Single-stranded Information and Courses from MediaLab, Inc.

Denaturing chemicals can be added to the acrylamides during formation of polyacrylamide gels. These additives keep the solutes or molecules in a denatured state during separation. Urea denatures double-stranded DNA to single-stranded DNA. A detergent, sodium dodecyl sulfate (SDS), denatures proteins. Adding SDS with heat denatures proteins to small, similar shaped particles and coats each so that protein structures are not reformed. SDS is usually added to the gel and the protein sample. Then the mixture of protein coated fragments moves through polyacrylamide gel pores with speed similar to a mixture of DNA fragments.

Because of ionized phosphate groups, both DNA and RNA will migrate in an electrical field with an appropriate buffer. They are negatively charged and will migrate to the anode. The speed of migration and separation achieved is based upon size with smaller molecules traveling faster. The shape of macromolecules, type of support medium, and electrophoresis method also vary the separation results. The isolated nucleic acid can be single-stranded or double-stranded and can fold into other structures. AGE, PAGE, and CE are the most common electrophoresis methods used in analysis of nucleic acids. Pulsed electric fields are needed to separate large fragments. The electrophoresis employed in blotting techniques enhance these discrimination techniques.

Term Definition Codon A three nucleotide base sequence that codes for an amino acid Genome The genetic code composed of 64 codons that code for 21 amino acids and 3 stop codons. (amino acids are the building blocks of proteins and stop codons stop the writing process much like a period at the end of a sentence) Nucleic acid Polymer made of monomers; two examples are RNA and DNA Transcription Process of transferring information from DNA into an RNA message Translation The formation of an amino acid from RNA Deoxyribonucleic Acid (DNA) A double-stranded polymer of nucleotides that houses genetic information Ribonucleic acid (RNA) Typically a single-stranded polymer that is much shorter than DNA but chemically similar with a few differences (e.g.- uracil replaces thymine). Replication Reproduction of DNA content from parent to daughter cell during cell division Amplification methods Techniques that increase the amount of the target, the detection signal, or the probe so that sequences are readily detected Fluorescence The emission of light at a longer wavelength when the light is excited at a shorter wavelength Oligonucleotide Short single-stranded nucleic acid Probe A nucleic acid used to identify a hybridization target Polymerase Chain Reaction (PCR) An amplification method performed in vitro