Module 7

Module 7—Molecular Genetics: DNA, RNA, and Protein Synthesis

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Read

 

Genetic engineering is used in the laboratory to manipulate genetic material. Genes from plants, animals, and bacteria can be inserted into a different organism’s genetic material. Genetic engineering resulted in the goat producing silk in its milk. The gene for silk production from a spider was isolated and then inserted in the genetic material of the goat. This new combination of spider and goat DNA is called recombinant DNA. 

 

Researchers use restriction endonucleases, a specific group of restriction enzymes. Restriction endonucleases are able to “cut” the interior of DNA molecules within specific short sequences of nucleotides called target sequences. The actual site where the DNA is cut is called the restriction site. The target sequences and restriction sites are specific for different endonucleases.

 

“Figure 18.18” on page 648 shows the target sequence of GAATTC for a restriction endonuclease. Notice the restriction site within the target sequence. The small fragments of DNA created from this cleavage are called restriction fragments. If the same endonucleases are used to cut DNA from another organism, the restriction fragment’s sticky ends can base-pair with other organisms’ restriction fragments. DNA ligase can be used to splice these fragments together. Review the processes involved in genetic engineering by reading “Recombinant DNA” from page 647 to the end of page 648 in your textbook.

 

Watch and Listen

 

The animation “Restriction Endonucleases” describes restriction endonucleases, target sequences, sticky ends, and DNA ligase. It is an excellent illustration to support visual learning. Obtain a username and password from your teacher to gain access to the LearnAlberta website.

 

For more detail, watch “Genetic Engineering: The Science of Manipulating DNA.” Observe how students model the restriction endonuclease’s action using paper. Start at the beginning and stop viewing when you reach the section titled “Gel Electrophoresis.”

 

Self-Check

 

SC 1. To practise the concepts of genetic engineering, complete the Genetic Engineering Drag and Drop. Drag the correct label of the structure or description of the process to the numbered site where it belongs.

 

Read

 

Recreating the First Chimera

 

Read “Thought Lab 18.4: Recreating the First Chimera” on page 649 of your textbook and watch the animation, “Early Genetic Engineering Experiment,” which illustrates the process. Obtain a username and password from your teacher to gain access to the LearnAlberta website.

 

In “Thought Lab 18.4: Recreating the First Chimera,” you saw how scientists added foreign DNA (an amphibian gene) into the circular plasmid DNA of bacteria. Bacteria have been used in this way since 1982 to synthesize human insulin for the treatment of diabetes. Genetically engineered bacteria have also been used to produce other medicines such, as Human Growth Hormone to treat dwarfism and clotting factors to treat hemophilia.

 

Bioremediation involves using living cells to clean up the environment. For example, bacteria’s metabolic functions are genetically altered through genetic engineering to allow them to clean up soils polluted with PCBs, to clean up oil spills, to filter air from factory smoke stacks, and to remove heavy metals from water.

 

 

Genetic engineers have also been able to insert foreign DNA into plants and animals. Transgenic organisms are the result of these procedures. One example of a transgenic plant is golden rice, described in “Figure 18.22” on page 655 of your textbook. This figure shows the four different plant and fungus genes that have been added to the rice in order to increase the iron and vitamin A content of the rice. Read “Biotechnology Products” on page 654 up to “The Diagnosis and Treatment of Genetic Disorders” on page 658. Make summary notes for your course folder.

 

Self-Check

 

SC 2. To check your understanding, complete Plant Genetic Engineering. Check your answers as you go.

 

Module 7: Lesson 5 Assignment—Part 1

 

Retrieve the copy of the Module 7: Lesson 5 Assignment that you saved to your computer earlier in this lesson. Complete Part 1. Save your completed assignment in your course folder. You will receive instructions later in this lesson on when to submit your assignment to your teacher. 

 

Discuss

 

D 1. Some genetically modified plants have been surrounded by controversy. Bt corn is a genetically modified organism (GMO) that makes up about 50% of the corn crops grown in Canada. Bt is a naturally occurring soil bacterium called Bacillus thuringiensis. This bacterium produces a protein that acts as an insecticide. Scientists isolated this protein from Bt and inserted it into the corn DNA. The resulting transgenic Bt corn produces the Bt protein insecticide, thereby killing pests feeding on the plant.

 

In 1999, a study from Cornell University showed that monarch caterpillars who fed on milkweed covered in Bt corn pollen grew more slowly and had higher mortality rates. News agencies picked up this story quickly, and many articles and reports resulted. There was much controversy surrounding the results of this study.

 

Search the Internet for reports on Bt corn and monarch butterflies using search terms such as “genetically modified + Bt corn + genetically modified food + butterflies,” or search “archives + CBC + food” for the clip on genetically modified food. Collect reports that represent the two sides of the controversy. You may wish to start a table representing the opposing views in preparation for your lesson assignment.

 

Module 7: Lesson 5 Assignment—Part 2

 

Retrieve the copy of the Module 7: Lesson 5 Assignment that you saved to your computer earlier in this lesson. Complete Part 2. Save your completed assignment in your course folder. You will receive instructions later in this lesson about when to submit your assignment to your teacher.

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