Transcript 2.6 Asexual reproduction_McC

It takes only one!



Asexual Reproduction is: when 1 organism
gives rise to 2 identical organisms ( this is
essentially cloning!)
Organisms reproduce asexually when there is
an abundance of food, and when other
environmental conditions are very good
Asexual reproduction does not take a lot of
energy in terms of raising the offspring or
going through mating rituals; and allows
populations to grow quite large in a short
amount of time.
1.
2.
3.
4.
5.
Binary Fission
Budding
Fragmentation
Spore Formation
Vegetative
Reproduction


Protist: Paramecium
Bacteria!
Virtually the
same as mitosis,
binary fission
causes one cell to
divide into 2 after
all its organelles
and DNA have
replicated.
Binary fission
takes place in
single-celled
organisms such
as bacteria and
most protists



http://Hollenhorst and Catherine Fox

A miniature of the
original parent comes
off of the parent by an
out pouching of cells or
cytoplasm from the
parent
A new organism forms
eventually and breaks
away from the parent
Occurs in yeast, hydra
and some plants




Pieces from the parent break
off and form a new organism
identical to the original
parent
Occurs in planaria (a freeliving flatworm) and sea
stars.
Often fragments of these
seastars must include part of
the middle disc to create a
new organism.
Regeneration typical in sea
stars, demonstrates a similar
mechanism – in the photo
here only one arm is being
recreated.


When a bacterial cell senses
harmful or inhospitable
conditions, this vegetative
cell replicates its DNA and
its cell wall begins to
surround the new DNA
copy. A durable spore coat
forms around the developing
spore and eventually will
await better conditions for
growth.
Occurs in bacteria
(endospores), some protists,
fungi, ferns and mosses.


Stolons travel above ground
and land in another viable
place where soil is good
enough that another crown
and root system can be made
Occurs in strawberry plants,
spider plants, grasses, lilacs,
and ferns.
1.
2.
3.
4.
5.
You don’t need a partner!
You can reproduce faster in good conditions
You use less energy
You increase the population of your species
You can make an exact replica of yourself (for
those of you who are vain!) and thus know
exactly what the offspring will be.
* Farmers use seeds that are genetically identical when
they plant their crops….. How does this benefit
them?



There is no exchange of genetic information
and so no genetic variation will exist in the
population – evolution of a species may not
occur
Usually occurs only when environmental
conditions are good.
Organisms that have developed from asexual
reproduction are prone to diseases and viruses
or other environmental problems because of a
lack of variability in the genetic make-up of the
population

___ Yeast

1. Spore Formation

___ Bacteria


___ Strawberries

2. Vegetative
Reproduction
3. Binary Fission

___ Planaria

4. Budding

___ Hydra

5. Fragmentation
Ans: Yeast – 1 & 4; Bacteria – 1 & 3; Strawberries – 2; Planaria – 5; Hydra – 4






http://sciences.aum.edu/bi/BI2033/thomson/binaryfission.html
http://biology.about.com/library/weekly/aa090700a.htm
http://biology.about.com/gi/dynamic/offsite.htm?site
http://www.cs.tufts.edu/%7Ecabotsch/bulloughs/invertebrates/
worms/flatworm.html
http://plantphys.info/Plants_Human/vegprop/vegpropn.html
http://www.microbe.org/microbes/spores.asp