Genetics is the study of heredity and variations. Heredity and variations are controlled by genes—what they are, what they do, and how they work. Genes inside the nucleus of a cell are strung together in such a way that the sequence carries information: that information determines how living organisms inherit various features (phenotypic traits). For example, offspringproduced by sexual reproduction usually look similar to each of their parents because they have inherited some of each of their parents' genes. Genetics identifies which features are inherited, and explains how these features pass from generation to generation. In addition to inheritance, genetics studies how genes are turned on and off to control what substances are made in a cell—gene expression; and how a cell divides—mitosis or meiosis.
Some phenotypic traits can be seen, such as eye color while others can only be detected, such as blood type or intelligence. Traits determined by genes can be modified by the animal's surroundings (environment): for example, the general design of a tiger's stripes is inherited, but the specific stripe pattern is determined by the tiger's surroundings. Another example is a person's height: it is determined by both genetics and nutrition.
Chromosomes are tiny packages which contain one DNA molecule and its associated proteins. Humans have 46 chromosomes (23 pairs). This number varies between species—for example, many primates have 24 pairs. Meiosis creates special cells, sperm in males and eggs in females, which only have 23 chromosomes. These two cells merge into one during the fertilization stage of sexual reproduction, creating a zygote. In a zygote, a nucleic acid double helix divides, with each single helix occupying one of the daughter cells, resulting in half the normal number of genes. By the time the zygote divides again, genetic recombination has created a new embryo with 23 pairs of chromosomes, half from each parent. Mating and resultant mate choice result in sexual selection. In normal cell division (mitosis) is possible when the double helix separates, and a complement of each separated half is made, resulting in two identical double helices in one cell, with each occupying one of the two new daughter cells created when the cell divides.
Chromosomes all contain DNA made up of four nucleotides, abbreviated C (cytosine), G (guanine), A (adenine), or T (thymine), which line up in a particular sequence and make a long string. There are two strings of nucleotides coiled around one another in each chromosome: a double helix. C on one string is always opposite from G on the other string; A is always opposite T. There are about 3.2 billion nucleotide pairs on all the human chromosomes: this is the human genome. The order of the nucleotides carries genetic information, whose rules are defined by the genetic code, similar to how the order of letters on a page of text carries information. Three nucleotides in a row—a triplet—carry one unit of information: a codon.
The genetic code not only controls inheritance: it also controls gene expression, which occurs when a portion of the double helix is uncoiled, exposing a series of the nucleotides, which are within the interior of the DNA. This series of exposed triplets (codons) carries the information to allow machinery in the cell to "read" the codons on the exposed DNA, which results in the making of RNA molecules. RNA in turn makes either amino acids or microRNA, which are responsible for all of the structure and function of a living organism; i.e. they determine all the features of the cell and thus the entire individual. Closing the uncoiled segment turns off the gene.
Answer:
The gatherings of the philosophical group called peripatetics led in music subject by Aristoxenus, helped drive such innovations as the development of major-minor tonality, the development of equal-tempered tuning, and the recreation of the musical styles of Ancient Greece.
Explanation:
Aristoxenus was born in 375 bc in Tarentum, a Greek city in southern Italy and belonged to the group of philosophers called Peripatetics.
He is considered currently the most relevant music´s theorist in the classical world due to his empirical approach given in his work called Elementa harmonica where he vastly wrote about equal-tempered tuning and major-minor tonality and how these are related to the human soul as harmony and how they needed to be evaluated as a sole system by ear voiding cosmology and ethics. He seemed to follow Pythagorean theory
Aristoxenus flourished in the time of Alexander the Great who reigned in 336-323 and he was Aristotle´s pupil too.
Nowadays he became a key source for the study of ancient Greek music styles
. It is said that he gave birth to musicology.
Currier and Ivy are reprinted on many Christmas cards.
