Circular chromosomeA circular chromosome is a chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromosome of most eukaryotes. Most prokaryote chromosomes contain a circular DNA molecule – there are no free ends to the DNA. Free ends would otherwise create significant challenges to cells with respect to DNA replication and stability. Cells that do contain chromosomes with DNA ends, or telomeres (most eukaryotes), have acquired elaborate mechanisms to overcome these challenges.
ChromatographyIn chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the mobile phase, which carries it through a system (a column, a capillary tube, a plate, or a sheet) on which a material called the stationary phase is fixed. Because the different constituents of the mixture tend to have different affinities for the stationary phase and are retained for different lengths of time depending on their interactions with its surface sites, the constituents travel at different apparent velocities in the mobile fluid, causing them to separate.
Paper chromatographyPaper chromatography is an analytical method used to separate coloured chemicals or substances. It is now primarily used as a teaching tool, having been replaced in the laboratory by other chromatography methods such as thin-layer chromatography (TLC). The setup has three components. The mobile phase is a solution that travels up the stationary phase, due to capillary action. The mobile phase is generally a mixture of non-polar organic solvent, while the stationary phase is polar inorganic solvent water.
Reading frameIn molecular biology, a reading frame is a way of dividing the sequence of nucleotides in a nucleic acid (DNA or RNA) molecule into a set of consecutive, non-overlapping triplets. Where these triplets equate to amino acids or stop signals during translation, they are called codons. A single strand of a nucleic acid molecule has a phosphoryl end, called the 5′-end, and a hydroxyl or 3′-end. These define the 5′→3′ direction. There are three reading frames that can be read in this 5′→3′ direction, each beginning from a different nucleotide in a triplet.
Eternal youthEternal youth is the concept of human physical immortality free of ageing. The youth referred to is usually meant to be in contrast to the depredations of aging, rather than a specific age of the human lifespan. Eternal youth is common in mythology, and is a popular theme in fiction. Eternal youth is a characteristic of the inhabitants of Paradise in Abrahamic religions. The Hindus believe that the Vedic and the post-Vedic rishis have attained immortality, which implies the ability to change one's body's age or even shape at will.
