexual reproduction, and are a
response to a hostile environment.
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