Asexual Reproduction:

It takes only one!

What is it and what’s it’s function?

• 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.

There are 5 types of Asexual Reproduction:

1. Binary Fission

2. Budding

3. Fragmentation

4. Spore Formation

5. Vegetative Reproduction

Binary Fission• 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 Protist: Paramecium Bacteria!

Budding

• 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

Fragmentation• Pieces from the parent break

off and form a new organism identical to the original parent

• Occurs in planaria (a free-living 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.

Spore Formation• 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.

Vegetative Propagation

• 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.

What are the benefits to reproducing asexually?

1. You don’t need a partner!2. You can reproduce faster in good conditions3. You use less energy4. You increase the population of your species5. 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?

What are the costs or disadvantages to reproducing

asexually?• 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

Matching: Which organism would use which type of asexual

reproduction?• ___ Yeast

• ___ Bacteria

• ___ Strawberries

• ___ Planaria

• ___ Hydra

• 1. Spore Formation

• 2. Vegetative Reproduction

• 3. Binary Fission

• 4. Budding

• 5. Fragmentation

Ans: Yeast – 1 & 4; Bacteria – 1 & 3; Strawberries – 2; Planaria – 5; Hydra – 4

Bibliography and Credits

• 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/fl

atworm.html• http://plantphys.info/Plants_Human/vegprop/vegpropn.html• http://www.microbe.org/microbes/spores.asp