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  2. Overlapping gene - Wikipedia

    en.wikipedia.org/wiki/Overlapping_gene

    The current definition of an overlapping gene varies significantly between eukaryotes, prokaryotes, and viruses. [2] In prokaryotes and viruses overlap must be between coding sequences but not mRNA transcripts, and is defined when these coding sequences share a nucleotide on either the same or opposite strands.

  3. Ball-and-stick model - Wikipedia

    en.wikipedia.org/wiki/Ball-and-stick_model

    Hofmann's 1865 ball-and-stick model of methane (CH 4). Later discoveries disproved this geometry. In 1865, German chemist August Wilhelm von Hofmann was the first to make ball-and-stick molecular models. He used such models in lecture at the Royal Institution of Great Britain. Specialist companies manufacture kits and models to order.

  4. Methyl group - Wikipedia

    en.wikipedia.org/wiki/Methyl_group

    In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula CH 3 (whereas normal methane has the formula CH 4). In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many organic compounds. It is a very stable group in ...

  5. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    Molecules, by definition, are most often held together with covalent bonds involving single, double, and/or triple bonds, where a "bond" is a shared pair of electrons (the other method of bonding between atoms is called ionic bonding and involves a positive cation and a negative anion).

  6. Orbital overlap - Wikipedia

    en.wikipedia.org/wiki/Orbital_overlap

    The overlap matrix is a square matrix, used in quantum chemistry to describe the inter-relationship of a set of basis vectors of a quantum system, such as an atomic orbital basis set used in molecular electronic structure calculations. In particular, if the vectors are orthogonal to one another, the

  7. Structural biology - Wikipedia

    en.wikipedia.org/wiki/Structural_biology

    Currently, solid-state NMR is widely used in the field of structural biology to determine the structure and dynamic nature of proteins (protein NMR). [ 15 ] In 1990, Richard Henderson produced the first three-dimensional, high resolution image of bacteriorhodopsin using cryogenic electron microscopy (cryo-EM). [ 16 ]

  8. Methane - Wikipedia

    en.wikipedia.org/wiki/Methane

    Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest-energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this energy level is a triply degenerate ...

  9. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    Non-polar covalent bonds in methane (CH 4). The Lewis structure shows electrons shared between C and H atoms. Covalent bonding is a common type of bonding in which two or more atoms share valence electrons more or less equally. The simplest and most common type is a single bond in which two atoms share two electrons.