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DNA exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA forms, although only B-DNA and Z-DNA have been directly observed in functional organisms. [14] The conformation that DNA adopts depends on the hydration level, DNA sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and ...
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. [15] The basic component of biological nucleic acids is the nucleotide , each of which contains a pentose sugar ( ribose or deoxyribose ), a phosphate group, and a nucleobase . [ 16 ]
Thymine (present in DNA only) Uracil (present in RNA only) 5-carbon sugar which is called deoxyribose (found in DNA) and ribose (found in RNA). One or more phosphate groups. [1] The nitrogen bases adenine and guanine are purine in structure and form a glycosidic bond between their 9 nitrogen and the 1' -OH group of the deoxyribose.
The most known chemical elements whose covalent combinations make up most biological molecules on Earth. [2] All of these elements are nonmetals.. In animals in general, the four elements—C, H, N, and O—compose about 96% of the weight, and major minerals (macrominerals) and minor minerals (also called trace elements) compose the remainder.
In 1802 the term "metalloids" was introduced for elements with the physical properties of metals but the chemical properties of non-metals. [194] However, in 1811, the Swedish chemist Berzelius used the term "metalloids" [195] to describe all nonmetallic elements, noting their ability to form negatively charged ions with oxygen in aqueous ...
Three DNA conformations are believed to be found in nature, A-DNA, B-DNA, and Z-DNA. The "B" form described by James D. Watson and Francis Crick is believed to predominate in cells. [ 2 ] James D. Watson and Francis Crick described this structure as a double helix with a radius of 10 Å and pitch of 34 Å , making one complete turn about its ...
Gene structure is the organisation of specialised sequence elements within a gene.Genes contain most of the information necessary for living cells to survive and reproduce. [1] [2] In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene.