Biology in the Laboratory


What is cloning?

A clone is a group of cells derived from the original cell by fission (one cell dividing into two cells) or by mitosis (cell nucleus division with each chromosome splitting into two). Cloning perpetuates an existing organism’s genetic makeup—in simpler terms, cloning produces genetically identical copies of a biological entity. Gardeners have been making clones of plants for centuries by taking cuttings of plants to make genetically identical copies. Such simple cloning starts with taking a cutting of a plant that best satisfies such criteria as reproductive success, beauty, or some other standard. Since all of the plant’s cells contain the genetic information that will allow the entire plant to be reconstructed, in most cases, the cutting can be taken from any part of the plant (although some plants do better with cuttings from a stem, others from leaves, and some even the time of the year the cutting is made). The cutting is then added to a culture medium having nutritious chemicals (such as a fertilized soil) and sometimes a growth hormone (not all plants need a root-growing hormone). The cells in the cutting eventually divide, doubling in size every six weeks until the mass of cells produces small white globular points called embryoids. These embryoids develop roots, or shoots, and begin to look like tiny plants. Transplanted into rich soils and compost, these plants grow into exact copies of the parent plant, with the process taking only a few months to over a year for the cloned plant to mature. This process is called tissue culture and has been used to make clones of asparagus, pineapples, strawberries, bananas, carnations, ferns, and others. Besides making highly productive copies of the best plant available, this method often controls viral diseases that are passed through normal seed generations.


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