Asexual Reproduction
vs. Sexual Reproduction
While asexual reproduction only involves one organism, sexual
reproduction requires both a male and a female. Some plants and
unicellular organisms reproduce asexually. Most mammals and fish use
sexual reproduction. Some organisms like corals and komodo dragons can
reproduce either sexually or asexually. But in the long term (over several
generations), lack of sexual reproduction compromises their ability to adapt
to the environment because they do not benefit from the genetic variation
introduced by sexual reproduction.
Richard Rasmussen
Comparison chart
Asexual Reproduction
Number of One parent needed
organisms
involved
Cell division
Types
Advantages
Disadvantages
Two parents are required to
mate
Cells divide by Fission, budding , or
regeneration
Cells divide by Meiosis
Budding, vegetative reproduction,
fragmentation, spore formation
Syngamy and conjugation
Time Efficient; no need to search for
mate, requires less energy
Variation, Unique., organism
is more protected
No variation - if the parent has a
genetic disease, offspring does too.
Requires two organisms,
requires more energy
There is very little chance of
variation with asexual reproduction.
Evolution Mutations in DNA can still occur but
not nearly as frequently as in sexual
reproduction.
involvement of no formation or fusion of
sex cells gametes(sex cell)
unit of may be whole parent body or a bud
reproduction or a fragment or a single somatic cell
time period less
# of offspring two(minimum) or more than two
Richard Rasmussen
Sexual Reproduction
Sexual reproduction leads to
genetic variation in new
generations of offspring. This
is fundamental to evolution.
formation or fusion of
gametes(sex cell) occurs
gamete
more
One or more than one
Types
There are several different types of asexual reproduction. These include
budding, where the offspring grows out of the body of the parent, and
gemmules, (internal buds found in sponges) where the parent releases a
specialized mass of cells that will become a new individual.
There are two types of sexual reproduction. Syngamy is the permanent
fusion of two haploid gametes (Haploid describes a cell that contains a
single set of chromosomes. The term haploid can also refer to the number
of chromosomes in egg or sperm cells, which are also called gametes) to
create a zygote. In humans, this is called fertilization. Conjugation, on
the other hand, is a form of sexual reproduction in certain algae and fungi
where a male gamete unites with a female gamete resulting in the union of
their nuclei and the subsequent formation of a zygote.
Process
Asexual reproduction is reproduction that occurs without any interaction
between two different members of a species. Cells divide using mitosis, in
which each chromosome is copied before the nucleus divides, with each
new cell receiving identical genetic information.
Sexual reproduction is reproduction that requires a male and a female of
the same species to contribute genetic material. Special cells called gametes
are produced through meiosis, which halves the number of chromosomes
in each resulting cell. These cells are called haploid gametes. Fertilization
occurs when two gametes – one from a male and one from a female –
combine, producing a zygote with its own individual genetic makeup.
The following clip(18 mins 23 secs) explains meiosis and mitosis that
occurs in human reproduction. Please take notes.
Richard Rasmussen
Examples
Mitosis
Meiosis
(asexual reproductin)
(sexual reproductin)
Mitosis clip (7 mins 55 secs)
Meiosis clip (7 mins 40 secs)
Mitosis clip (20 mins 41 secs)
Meiosis clip (27 mins)
Richard Rasmussen
Advantages and Disadvantages
Asexual reproduction is well suited for organisms that remain in one
place and are unable to look for mates, in environments that are stable. It is
usually used by simple organisms such as bacteria. However, asexual
reproduction does not lead to variation between organisms, meaning that
entire groups can be wiped out by disease, or if the stable environment
changes.
Sexual reproduction allows for variation, the most fundamental
element of evolution. It therefore creates species that can adapt to new
environments and that cannot be wiped out by a single disease. However,
sexual reproduction requires significant energy on the part of the organism
to find a mate. It is not well suited to organisms that are isolated or stuck in
place.
Asexual reproduction is used by many plants, e.g. spider plants, bacteria,
hydra, yeast, and jellyfish. It is also involved in the creation of identical
twins, when one zygote splits into two identical copies.
Sexual reproduction is used by most mammals, fish, reptiles, birds and
insects.
Richard Rasmussen