Biology Chapter 12

Gel Electrophoresis

A method for sorting macromolecules, usually proteins or nucleic acids, primarily by their electrical charge and size.

Genetically modified foods

Account for a significant percentage of several staple crops in the U.S., Argentina, and Brazil. Controversy about the safety of these foods is an important political issue. Opponents are concerned that carrying genes from other species might harm the environment or be hazardous to human health. In the U.S., all genetic engineering projects are evaluated by a number of regulatory agencies including the Food and Drug Administration, Environmental Protection Agency, National Institutes of Health, and Department of Agriculture.

Plasmids

Circular DNA molecules that duplicate separately from the larger bacterial chromosome. They are the key tools for gene cloning, the production of multiple identical copies of a gene-carrying piece of DNA.

Recombinant DNA

Constructed by combining pieces of DNA from two different sources to form a single DNA molecule. Recombinant DNA technology is widely used in genetic engineering. Recombinant DNA is produced by combining two ingredients: a bacterial plasmid and the gene of interest. Bacterial enzymes called restriction enzymes are the cutting tools used for making recombinant DNA. The restriction enzyme recognizes a specific restriction site in the DNA, binds to it, cuts the two strands of DNA by breaking the chemical bonds at specific points.

Other pharmaceutical applications

DNA technology is used to produce medically valuable molecules, such as human growth hormone (HGH), the hormone erythropoietin (EPO), which stimulates production of red blood cells, and vaccines.

The human genome

Genomics is the study of complete sets of genes (genomes) Begun in 1990, the Human Genome Project was a scientific endeavor to determine the nucleotide sequence of all the DNA in the human genome and identify the location and sequence of every gene. At the completion of the project, more than 99% of the genome had been determined, about 3 billion nucleotide pairs were identified, about 21,000 genes were found, and about 98% of the human DNA was identified as noncoding. Some of this noncoding DNA is made up of gene control sequences such as promoters, enhancers, and microRNAs. Other noncoding regions include introns and repetitive DNA. Scientists have begun to gather sequence data from our extinct relatives. In 2013, scientists sequenced the entire genome of a Neanderthal. The resulting genome was nearly as complete as that from a modern human. The analysis revealed evidence of interbreeding with Homo sapiens. A 2014 study provided evidence that many present-day humans of European and Asian descent carry Neanderthal-derived genes. Comparisons with human DNA and and chimpanzee DNA revealed that we share 96% of our genome.

Humulin

Humulin is human insulin produced by genetically modified bacteria. In humans, insulin is a protein normally made by the pancreas. In the past, diabetes was treated using insulin from cows and pigs. In 1978, scientists working at a biotechnology company chemically synthesized DNA fragments and linked them to form the two genes that code for the two polypeptides that make up human insulin. They then inserted these artificial genes into E. coli host cells. The bacteria produced large quantities of humulin and allowed it to hit the market as the world's first genetically engineered pharmaceutical product.

Human gene therapy

Intended to treat disease by introducing genes into an afflicted person. A person with a single defective gene may be treated by replacing or supplementing the mutant gene with the normal allele. This could potentially correct a genetic disorder, perhaps permanently.

Genetically modified organisms

Organisms that have acquired one or more genes by artificial means In the U.S. more than 80% of the corn crop, more than 90% of the soybean crop, and about 75% of the cotton crop are genetically modified. Plants are modified to be insect-resistant to reduce the need for chemical insecticides. Genetic engineering is also used to improve the nutritional value of crop plants. "Golden rice 2" is a transgenic variety of rice that could help prevent vitamin A deficiency and resulting blindness, especially in developing nations that depend on rice as a staple crop. Cassava is a starchy root crop that has been modified to produce increased levels of iron and beta-carotene. AquAdvantage is a trade name for Atlantic salmon that have been genetically modified to reach market size in half the normal time. It may become the first GM animal approved for consumption in the U.S.

Transgenic organisms

Organisms that have acquired one or more genes from another organism of another speicies

Short tandem repeat (STR) analysis

Repetitive DNA makes up much of the DNA that lies between genes in humans and consists of nucleotide sequences that are present in multiple copies in the genome. Short tandem repeats are short sequences of DNA repeated many times, tandemly (one after another), in the genome. STR analysis is a method of DNA profiling that compares the lengths of STR sequences at specific sites in the genome. To create a DNA profile, a scientist uses PCR to amplify the regions of DNA that include STR sites which are then compared.

DNA sequencing

Researchers can exploit the principle of complementary base pairing to determine the complete nucleotide sequence of a DNA molecule, a process called DNA sequencing.

Polymerase chain reaction (PCR)

Technique by which a specific segment of DNA can be amplified: targeted and copied quickly and precisely. It permits a scientist to obtain enough DNA from tiny amounts of blood or other tissue to allow the construction of a DNA profile.

DNA profiling

The analysis of DNA samples to determine whether they come from the same individual; has rapidly transformed the field of forensics, the scientific analysis of evidence for crime scene investigations and other legal proceedings. To produce a DNA profile, scientists compare sequences in the genome that vary from person to person. DNA profiling can be used to identify murder victims, settle a question of paternity, and prove the origin of contraband animal products.

Bioinformatics

The application of computational methods to the storage and analysis of biological data.

Genetic engineering

The direct manipulation of genes for practical purposes To manipulate genes in the laboratory, biologists often use bacterial plasmids.

Biotechnology

The manipulation of organisms or their components to make useful products; genetic engineering

Gene cloning

The production of multiple identical copies of a gene-carrying piece of DNA. Gene cloning methods are essential to the production of GMO's.