Totipotency of Plant Cell

2535 Words Jun 28th, 2012 11 Pages
INTRODUCTION
Background
Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism, including extraembryonic tissues. Totipotent cells formed during sexual and asexual reproduction include spores and zygotes. Zygotes are the products of the fusion of two gametes. In some organisms, cells can dedifferentiate and regain totipotency. For example, a plant cutting or callus can be used to grow an entire plant. Human development begins when a sperm fertilizes an egg and creates a single totipotent cell called zygote. In the first hours after fertilization, this cell divides into identical totipotent cells. Approximately four days after fertilization and after several cycles of cell division,
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New leaves should appear on explants within 4 to 6 days and even new roots or flower buds within 7 - 10 days. These plants are ideal for basic botany and biology experiments as they grow quickly, maturing in about 40 days. Some genetically modified versions mature faster. This short growing time makes them easier to experiment with than most other plants.

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Figure 1 show the seedling of B. Rapa 2
2 http://www.flickr.com/photos/73288780@N00/71268710

MATERIALS
Seeds of rapid-cycling brassica (Brassica Rapa), agar, distilled water.
APPARATUS
Sterile forceps, damp sponge, beaker, cling film, sterile scissors, plastic tray.
PROCEDURE
Preparing the agar suspension 1. Molten agar was prepared by boiling 2.5 g of agar powder in 250 cm3 of distilled water. 2. The molten agar was poured into a beaker until about 2 cm in depth. This step should be done in the laminar flow and in aseptic manner to avoid contamination. 3. The agar was allowed to cool and solidify.

Figure 2: cool and solidify the culture solution to an agar Extracting the explants 1. Some seeds of rapid-cycling brassica (Brassica Rapa) was sprinkled on damp cotton placed in plastic tray and let to germinate.

Figure 3: Seed germinated on the damp cotton 2. When the seeds have germinated, the tops the seedlings (just below the shoot apex) was cut off using sterile scissors.

Figure 4: cut off the germinated
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