Notes: Sexual and
Asexual Reproduction
Sexual Reproduction – process in
which 2 parents contribute genes (via
sperm and egg) to form a new
individual
The resulting individual will be
a combination of the male and
female parents. This
combination of genes creates
an entirely unique individual
unlike any other.
Sexual Reproduction –
Requires two sex cells – egg and sperm
The egg and sperm join to form an entirely new
organism (called a zygote)
Different from the parent organism
Offspring has half of the Mother’s DNA and half of
the Father’s DNA
Benefits of Sexual Reproduction
• Genetic differences help a species survive
adverse conditions like disease and
environmental changes. If individuals have
variation, some of them may have a gene that
helps them survive when others do not.
Downsides of Sexual Reproduction
• Sexual Reproduction requires two individuals: It
takes valuable time and energy to find or compete
for a mate
• Sexual reproduction takes a while – depending on
the size of the organism it can take a long period of
time for the offspring to grow enough to be born.
Ex: for humans it takes 266 days to reach full term
and elephants take 624 days. (This is called a
gestation period)
Downsides of Sexual Reproduction
• Offspring of sexually reproducing organisms usually
require time for care from the parents after birth as
well. There is time needed between litters.
• Organisms that reproduce sexually usually have
offspring that develop inside the mother. This limits
the amount of offspring one can have at a time.
Asexual Reproduction – reproduction
involving only one parent organism.
The offspring created
through asexual
reproduction have the
exact same genetic
material as the
parent; the offspring
is a CLONE of its
parent.
Benefits of Asexual Reproduction
• There is no energy or time required to find a
mate.
• The production of offspring is usually external so
the parent can have LOTS of offspring in a very
short amount of time.
• There is no parental care required; since the
offspring are copies of the parent there is no
“baby” stage
Downsides of Asexual Reproduction
• Offspring of asexually reproducing organisms are
identical to their parents. All members of the
species are identical to one another. If a disease or
change in environment occurs, all individuals will be
affected.
Types of Asexual Reproduction:
Binary fission - one single cell copies itself
and splits in two, creating a new
individual.
**This is how
BACTERIA
reproduce**
Binary Fission in Bacteria
Types of Asexual Reproduction:
Budding- an offspring grows out of the
body of the parent and then breaks off.
**The offspring organism is smaller than the parent.
The buds grow into fully matured individuals which
eventually break away from the parent organism.**
Hydra is an Animal that
Reproduces through
Budding
Types of Asexual Reproduction:
Vegetative Reproduction- process by which
new plant "individuals" arise or are obtained
without production of seeds or spores
***Examples are the runners of strawberries, the tubers of
potatoes, and the bulbs of onions***.
Types of Asexual Reproduction:
Regeneration- if a piece of a parent is
detached, it can grow and develop into a
completely new individual.
**This is how
STARFISH
reproduce**