Asexual Reproduction Webquest
INTRODUCTION:
What is asexual reproduction?
Asexual reproduction is a form of reproduction which requires only one parent. Unlike sexual reproduction, there is no exchange of genetic material or fertilization. Therefore, organisms that result from asexual reproduction will have the exact same DNA as their parent. Asexual reproduction is the simplest form of reproduction, since organisms are only making genetically identical copies of themselves. Asexual reproduction is also quite energy efficient, since organisms don’t need to spend the energy on finding a mate.
Asexual reproduction is seen as a natural method of reproduction among many different organisms in the world. It is a very common method of reproduction among less complex organisms and many higher organisms. Among the examples of asexual reproduction that we can see in the living world , there are many different methods of asexual reproduction. If we compare the reproduction of bacteria to the reproduction of yeast, for instance, we will be able to notice large differences.
Now you are ready to explore more about the topic.
PART A: Mitosis
Lets learn more about MITOSIS
A. visit the “Cells Alive” website.
When you are there, click on cell biology on the left side of the screen.
Then select Mitosis.
Watch the video and read over the description of the process of Mitosis.
You will be required to know the names of each step of the process.
When you have read and understood these directions click here to go to the “Cells Alive” site.
Go to the following webpage---->Cell Division
Click on the tab, “What does Mitosis Do?”
- What are the 2 major functions of mitosis? ________________________________________________
Click on the tab, “Built-in Controls in Mitosis”
- What are the 2 ways that cells “know” to stop dividing? ________________________________________________
Go to the following webpage--->Mitosis
- Label the steps of mitosis on your paper using the graphic.
NOW THAT YOU KNOW THIS, TRY PLAYING THE FOLLOWING GAME ABOUTH THE CELL CYCLE.
1. Click here------> http://nobelprize.org/educational_games/medicine/2001/
2. Click here------> http://www.purposegames.com/game/stages-of-mitosis-quiz
3. Click here------> http://www.quia.com/ba/83723.html
Read the sections on binary fission, budding, and regeneration.
PART B: Binary Fission
Binary fission:
In binary fission a single celled organism replicates its DNA and then divides itself into two separate cells. Each new cell will have the same DNA as the original cell. If the cell has organelles, half the organelles will be found in one of the daughter cells, and the other half will be found in the other daughter cell.
Binary fission is seen among prokaryotic cells such as bacteria. Bacteria do not have a nucleus, and their DNA only has one chromosome.Binary fission is a very efficient method of reproduction. E. coli, for instance, can divide as often as every 20 minutes. That means that when the living conditions are best for E. coli bacteria, they will grow and copy all of their DNA at an incredibly fast pace before undergoing binary fission to create two identical cells.
E.Coli Bacteria
Part C: Budding
Yeast
Yeast cells reproduce by a process called budding.
In this photo, some of the cells are budding. The cells in the top middle has already budded several times (notice the pock mark scars where buds have formed and separated.
Key Points:
parent organism divides into two unequal parts
buds break off and live independently
buds grow in size and can then have their own buds
the nuclei of both the parent and the daughter are identical
Hydras
Hydras are simple, hollow organisms which live in fresh water systems such as lakes, streams, and ponds or rivers. They are usually only a few millimeters long and are able to be easily seen with a microscope. Hydras have a tubular body that is topped with tentacles. They have a primitive nervous system, and move in a tumbling or cartwheel motion by continually bending their body over and gripping the surface that they are living on. They have a mouth area in the center of their tentacles, and a digestive region in the center of their tubular body. Hydras eat small aquatic insects by catching them with their tentacles and bringing them into their mouth.
Hydras reproduce asexually by the same method that yeast cells use to reproduce: budding. An adult hydra will begin the process of budding by producing a bulging region along their tubular body. This bulging region will grow and develop and form small tentacles at its tip. The small region will continue to grow and develop until it is large enough to support itself. Eventually the daughter hydra will break off from the mother hydra and will be free-living. The daughter hydra, being produced asexually, will be genetically identical to the mother hydra, but will begin its independent life smaller than its mother.
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| An adult hydra will produce a tiny bud on its tubular body. In time, this bud will grow to become a daughter hydra. |
Part D: Regeneration
Some organisms, such as sponges and sea stars, can regrow damaged or lost body parts. The process that uses cell division to regrow body parts is called regeneration. If a sea star breaks into piecesm a whole new organism can grow from each piece.
Research online the following organisms that can reproduce asexually. Identify how it reproduces (type of asexual reproduction).
- sponges
- starfish
- planarian
- echinoderms
If you have time:
Go back to the "Cells Alive" site and find the “puzzle” section.
Complete one of the jigsaw or crossword puzzles.