Biology and Society: Crime Scene Investigations: Murders in a Small Town On November 22,1983
- A 15-year-old girl was raped and murdered on a quiet country lane. - Three years later, another 15-year-old girl was raped and murdered.
DNA fingerprinting of DNA samples from suspects and the crime scene - Proved one man guilty and another man innocent.
Recombinant DNA Technology
Recombinant DNA technology is a set of techniques for combining genes from different sources into a single DNA molecule. (Figure 1) - An organism that carries recombinant DNA is called a genetically modified (GM) organism.
Recombinant DNA technology is applied in the field of biotechnology. - Biotechnology uses various organisms to perform practical tasks
From Humulin To Genetically Modified Foods
By transferring the gene for a desired protein product into a bacterium, proteins can be produced in large quantities.
In 1982, the world’s first genetically engineered pharmaceutical product was produced. - Humulin, human insulin, was produced by genetically modified bacteria.
Humulin was the first recombinant DNA drug approved by the FDA.
DNA technology is also helping medical researchers develop vaccines. -A vaccine is a harmless variant or derivative of a pathogen. - Vaccines are used to prevent infectious diseases.
Genetically Modified (GM) Foods
Today, DNA technology is quickly replacing traditional plant-breeding programs. Corn has been genetically modified to resist insect infestation. -This corn has been damaged by the European corn borer. (Figure 3) “Golden rice” has been genetically modified to contain beta-carotene. (Figure 4) - Our bodies use beta-carotene to make vitamin A.
Farm Animals and “Pharm” Animals
While transgenic plants are used today as commercial products, transgenic whole animals are currently only in the testing phase. These transgenic sheep carry a gene for a human blood protein. (Figure 5) -This protein may help in the treatment of cystic fibrosis.
While transgenic animals are currently used to produce potentially useful proteins, none are yet found in our food supply. It is possible that DNA technology will eventually replace traditional animal breeding.
Recombinant DNA Technology
Bacteria are the workhorses of modern biotechnology.
To work with genes in the laboratory, biologists often use bacterial plasmids. - Plasmids are small, circular DNA molecules that are separate from the much larger bacterial chromosome. (Figure 6) Plasmids can easily incorporate foreign DNA.
Plasmids are readily taken up by bacterial cells.
-Plasmids then act as vectors, DNA carriers that move genes from one cell to another.
A Closer Look: Cutting and Pasting DNA with Restriction Enzymes Recombinant DNA is produced by combining two ingredients:
-A bacterial plasmid
- The gene of interest
To combine these ingredients, a piece of DNA must be spliced into a plasmid. This splicing process can be accomplished using restriction enzymes. (Figure 7) - These enzymes cut DNA at specific nucleotide sequences.
These cuts produce pieces of DNA called restriction fragments. -That may have “sticky ends” that are important for joining DNA from different sources.
DNA Fingerprinting and Forensic Science
DNA technology has rapidly revolutionized the field of forensics. - Forensics is the scientific analysis of evidence from crime scenes DNA fingerprinting can be used to determine whether or not two samples of genetic material are from a particular individual. (Figure 8)
Murder, Paternity, and Ancient DNA
-Has become a standard criminology tool.
- Has been used to identify victims of the September 11, 2001, World Trade Center attack. - Can be used in paternity cases.
DNA fingerprinting is also used in evolutionary research.
The polymerase chain reaction (PCR) is a technique by which any segment of DNA can be copied...