If the exchange of one phone in a word for another gives a new word with a different meaning, then the two phones belong to different phonemes. The difference in meaning between the English words kill and kiss is a result of the exchange of the phoneme /l/ for the phoneme /s/ . Two words that differ in meaning through a contrast of a single phoneme form a minimal pair. Within linguistics there are differing views as to exactly what phonemes are and how a given language should be analyzed in phonemic (or phonematic) terms.
Also known as epigenetic clock, DNA clock, Horvath's clock or DNA methylation age, this biological aging clock is an age predictor that can be used to measure the age of most human tissues, cell types, or organs.orvath hypothesized that DNA methylation age measures the cumulative effect of an epigenetic maintenance system but details are unknown. The fact that DNA methylation age of blood predicts all-cause mortality in later life suggests that it relates to a process that causes aging.
Ageing (British English) or aging (American English) is the process of becoming older. In the narrow sense, the term refers to biological ageing of human beings, animals and other organisms.In the broader sense, ageing can refer to single cells within an organism (cellular senescence) or to the population of a species (population ageing). Accumulative-waste theory: The biological theory of ageing that points to a buildup in cells of waste products that presumably interfere with metabolism. 2  Evidence supporting this theory is the presence of a waste product called lipofuscin leading to age pigment.