Discuss how the molecular clock hypothesis (gene clock, evolutionary Essay

Discuss how the molecular clock hypothesis (gene clock, evolutionary clock, or molecular clock) can be used to explain the diver - Essay Example This paper will discuss the manner in which the molecular clock hypothesis can be utilised to explain the divergence evident in species. The molecular clock hypothesis focuses on the idea that molecular evolution typically takes place at a roughly uniform rate over the course of time. The molecular clock bases its processes on the contention that to date the materialization of different species, it is assumed that the degree of molecular evolution is primarily homogeneous among duplicable proteins as well as species. The molecular clock, which focuses on the molecular clock hypothesis, refers to a system used in molecular evolution, which utilises fossil constraints, and the extent of molecular change achieved to foresee the time in geologic history when taxa diverged or two independent species diverged. In essence, the molecular clock approximates when key events such as radiation and speciation took place. The molecular information used to make these calculations primarily include nucleotide sequences for amino acid and DNA sequences in proteins (Ayala 1996, p. 11731). The molecular clock is also from time to time referred to as the evolutionary clock or gene clock. Rather than calculating hours, minutes and seconds, the molecular clock computes the extent of mutations and changes that build up within the genetic order of various species over time. This means that evolutionary biologists can take advantage of this data to conclude the method through which species evolve, and to construe the time when two species diverged, particularly with regard to the evolutionary timeline. The molecular clock is comparable to a normal wristwatch so as to appreciate how the molecular clock works in providing information on the divergence of species. Notably, while a wristwatch measures time from ticks, which are essentially regular changes in time (seconds), a molecular clock, on the other hand, measures time using random changes such as DNA mutations. The originators of th e molecular clock, biologist Emile Zucherkandl and chemist Linus Pauling posit that the concept of the molecular clock centres on the notion that although genetic mutations take place rather randomly, they typically occur at a moderately constant rate. As a consequence, the number of differences noted between any two gene sequences continues to increase with time. This led to the conception that the degree of mutations within a certain DNA stretch can be used effectively to measure the time of species divergence (Britten 1986, p. 1394). However, similar to other clocks, the molecular clock also needs to be calibrated. Therefore, setting a molecular clock starts with known information such as the fossil record for a certain species. Subsequently, when the rate of mutation is ascertained, calculating the species’ divergence time becomes rather straightforward. For instance, if the rate of mutation in a certain species is five every millennium and 25 mutations exist in the speci es’ DNA, then it becomes quite clear that the species’ sequences diverged five million years ago. A prominent element of molecular clocks

Micro analysis of Apocalyspe Now (1979) Essay Example | Topics and Well Written Essays - 1500 words

Micro analysis of Apocalyspe Now (1979) - Essay Example Inspired by the 1902 novel of Joseph Conrad, The Heart of Darkness, Apocalypse Now presents a story of a U.S. Army assassin, Captain Benjamin Willard in his final mission in Vietnam. Willard is tasked to take a voyage up the Nung River into Cambodia, for purposes of finding and killing a renegade Green Beret officer, Colonel Walter Kurtz. Kurtz, who is believed to have gone insane, leads a native Montagnard army in the commission of derange killings. The native army regards Kurtz as their ‘god’. Willard joins the troop of a Navy river patrol boat in order to reach Kurtz. As the journey of Willard continues, his crew comes across Lieutenant Colonel Bill Kilgore, chief of a U.S. Army helicopter cavalry group, who led the elimination of a Viet Cong colony to afford an entry point for the Patrol Boat River into the mouth of the Nung River. After several notable episodes of the journey, Willard finally reached the outpost of Kurtz, completing his mission and thereby gaining an acknowledgment of the natives as their new ‘god’. The chosen sequence depicts a part of the journey of battle-weary Captain Benjamin Willard to the ferocious profundity of war. The film sequence focuses on Willard’s mission to attack a Vietnamese village suspected of being an enemy stronghold, with the indispensable participation of Lieutenant Colonel Bill Kilgore, who takes Willard on an airborne foray utilizing several U.S. army gunships. The sequence begins on the sound of a trumpet signalling the commencement of the mission as depicted by the movement of the first helicopter gunship elevating from the ground, followed consecutively by the rest of the gunships. As the helicopters soar the sky, Wagner’s â€Å"Ride of the Valkyries† plays in the background. Here, the viewer is being initiated into the spectacle and awesome sight of war. As each of the helicopters ascends in the orange sky, showing overlapping shots of helicopters in tight formation