Asexual reproduction is the production of new individuals from a single parent. This type of reproduction is generally observed in single-celled organisms. Here no fusion of gametes is involved and a single parent divides into two or more daughter cells. The offsprings produced are genetically and physically identical to the parent and are known as clones.
2. “ASEXUAL REPRODUCTION IS THE
MODE OF REPRODUCTION THAT
IS INVOLVED IN THE
PRODUCTION OF OFF SPRINGS
BY A SINGLE PARENT.”
3. WHAT IS ASEXUAL REPRODUCTION?
• Asexual reproduction is a mode of reproduction in
which a new offspring is produced by a single parent.
• The new individuals produced are genetically and
physically identical to each other, i.e., they are the
clones of their parent.
• Asexual reproduction is observed in both multicellular
and unicellular organisms.
4. • This process does not involve any kind of gamete fusion and
there won’t be any change in the number of chromosomes either.
• It will inherit the same genes as the parent, except for some
cases where there is a chance of rare mutation to occur
• Asexual reproduction is observed in both multicellular and
unicellular organisms.
• This process does not involve any kind of gamete fusion and
there won’t be any change in the number of chromosomes either.
• It will inherit the same genes as the parent, except for some
cases where there is a chance of rare mutation to occur.
5. CHARACTERISTICS OF ASEXUAL REPRODUCTION
1.Single parent involved.
2.No fertilization or gamete formation takes place.
3.This process of reproduction occurs in a very short
time.
4.The organisms multiply and grow rapidly.
5.The offspring is genetically similar.
7. BINARY FISSION
• The term “fission” means “to divide”.
• During binary fission, the parent cell divides into two
cells.
• The cell division patterns vary in different organisms,
i.e., some are directional while others are non-
directional.
• Amoeba and euglena exhibit binary fission.
8. • It is one of the simplest and uncomplicated methods
of asexual reproduction.
• The parent cell divides into two, each daughter cell
carrying a nucleus of its own that is genetically
identical to the parent.
• The cytoplasm also divides leading to two equal-
sized daughter cells. The process repeats itself and
the daughter cells grow and further divide.
9. • Step 1- Replication of DNA
• The bacterium uncoils and replicates its chromosome, essentially doubling its content.
• Step 2- Growth of a Cell
• After copying the chromosome, the bacterium starts to grow larger in preparation for
binary fissions. It is followed by an increase in cytoplasmic content. Another prominent
trait of this stage is that the two strands migrate to opposite poles of the cell.
• Step 3-Segregation of DNA
• The cell elongates with a septum forming at the middle. The two chromosomes are also
separated in this phase.
• Step 4- Splitting of Cells
• A new cell wall is formed at this phase, and the cell splits at the centre, dividing the
parent cell into two new daughter cells. Each of the daughter cells contains a copy of
the nuclear materials as necessary organelles.
10.
11. BUDDING
• Budding is the process of producing an individual
through the buds that develop on the parent body.
• Hydra is an organism that reproduces by budding.
• The bud derives nutrition and shelter from the parent
organism and detaches once it is fully grown.
12. BUDDING IN HYDRA
• Hydra is exclusively a freshwater organism having
different species.
• It is very small, just a half centimetre long.
• It is a cnidarian having a tubular body which is
composed of a head, distal end and afoot at the end.
13. • Budding in hydra involves a small bud which is
developed from its parent hydra through the
repeated mitotic division of its cells.
• The small bud then receives its nutrition from the
parent hydra and grows healthy.
• Growth starts by developing small tentacles and the
mouth.
• Finally, the small newly produced hydra gets
separated from its parent hydra and becomes an
independent organism.
14.
15. FRAGMENTATION
• Fragmentation is another mode of asexual
reproduction exhibited by organisms such as
spirogyra.
• The parent body divides into several fragments and
each fragment develops into a new organism.
16. FRAGMENTATION IN SPIROGYRA
• Vegetative reproduction is by fragmentation.
• Under the favourable conditions, vegetative reproduction is the
preferred mode of reproduction.
• The vegetative filament after fragmentation develops into a new
filament.
• Each fragment undergoes multiple division and elongation to
form a new filament
• Fragmentation can be due to mechanical injury or dissolution of
the middle lamella with a change in the salinity and temperature
of the water
17.
18. REGENERATION
• Regeneration is the power of growing a new organism from the
lost body part.
• For eg, when a lizard loses its tail, a new tail grows.
• This is because the specialized cells present in the organism can
differentiate and grow into a new individual.
•
• Organisms like hydra and planaria exhibit regeneration.
19. REGENERATION IN PLANARIA
• Planarian, has specialized stem cells called neoblasts.
• The neoblasts are crucial for the process of regeneration, where missing
tissues are regenerated after an injury.
• Furthermore, neoblasts are the only dividing cells of the adult animal. This is
comparable to pluripotent stem cells in humans
• However, these cells do not remain after birth. Hence, neoblasts in planarians
are the key to regeneration since these are the only type of cells that survive
into adulthood and are capable of division in the adult animal.
20.
21. SPORE FORMATION
• Spore formation is another means of asexual
reproduction.
• During unfavorable conditions, the organism develops
sac-like structures called sporangium that contain
spores.
• When the conditions are favorable, the sporangium
burst opens and spores are released that germinate to
give rise to new organisms
22.
23. ADVANTAGES OF ASEXUAL REPRODUCTION
• Mates not required.
• The process of reproduction is rapid.
• An enormous number of organisms can be produced
in very less time.
• Positive genetic influences pass on to successive
generations.
• It occurs in various environments.
24. DISADVANTAGES OF ASEXUAL REPRODUCTION
• Lack of diversity. Since the offsprings are genetically identical to
the parent they are more susceptible to the same diseases and
nutrient deficiencies as the parent. All the negative mutations
persist for generations.
• Since only one organism is involved, the diversity among the
organisms is limited.
• They are unable to adapt to the changing environment.
• A single change in the environment would eliminate the entire
species.
