molecular clock


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molecular clock

n.
1. An assumed approximately constant rate of change over evolutionary time in the nucleotide sequences of DNA molecules and the amino acid sequences of protein molecules.
2. A technique based on this assumption, in which the amount of time since two species or other taxa diverged from a common ancestor is estimated by measuring the number of differences between certain gene or protein sequences of the taxa.
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Molecular genome has captured by molecular biologists for characterization and extensively used as molecular clocks (Bromham, 2003), even can be used where no fossils records are available.
A recently developed relaxed molecular clock method, called RelTime, was used by researchers from universities of Oakland in Michigan and Temple in Philadelphia, who concluded the birth of first animals to have taken place about 1.
The strict molecular clock was rejected in favour of the relaxed clock in all the population growth models tested.
At the cellular level, circadian rhythms originate from self-sustained, autoregulated, cyclic expressions of clock genes, which constitute the molecular clock.
In addition, AhR signaling affects molecular clock genes to influence glucose metabolism.
2006) are "inconsistent" and how this affects the results of molecular clock dating analyses and inferred diversification patterns.
That has led many scientists to view telomere length as a marker of biological aging, a molecular clock ticking off the cell's life span, as well as an indicator of overall health.
Studies that looked at pieces of mitochondrial DNA, a type of genetic material that can be used as a molecular clock to measure the time since two genetic lineages split, concluded that the various killer whale groups are similar enough to fall into a single species.
Interesting facts are scattered throughout the book, such as how scientists determine the diets of fossilized organisms, how the molecular clock of neutral mutations can determine the time elapsed since a split from common ancestors, the evolution of complex adaptations (venom before fangs, and probably before snakes), the development of feathers from genes that originally produced scales, and the evolution of the complex eye, to name a few examples.
We present analysis of preliminary mitochondrial and nuclear DNA data using a relaxed molecular clock approach with Bayesian analysis.
That disagreement between the dates from the fossil imprints and the dates from the molecular clocks caused some scientists to wonder whether the molecular clock calculations were wrong.

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