Long chains of molecules known as nucleotides, that perform important functions in the cell; two kinds of nucleic acids function in the cell, i.e., DNA and RNA.

 

Building blocks of DNA and RNA. Nucleotides are composed of phosphate, sugar and one of four bases, adenine, guanine, cytosine and uracil (RNA) or thymine (DNA). Three bases form a codon, which specifies a particular amino acid; amino acids are strung together to form proteins. Strings of thousands of nucleotides form a DNA or RNA molecule.

Central compartment in cells of higher organisms (eukaryotes); it houses most of the heritable genetic information in a cell in higher organisms.

Visible characteristics or traits of an organism, like a plant or an animal.

Independent, free-floating circular piece of DNA in a bacterium, capable of making copies of itself in the host cell. Plasmids can be used in recombinant DNA experiments to clone genes from other organisms and make large quantities of their DNA.

The function of the PCR method is to replicate and amplify a specific DNA sequence in a sample, even when the sequences are present in extremely low levels and in a complex mixture (such as a processed food item). PCR imitates the natural process of DNA synthesis and relies on the complementary specificity of the two strands that comprise the double helix structure of DNA. In addition, specific oligonucleotides (short DNA sequences) or "primers" that flank the region to be amplified, serve as binding sites for polymerase to initiate replication. Template (or test) DNA, primers, and DNA polymerase are all a part of the PCR reaction mixture. The process involves specific incubation temperatures and times and is referred to as thermal cycling. To begin the process, the DNA mixture is denatured in a brief heat treatment that will break apart the hydrogen bonds holding the two strands together. This will yield two single strands of complimentary DNA. The temperature of the reaction is decreased, which allows the primers to bind to their complementary DNA. In the final step of PCR, a temperature-resistant polymerase (TAQ polymerase) will carry out the polymerization step (replicating and amplifying the sequence between the primers). These primer extension products will serve as the template in the next cycle. The process is repeated, exponentially amplifying the target DNA sequence, until literally billions of copies are formed. Standard gel electrophoresis techniques are used to determine if the DNA sequence of the modified gene was amplified. The completed PCR DNA solution is loaded onto an agarose gel. An electric current is passed through the gel, such that charged DNA molecules will move through the gel at different rates dependent on their size. This results in segregation of the DNA fragments. A fluorescent molecule able to bind to the DNA allows for visualization of the PCR products in the gel under UV light.

 

Real-time PCR utilizes the same principles as conventional PCR (as defined above). The main difference is that real-time PCR introduces a fluorescent probe(s) that will specifically anneal (or bind) to the DNA and follow the 5' nuclease activity of the TAQ polymerase. The presence of the gene sequences in question is indicated by fluorescence. Raw data is analyzed after the approximately two hour thermal cycling process is complete. Because real-time analysis allows for continuous collection of data throughout the PCR reaction, and then provides final data based on the reading of the amount of fluorescence emitted, there is no need to perform gel electrophoresis.

 

A short sequence of DNA that is paired with one strand of the template DNA in the polymerase chain reaction (PCR) technique. In PCR testing, the primer is selected to be complementary to the target sequence of DNA. Without a DNA primer sequence a new DNA chain cannot be constructed as the polymerase requires a binding site on the DNA molecule.

Any of a class of high molecular weight polymer compounds composed of a variety of a-amino acids joined by peptide linkages. Via the synthesis (of this "chain") performed by ribosomes, each protein is the ultimate expression product of a gene.

 

During their synthesis (after emerging from cell´s ribosome), proteins may also be phosphorylated (i.e., a "phosphate group" is added to the protein molecule), glycosylated (i.e., one or more oligosaccharides is added onto the protein molecule), acetylated (i.e., one or more "acetyl groups" is added to the protein molecule), farnesylated (i.e., a "farnesyl group" is added to the protein molecule), ubiquinated (i.e., a ubiquitin "tag" is added to the protein molecule), sulfated (i.e., a "sulfate group" is added to the protein molecule), or otherwise chemically modified. Proteins are the "workhorses" of living systems and include enzymes, antibodies, receptors, peptide hormones, etc. Proteins in living organisms respond to changing environmental and other conditions by changing their location within cells, by getting cut into (specific) pieces, by changing which (other) molecules they will bind (adhere) to, etc. All of the amino acids commonly found in (each and every one of the) proteins have an asymmetric carbon atom, except the amino acid glycine. Thus the protein is potentially chiral in nature.

 

Qualitative analysis reports the presence of or absence of GMO material, bit will not quantify how much GMO is present.

Real-time quantitative analysis reports precise quantitative results of GMO content, for example: "3% GMO." Real-time quantification is currently only available for corn and soy based products.

Class of enzymes that cut DNA at specific locations identified by the sequence of the nucleotides. At the site of the cut other pieces of DNA, sometimes sharing the same recognition sequence, can be inserted next to the original location of the cut.

Chemical chains made up of the sugar ribose attached to nucleic acid molecules. Different types of RNA exist in cells, some of which serve as the immediate code for proteins, some of which are involved in the physical process of protein synthesis. RNA can also serve instead of DNA as the only genetic information in certain viruses.

 

Semi-quantitative analysis reports GMO content above, below, or between two or more thresholds, for expample: "greater than 1%," "less than 1% and greater than 0.1%," or "negative at 0.1%." Standard multiple thresholds include 0.1% and 1% GMO, 1% and 5% GMO. Grains may be tested at the thresholds 0.01% and 0.1 %.

Single-species GMO detection provides total GMO content of a single species and is most suitable for products such as grains, flours, soy isolates, etc., where there is a single source of GMO.