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Chapter 20 Blog: Genetic Technology (Suma)

Page history last edited by Suma Gondi 12 years, 11 months ago

This chapter was about different types genetic technology, or using laboratory techniques to isolate and manipulate DNA fragments, also known as recombinant DNA technology.  Gene cloning is when multiple copies of a gene are made, either to study that gene or obtain a lot of product from it.  This process is started with isolating a vector and a gene of interest with restriction enzymes, which cut at sites that are the reverse on either side of the DNA, and allowing the DNA fragments to bind to each other, sealing the ends with ligase.  Then inserting this vector/gene combination into a host cell.  The cell then begins to replicate the vector and divides to form many cells.  A collection of recombinant vectors with unique chromosomal DNA is added to bacterial cells to create a DNA library.  A cDNA library is when cDNA from mRNA is used instead. 


A way to separate DNA fragments would be through gel electrophoresis, where DNA is passed through a gel that sorts by size, charge, and mass, making comparisons across samples simpler.  Another technique used to amplify the copies of a gene is PCR, which uses DNA polymerase and primers to make many copies.  To determine the base sequence of DNA, the dideoxy chain-termination method or dideoxy sequencing is used. 


Biotechnology is the use of living organisms to benefit humans, and began around 12000 years ago with the domestication of livestock.  More recently, molecular genetics have been applied.  For example, human insulin can be made by recombinant bacteria, by having the A and B coding sequences inserted into a bacterium like E. coli, extracting fusion proteins and removing B-galactosidase, and purifying the A and B chain to form the protein.  Previous to this technique, insulin was isolated from cattle, however some people were allergic to it.  


Bioremediation is the use of microorganisms or plants to detoxify pollutants in the environment, through the use of enzymes produced by the organism that could alter or transform its toxic pollutant structure.  A transgenic organism carries genes that are introduced through gene cloning, making them genetically modified organisms.  Gene replacement is when one cloned gene combines with a normal gene, creating a heterozygote, and gene knockout is when a cloned gene has a mutation that inactivates function, creating a homozygote that does not have the gene function.  As a side note- when I went to the labs in the University of Maryland, some of the mice there had undergone gene knockout and had a gene that encodes for a protein that functions in the hippocampus removed.  As a result, when placed in a maze that they had completed before, they were not able to do it again.


Molecular pharming is the production of medically important proteins in livestock mammary glands, because certain proteins are more likely expressed in mammals.  Mammals are able to undergo post-translational modification, avoid the degradation and improper folding in bacteria, and produce a high yield.  Genomics is the study of the genome of a species, while functional genetics is the study of expressed genes.   


Useful Links:


1)  This YouTube video explains the process of PCR, which is used to make multiple copies of DNA in  a short period of time.

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2)  Analysis of Telomere Length in Dolly: This PubMed article talks about the length of the telomeres in Dolly, who was the first cloned animal.  The telomere length was lower than normal.  This decrease was consistant with the amount the telomeres would have degraded in vitro, showing that cloning may not restore telomeres.


3)  This image details the process of genetic engineering.



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