1. Module 7

1.20. Page 4

Lesson 5

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

Lesson Summary

 

This lesson addressed the following focusing questions:

  • What roles do restriction enzymes and ligases play in changing the genome?
  • What are some technologies involved in genetic engineering?
  • What are the implications of genetic manipulation?

This lesson has discussed the processes and controversy involved in genetic engineering. You have learned about the steps needed for recombinant DNA, including how DNA ligase is used to join the sticky ends created at the restriction site by restriction endonucleases. You have learned about different transgenic organisms and chimeras, and you have discussed the advantages and disadvantages of these genetically altered organisms.

 

You have learned about the mechanisms involved in cloning and gene therapy, and you have also discussed the controversy surrounding this science. Who owns DNA was one of the final topics of discussion in this unit. Many difficult social and ethical issues were raised in this lesson, and it will be very exciting and interesting to see what the future holds for genetic engineering. In the next lesson you will see how the entire human DNA sequence was identified and how a knowledge of DNA sequences can help trace ancestral relationships.

 

Lesson Glossary

 

Consult the glossary in the textbook for other definitions that you may need to complete your work.

 

bioremediation: use of living cells to perform environmental clean-up tasks, such as using bacteria to degrade PCBs into harmless compounds

 

chimera: a genetically engineered organism that contains DNA from unrelated species

 

DNA ligase: an enzyme that splices together Okazaki fragments on the lagging strand or sticky ends that have been cut by a restriction endonuclease during DNA replication

 

gene replacement therapy: the process of changing the function of genes to treat or prevent genetic disorders

 

genetic engineering: manipulation of genetic material to alter genes and blend plant, animal, and bacterial DNA

 

germ-line therapy: gene therapy used to modify the genetic information carried in egg and sperm cells

 

plasmid: small self-duplication loop of DNA in a prokaryotic cell that is separate from the main chromosome and contains from one to a few genes

 

recombinant DNA: a molecule of DNA that includes genetic material from different sources

 

restriction endonuclease: type of restriction enzyme that recognizes a specific, short sequence of nucleotides within, rather than at the ends of, a strand of DNA, and then cuts the strand at that particular point within the sequence

 

restriction enzyme: an enzyme that cuts DNA at specific nucleotide sequences creating fragments

 

restriction fragment: a small segment of DNA cut from a DNA molecule by restriction endonucleases

 

restriction site: a specific location within a short sequence of nucleotides in a strand of DNA where restriction endonucleases will cut

 

somatic gene therapy: therapy that is aimed at correcting genetic disorders in somatic (body) cells

 

sticky end: a short sequence of unpaired nucleotides remaining at each end of a restriction fragment on a single strand of DNA after an endonuclease makes a staggered cut at the restriction site

 

target sequence: in DNA replication, a short sequence of nucleotides within a strand of DNA recognized and cut by restriction endonucleases

 

transgenic organism: produced by incorporating the DNA from one organism into another to create a new genetic combination