1. 3.5 – Genetic Modification & Biotechnology

2. Essential Idea: Biologists have developed techniques for artificial manipulation of DNA, cells and organisms.
3.5
Genetic Modification and Biotechnology
Understandings:
Gel electrophoresis is used to separate proteins or fragments of DNA according to size
PCR can be used to amplify small amounts of DNA
DNA profiling involves comparison of DNA
Gene modification is carried out by gene transfer between species
Clones are groups of genetically identical organisms, derived from a single original parent cell
Many plant species and some animal species have natural methods of cloning
Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells
Methods have been developed for cloning adult animals using differentiated cells
Applications:
Use of DNA profiling in paternity and forensics investigations
Gene transfer to bacteria using plasmids makes use of restriction endonucleases and DNA ligase
Assessment of the potential risks and benefits associated with genetic modification of crops
Productions of cloned embryos produced by somatic-cell nuclear transfer
Skills:
Design an experiment to assess one factor affecting the rooting of stem-cuttings
Analyze examples of DNA profiles
Analyze data on risks to monarch butterflies of Bt crops

3. Review the steps of DNA Replication
WITH A PARTNER:
Review the steps of DNA Replication

4. PCR – Polymerase Chain Reaction
For other techniques, substantial quantities of DNA are necessary
PCR is used to make millions of copies of a DNA sample so that other biotechnologies can be done

5. template DNA (DNA to be copied)
Requirements
template DNA (DNA to be copied)
a thermostable form of the DNA polymerase III enzyme from a thermophilic bacteria (Taq polymerase)
Primers
free-floating nucleotides (deoxynucleoside triphosphates – dNTPs)

6. II. Gel Electrophoresis -Used to separate fragments of DNA

7. A. Restriction enzymes (endonucleases) are used
A. Restriction enzymes (endonucleases) are used to cut up DNA into fragments of varying sizes
-Cut DNA at specific sites (restriction sites) – usually palindromes
-Found naturally in bacteria – used to cut up invading viral DNA
-Once DNA is cut, results in restriction fragments with sticky ends

8. B. Fragments placed in holes at one end of a slab of charged gel

9. C. DNA fragments move through gel towards positive pole D
C. DNA fragments move through gel towards positive pole D. Smaller pieces of DNA move farther faster than larger pieces creating a banded pattern
Discuss as a table: WHY do DNA fragments move towards the positive pole? WHY do smaller pieces move farther and faster than larger ones?

10. DNA Profiling/Fingerprinting
A. Match an unknown sample of DNA with a known sample
B. If patterns are the same = same person
Patterns similar = probably related

11. C. Often use non-coding sections of DNA the include STRs (short tandem repeats)

12. D. Used for paternity testing, criminal
D. Used for paternity testing, criminal investigations, determining evolutionary and ecological relationships

13. V. Gene Transfer A. AKA gene modification or gene cloning – take a gene out of one organism and place it into a different organism 1. Used to create cold- and pest-resistant crops B. REMEMBER – Universal Genetic Code

14. Discuss as a table: What might be some of the downsides of this type of technology?

15. C. Steps of Gene Cloning
Gene of interest identified and isolated (ex.insulin)
-Also need a cloning vector which will carry the gene – most often a bacterial plasmid

16. 2. Gene of interest and vector are cut with the same restriction enzymes, resulting in complimentary sticky ends

17. 3. The target DNA is fused into the plasmid using DNA ligase
4. The vector carrying the gene of interest is introduced into bacterial cells by transformation

18. 5. Select for cells that have been transformed – usually gene of interest is linked to gene for antibiotic resistance and then the bacteria is grown on plates containing antibiotics – only the cells that have taken up the new plasmid grow

20. Cloning
A. Many plants and some animals have natural methods of cloning

21. B. Reproductive cloning - Making copies of whole organisms

22. C. Therapeutic cloning - Making copies of embryonic/adult stem cells (AKA stem cell research) 1. Its aim is to develop cells which have not yet gone through the process of differentiation

23. Ethical Issues surrounding therapeutic cloning
a. Therapeutic cloning starts with production of human embryos - Is it ethically acceptable to generate a new human embryo for the sole purpose of medical research?
b. In nature, embryos are created only for reproduction and many people believe that using them for experiments is unnatural and wrong
c. Embryonic stem cells has led to major breakthroughs in human biology
d. Scientists are coming closer and closer to growing skin to repair serious burns, growing new heart muscle to repair an ailing heart, growing new kidney tissue to rebuild a failing kidney
e. With rare exceptions, the vast majority of researchers are against the idea of reproductive cloning in humans

24. DISCUSS AS A TABLE
While showing utmost respect for different and opposing views, discuss the pros and cons of therapeutic cloning. Share your own opinions if you wish, but be polite!