DNA

Deoxyribonucleic acid (ⁱ/diˈɒksiˌraɪboʊnjʊˌkliːɪk, -ˌkleɪɪk/;DNA) is a molecule that carries most of the genetic instructions used in the development, functioning and reproduction of all known living organisms and many viruses. DNA is a nucleic acid; alongside proteins and carbohydrates, nucleic acids compose the three major macromolecules essential for all known forms of life. Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since they are composed of simpler units called nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase—either cytosine (C), guanine (G), adenine (A), or thymine (T)—as well as a monosaccharide sugar called deoxyribose and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. According to base pairing rules (A with T, and C with G), hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 10³⁷, and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC (trillion tons of carbon).

City

A city is a large and permanent human settlement. Although there is no agreement on how a city is distinguished from a town in general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.

Cities generally have complex systems for sanitation, utilities, land usage, housing, and transportation. The concentration of development greatly facilitates interaction between people and businesses, benefiting both parties in the process, but it also presents challenges to managing urban growth.

A big city or metropolis usually has associated suburbs and exurbs. Such cities are usually associated with metropolitan areas and urban areas, creating numerous business commuters traveling to urban centers for employment. Once a city expands far enough to reach another city, this region can be deemed a conurbation or megalopolis. In terms of population, the largest city proper is Shanghai, while the fastest-growing is Dubai.

Origins

There is not enough evidence to assert what conditions gave rise to the first cities. Some theorists have speculated on what they consider suitable pre-conditions and basic mechanisms that might have been important driving forces.

Bongo drum

Bongos (Spanish: bongó) are an Afro-Cuban percussion instrument consisting of a pair of small open bottomed drums of different sizes. In Spanish the larger drum is called the hembra (female) and the smaller the macho (male). Together with the conga or tumbadora, and to a lesser extent the batá drum, bongos are the most widespread Cuban hand drums, being commonly played in genres such as Cuban son, salsa and Afro-Cuban jazz.

History

Origins

The origin of the bongo is largely unclear. Its use was first documented in the Eastern region of Cuba, the Oriente Province, during the late 19th century, where it was employed in popular music styles such as nengón, changüí, and their descendent, the Cuban son.

Most sources on Afro-Cuban cultural history argue that the bongo derives from Central African (Congo/Bantu) drum models, noticeable in the open bottoms. Also a Santería influence from Yoruba culture in the symbolic "twin" drum is assumed. The strong historical presence of Africans from the Congo/Angola region in Eastern Cuba (where the bongo first appeared) makes such an influence probable. Moreover, Central African/Congo influences are also documented in the Cuban son music genre, including changüí, and initially the development of the bongo drum went parallel with these genres. From such conceptual African drum models, the bongo developed further in Cuba itself, and some historians state that the attaching of the two drums was a later invention that took place in Cuba.

Cincinnati Zoo and Botanical Garden

The Cincinnati Zoo and Botanical Garden is the second oldest zoo in the United States and is located in Cincinnati, Ohio. It opened in 1875, just 14 months after the Philadelphia Zoo on July 1, 1874. The Reptile House is the oldest zoo building in the United States, dating from 1875.

The Cincinnati Zoo is located in the Avondale neighborhood of Cincinnati . It was founded on 65.4 acres (26.5 ha) in the middle of the city, and since then it has acquired some of the surrounding blocks and several reserves in Cincinnati's outer suburbs. The zoo conducts breeding programs, and was the first to successfully breed California sea lions. The zoo also has other breeding programs including South African cheetahs, Sumatran rhinoceros, Indochinese tigers, Malayan tigers, western lowland gorillas, pottos, and Masai giraffes. The Cincinnati Zoo was the home of Martha, the last living passenger pigeon, which died there in 1914. It was also home to the last living Carolina parakeet in 1918.