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Transformation
Transformation
Definition of Transformation:
- A change in a genotype or phenotype caused by the direct uptake of genetic material by a cell
- The successful introduction of DNA from another source
What happens during Transformation?
Bacteria can take in plasmids (small parts of DNA). These plasmids divide and multiply. The bacteria then takes on the characteristics that the foreign DNA codes for.
Figure 1: This shows plasmids containing foreign DNA entering a bacteria
Competent Bacteria vs. Incompetent
If the cell takes in the plasmids it is competent. If it can't it is incompetent but can be made competent.
The reason the plasmids can't enter is because the plasmids have a phosphate group that is negatively charged. The phospholipids in the cell membrane of the bacteria are also negative. Because of this, the like charges make them repel each other. Therefore, the plasmid can't enter. In this process, calcium ions (+) are used to neutralize these groups, which are negatively charged. The foreign DNA can then enter the plasmid.
The solution used in this process is Calcium chloride. The bacteria is placed in this solution. After being cooled, it is reheated then cooled quickly again. The rapid change in temperature also helps the plasmid to enter because the membrane is disrupted.
Antibiotic resistance is tested for in the bacteria. If it can grow on the certain antibiotic used in this process, then the gene that coded for the resistance has entered the bacteria and it is now competent. If it doesn't grow, the procedure didn't work.
Figure : This is a diagram showing the process of artificial transformation
Hybridization
Hybridization
Definition of DNA Hybridization:
- Used to identify cells that identify introduced plasmids in bacteria with the gene that is required/wanted.
Definition of a Hybridization Probe:
- A fragment of DNA that is used to detect the presence of complementary nucleotide sequences
How does is this process used?
This gene's DNA is used to identify it. It will pair with a hybridization probe, which is short strand of a complementary strand of DNA.
This can be used to isolate colonies of bacteria that have a certain gene.
Example: A bacteria containing a gene with the DNA for insulin production will pair with a complementary DNA strand that codes for insulin. The bacteria containing this gene can then be isolated into a colony and used for insulin production.
Figure 3: This shows a hybridization probe (red) pairing with its complementary DNA strand
Figure 4: This diagram also shows the DNA probe pairing with the target DNA a.k.a. the gene they are trying to isolate
Helpful videos:
These topics are available on page 373-374 in the Biologys 12 textbook
References:
DiGiuseppe, M., & Fraser, D. (2012). Biology 12. Toronto, Ont.: Nelson Education.
The Mechanism of Transformation with Competent Cells. (2014, June 13). Retrieved October 17, 2017, from https://youtu.be/7Ul9RVYG5CM
B. (2012, March 14). AP Biology Lab 6: Molecular Biology. Retrieved October 17, 2017, from https://www.youtube.com/watch?v=OZyFX9megs8
B. (2013, May 10). AP Biology Labs - part 2. Retrieved October 17, 2017, from https://www.youtube.com/watch?v=CMIdyMDHd78
Transformation (genetics). (n.d.). Retrieved October 17, 2017, from http://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/transformation-genetics
Untitled Presentation-2. (n.d.). Retrieved November 08, 2017, from http://www.authorstream.com/Presentation/jersey16-3213448-untitled-presentation/
Background Information. (n.d.). Retrieved November 08, 2017, from http://www.odec.ca/projects/2006/sidh6h2/bg.html
M. (2013, January 19). Retrieved November 08, 2017, from https://www.youtube.com/watch?v=1sMOv9TUiFg
Szauter, P. (n.d.). Recombinant DNA. Retrieved November 08, 2017, from http://www.discoveryandinnovation.com/BIOL202/notes/lecture22.html
Principles of Identification of DNA Sequence: 3 Principles. (2015, September 29). Retrieved November 08, 2017, from http://www.biologydiscussion.com/dna/dna-sequence/principles-of-identification-of-dna-sequence-3-principles/9975
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