Glucose (source code)
= Glucose
{title2=$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$}
{wiki}
<Glucose> is a <monosaccharide> with <molecular formula> $\mathrm C_6\mathrm H_{12}\mathrm O_6$. Its familiar biological form, D-glucose, is an <aldohexose>. In the open-chain <Fischer projection>, $\mathrm{CHO}$ is at the top and $\mathrm{CH}_2\mathrm{OH}$ at the bottom; the <hydroxy groups> at C2, C3, C4, and C5 point right, left, right, right. This full pattern distinguishes D-<glucose> from other six-<carbon> <aldehyde> <sugars>. See https://openstax.org/books/organic-chemistry/pages/25-4-configurations-of-the-aldoses[McMurry, Organic Chemistry, 25.4: configurations of the aldoses].
\Image[/glucose-fischer-projection.png]
{title=D-<glucose>: six <carbon> positions and four open-chain <stereocenters>}
{description=Horizontal <chemical bonds> point toward the viewer; vertical <chemical bonds> point away. The <hydroxy group> pattern from C2 through C5 is right/left/right/right. $\mathrm{CHO}$ and $\mathrm{CH}_2\mathrm{OH}$ are condensed end groups. The diagram records an open-chain reference structure, not the predominant form in an aqueous <chemical solution>.}
The <molecular formula> can be checked directly: one $\mathrm{CHO}$ group, four $\mathrm{CHOH}$ groups, and one $\mathrm{CH}_2\mathrm{OH}$ group give six <carbon>, twelve <hydrogen>, and six <oxygen> <chemical atoms>. All four interior <carbon> positions are <stereocenters> in this open-chain structure. Neither their orientations nor the arrangement of <chemical bonds> can be recovered from the <molecular formula> alone.
In <water>, <glucose> exists mainly in six-membered rings in <chemical equilibrium> with a small amount of open-chain <glucose>. Ring closure connects the <hydroxy group> at C5 to the <aldehyde> carbon at C1; the ring contains five <carbon> <chemical atoms> and one <oxygen>, with C6 outside it. No <chemical atoms> are lost, so the <molecular formula> remains $\mathrm C_6\mathrm H_{12}\mathrm O_6$. See https://openstax.org/books/organic-chemistry/pages/25-5-cyclic-structures-of-monosaccharides-anomers[McMurry, Organic Chemistry, 25.5: cyclic structures of monosaccharides].
<Glucose> is useful both as a substrate in cellular <metabolism> and as a building block of <polysaccharides>. <Cellulose> chains assembled from <glucose> units help support plant <cell walls>. The same small <sugar> thus connects chemical fuel to a structural material; its role depends on how it is transformed or linked. See https://www.ncbi.nlm.nih.gov/books/NBK9879/[Cooper, The Cell: A Molecular Approach, the molecular composition of cells].
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