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  2. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    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 ...

  3. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to attach and detach from each other is responsible for most of the physical changes observed in nature. Chemistry is the science that studies these changes.

  4. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H 2 O).

  5. Biomolecule - Wikipedia

    en.wikipedia.org/wiki/Biomolecule

    This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and John Kendrew in 1958, for which they received a Nobel Prize in Chemistry A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes . [ 1 ]

  6. Adenine - Wikipedia

    en.wikipedia.org/wiki/Adenine

    Adenine (/ ˈ æ d ɪ n iː n /, / ˈ æ d ɪ n ɪ n /) (symbol A or Ade) is a purine nucleotide base.It is one of the nucleobases in the nucleic acids, DNA and RNA.The shape of adenine is complementary to either thymine in DNA or uracil in RNA.

  7. Biochemistry - Wikipedia

    en.wikipedia.org/wiki/Biochemistry

    The open-chain form can be turned into a ring of carbon atoms bridged by an oxygen atom created from the carbonyl group of one end and the hydroxyl group of another. The cyclic molecule has a hemiacetal or hemiketal group, depending on whether the linear form was an aldose or a ketose. [38] In these cyclic forms, the ring usually has 5 or 6 atoms.

  8. Chemistry: A Volatile History - Wikipedia

    en.wikipedia.org/wiki/Chemistry:_A_Volatile_History

    Early 20th century chemist Henry Moseley speculated that the answer to the number of protons lay in the nucleus. By firing a radioactive source at copper, he was able to knock electrons from their atoms, releasing a burst of energy in the form of an x-ray. When measured, the x-rays always had the same energy, unique to copper.

  9. Creatine - Wikipedia

    en.wikipedia.org/wiki/Creatine

    Creatine is a naturally occurring non-protein compound and the primary constituent of phosphocreatine, which is used to regenerate ATP within the cell. 95% of the human body's total creatine and phosphocreatine stores are found in skeletal muscle, while the remainder is distributed in the blood, brain, testes, and other tissues.