Lec13notescompletepart2

Lec13notescompletepart2 - Bio1A Lecture 13 Part 2 Chapter...

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Bio1A Lecture 13 Part 2 1 Chapter 20 DNA Technology and Genomics Understanding and Manipulating Genomes • Sequencing of the human genome was largely completed by 2003 • DNA sequencing has depended on advances in technology, starting with making recombinant DNA • In recombinant DNA, nucleotide sequences from two different sources, often two species, are combined in vitro into the same DNA molecule • Methods for making recombinant DNA are central to genetic engineering , the direct manipulation of genes for practical purposes • DNA technology has revolutionized biotechnology, the manipulation of organisms or their genetic components to make useful products • An example of DNA technology is the microarray , a measurement of gene expression of thousands of different genes DNA cloning permits production of multiple copies of a specific gene or other DNA segment • To work directly with specific genes, scientists prepare gene-sized pieces of DNA in identical copies, a process called gene cloning • Most methods for cloning pieces of DNA in the laboratory share general features, such as the use of bacteria and their plasmids • Cloned genes are useful for making copies of a particular gene and producing a gene product Fig. 20-2 Using Restriction Enzymes to Make Recombinant DNA • Bacterial restriction enzymes cut DNA molecules at DNA sequences called restriction sites • A restriction enzyme usually makes many cuts, yielding restriction fragments • The most useful restriction enzymes cut DNA in a staggered way, producing fragments with sticky ends ” that bond with complementary “sticky ends” of other fragments DNA ligase is an enzyme that seals the bonds between restriction fragments Fig. 20-3 Cloning a Eukaryotic Gene in a Bacterial Plasmid • In gene cloning, the original plasmid is called a cloning vector • A cloning vector is a DNA molecule that can carry foreign DNA into a cell and replicate there Producing Clones of Cells • Cloning a human gene in a bacterial plasmid can be divided into six steps: 1. Vector and gene-source DNA are isolated 2. DNA is inserted into the vector 3. Human DNA fragments are mixed with cut plasmids, and base-pairing takes place 4. Recombinant plasmids are mixed with bacteria 5. The bacteria are plated and incubated 6. Cell clones with the right gene are identified Fig. 20-4_1-3
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Bio1A Lecture 13 Part 2 2 Identifying Clones Carrying a Gene of Interest • A clone carrying the gene of interest can be identified with a nucleic acid probe having a sequence complementary to the gene • This process is called nucleic acid hybridization • An essential step in this process is denaturation of the cells’ DNA, separation of its two strands Fig. 20-5 Storing Cloned Genes in DNA Libraries • A genomic library that is made using bacteria is the collection of recombinant vector clones produced by cloning DNA fragments from an entire genome • A genomic library that is made using bacteriophages is stored as a collection of
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This note was uploaded on 09/16/2010 for the course BIO 1A taught by Professor Mccray during the Fall '09 term at Merritt College.

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Lec13notescompletepart2 - Bio1A Lecture 13 Part 2 Chapter...

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