An antibiotic resistance gene in a vector usually helps in the selection of

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DNA cloning is the process of making multiple, identical copies of a particular piece of DNA. In a typical DNA cloning procedure, the gene or other DNA fragment of interest (perhaps a gene for a medically important human protein) is first inserted into a circular piece of DNA called a plasmid. The insertion is done using enzymes that “cut and paste” DNA, and it produces a molecule of recombinant DNA, or DNA assembled out of fragments from multiple sources. Diagram showing the construction of a recombinant DNA molecule. A circular piece of plasmid DNA has overhangs on its ends that match those of a gene fragment. The plasmid and gene fragment are joined together to produce a gene-containing plasmid. This gene-containing plasmid is an example of recombinant DNA, or a DNA molecule assembled from DNA from multiple sources. What is the point of making many copies of a DNA sequence in a plasmid? In some cases, we need lots of DNA copies to conduct experiments or build new plasmids. In other cases, the piece of DNA encodes a useful protein, and the bacteria are used as “factories” to make the protein. For instance, the human insulin gene is expressed in E. coli bacteria to make insulin used by diabetics. A restriction enzyme is a DNA-cutting enzyme that recognizes a specific target sequence and cuts DNA into two pieces at or near that site. Many restriction enzymes produce cut ends with short, single-stranded overhangs. If two molecules have matching overhangs, they can base-pair...

A. Transformed cells are the cells that have taken up the vector. B. Competent cells are the bacterial cells that are ready to take up the DNA. C. Recombinant cells are the cells whose DNA has been manipulated. Antibiotic resistance gene is a selectable marker gene which helps in the selection of transformed cells. With the help of marker, the cells carrying the vector (transformants) are easily distinguished from non transformants by selectively permitting the growth of transformants. Views: 5,812 REDHFERENT the cells derived from root apical and shoot-apical meristems and ambium differentiate and mature to perform specific functions. This act ading to maturation is termed as differentiation. During differentiation. pells undergo few to major structural changes both in their cell walls and potoplasm. For example, to form a tracheary element, the cells would pose their protoplasm. They also develop a very strong. elastic. gnoceliulosic secondary cell walls, to carry water to long distances even inder extreme tension. Try to correlate the various anatomical features ou encounter in plants to the functions they perform. Plants show another interesting phenomenon. The living differentiated (lls, that by now have lost the capacity to divide can regain the capacity fdivision under certain conditions. This phenomenon is termed as jadifferentiation. For example, formation of meristems - interfascicular ambium and cork cambium from fully differentiated parenchyma cells. Nhile doin...