Transcript Asexual Reproduction

Reproduction types
WHY DO CERTAIN ORGANISMS REPRODUCE THE WAY THEY DO?
Asexual reproduction
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Fission
Budding
Vegetative Propagation
Spore formation
Fragmentation
Parthenogenesis
Cutting
• Benefits of Asexual reproduction
– Quick
• Bacteria, for example can
reproduce very quickly.
• 1 bacteria can multiply to
thousands in days!
– Easy - No Need to spend lots of
resources finding a suitable mate.
Requires only one parent
– Produces identical offspring
So how do asexually reproducing
organisms ward of baddies?
– Well, generally they don’t
– Plague, competition, and changes in environment are devastating to these
creatures.
– Mutations in genetic code really are the only way these organisms survive
epidemics or changes in their surroundings.
Fission
– Fission is basically Mitosis
– Organism matures, grows,
synthesizes it’s own DNA, splits,
then repeats the process.
– Some examples of single cell
organisms that use fission for
Mitosis are
• Bacteria
• Algae
• Protozoa
Budding
– Budding is a type of asexual
reproduction that starts with a little
growth on the original organism
– The growth on the outside of the
original cell gets larger and larger,
until it can break off from the
original organism
– Once it’s free from the original
organism, it’s free to grow and get
larger and live its own life
– Examples
• Yeast
• Hydra
Lets look at a video of budding
Vegetative Propagation
– Many plants can
be cut from their
main plant body
and will sprout
roots
– Spider plants do
this well, place
the baby sprouts
in water, and
they’ll end up
growing roots, so
that you can
plant them
Spore formation
– Spores are formed as “gametes”
through mitosis asexually and
released.
– Likely catch in the wind and blow
through the air until meeting an
opposite “gamete”
These “gametes” fertilize each other and
form more multicellular organisms to
carry out the same process.
The following diagram shows the lifecycle of a
sporophyte (spore producing organism)
Fragmentation
– Think starfish
• Starfish can have one of its legs cut
off, and it will grow back.
• Not that uncommon, happens in our
livers too.
• What’s more uncommon is that the
leg that was cut off will grow into a
new starfish!
• Could be because some starfish
have developed special organs or
zones that can be broken off due to
damage or predators.
Parthenogenesis
– These girls go through
parthenogenesis, which literally
means “virgin birth” meaning, they
don’t need to mate to form an
embryo.
– We can say they’re girls, because
these reptiles, whiptail lizards, are
all girls.
– No males known to be in
existence.
– They make two female gametes
that can fertilize each other.
Cutting
Sexual reproduction
– There are surprisingly few organisms
that, in some time during their lives don’t
reproduce sexually.
– In fact about 99 percent of organisms on
earth reproduce sexually at least some
time during their lives.
– Leads to a great deal of diversity
– Diversity leads to a more sustainable
population that is better suited to ward off
competition and plague.
– Requires 2 parents
– Produces different offspring
– There are how many types of
asexual reproduction?
– Yeast performs what type of
sexual reproduction
– How do organisms who reproduce
asexually defend against plague
or competition?