Download Producing the Bovine Growth Hormone

WEB TUTORIAL 15.1
Producing the
Bovine Growth Hormone
Text Sections
Section 15.2 Transgenic Biotechnology, p. 234
Introduction
How do scientists use recombinant DNA technology to produce a protein such as
bovine growth hormone, which can then be used to increase milk production in
cows? In this tutorial, you’ll see how bacteria can be used as factories for the production of human or other animal proteins.
Learning Objectives
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Understand what a recombinant plasmid is.
Know the basic steps involved in producing recombinant proteins in bacteria.
Narration
Cloning Genes Using Bacteria
Each cell of a cow has all of the DNA needed to make all of the cow's proteins,
including bovine growth hormone, or BGH. This DNA is found in the chromosomes in each cell's nucleus. To clone the BGH gene, DNA is taken from the cow
cell's nucleus and cut with a restriction enzyme that leaves “sticky ends” on either
side of the BGH gene. “Sticky ends” are so-named because they are able to base
pair with any DNA molecule containing a complementary sticky end.
The BGH gene will be cloned by putting it into a bacterial plasmid. A plasmid is a
circular piece of bacterial DNA that normally exists separate from the bacterial
chromosome and can replicate itself. In order to insert the BGH gene into the plasmid, the plasmid must be removed from the bacterial cell and cut open with the
same restriction enzyme used on the cow DNA.
When the pieces of cow DNA and the cut plasmid DNA are mixed together, their
complementary sticky ends will join, forming recombinant plasmids. After the
recombinant plasmid has been formed it is put back into a bacterial cell, which
forms many copies, or clones, of the recombinant plasmid as it divides. Once
inside the bacteria, the BGH gene can be expressed, i.e., the bacterial cell uses the
information contained in the inserted BGH gene to produce BGH protein (called
recombinant BGH or rBGH). The rBGH is easily separated from the bacteria and
recovered from the media in which the bacteria are grown.
You should now be able to…
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Compare the experiments that Redi and Pasteur used to address the possibility of spontaneous generation and specify the experimental variables
being tested in their experiments.
Explain the importance of a control in an experiment.
Describe the effects of boiling on microbial growth.