Glucose,,

If concentrated glucose solution used, the water potential inside yeast cells will be higher than glucose soluion. Then, water will move out of the yeast cells and yeast will die.

Glucose

From Wikipedia, the free encyclopedia

Jump to: navigation, search



Glucose


圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Glucose-2D-skeletal.png/200px-Glucose-2D-skeletal.png


圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Beta-D-glucose-3D-vdW.png/120px-Beta-D-glucose-3D-vdW.png


Chemical name
6-(hydroxymethyl)oxane-2,3,4,5-tetrol

Synonym for D-glucose
dextrose

Varieties of D-glucose
α-D-glucose; β-D-glucose

Abbreviations
Glc

Chemical formula
C6H12O6

Molecular mass
180.16 g mol−1

Melting point
α-D-glucose: 146°C
β-D-glucose: 150°C

Density
1.54 g cm−3

CAS number
50-99-7 (D-glucose)

CAS number
921-60-8 (L-glucose)

SMILES
C(C1C(C(C(C(O1)O)O)O)O)O

Glucose (Glc), a monosaccharide (or simple sugar), is one of the most important carbohydrates in biology. The cell uses it as a source of energy and metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respiration in both prokaryotes and eukaryotes.
Two isomers of the aldohexose sugars are known as glucose, only one of which (D-glucose) is biologically active. This form (D-glucose) is often referred to as dextrose (dextrose monohydrate), especially in the food industry. This article deals with the D-form of glucose. The mirror-image of the molecule, L-glucose, cannot be used by cells.





Contents[hide]

1 Structure

1.1 Isomers
2 Production

2.1 Natural
2.2 Commercial
3 Function

3.1 As an energy source
3.2 Glucose in glycolysis
3.3 As a precursor
4 Sources and absorption
5 See also
6 External links



[edit] Structure
Glucose (C6H12O6) contains six carbon atoms and an aldehyde group and is therefore referred to as an aldohexose. The glucose molecule can exist in an open-chain (acyclic) and ring (cyclic) form, the latter being the result of an intramolecular reaction between the aldehyde C atom and the C-5 hydroxyl group to form an intramolecular hemiacetal. In water solution both forms are in equilibrium, and at pH 7 the cyclic one is the predominant. As the ring contains five carbon atoms and one oxygen atom, which resembles the structure of pyran, the cyclic form of glucose is also referred to as glucopyranose. In this ring, each carbon is linked to an hydroxyl side group with the exception of the fifth atom, which links to a sixth carbon atom outside the ring, forming a CH2OH group.

[edit] Isomers
Aldohexose sugars have 4 chiral centers giving 24 = 16 optical stereoisomers. These are split into two groups, L and D, with 8 sugars in each. Glucose is one of these sugars, and L and D-glucose are two of the stereoisomers. Only 7 of these are found in living organisms, of which D-glucose (Glu), D-galactose (Gal) and D-mannose (Man) are the most important. These eight isomers (including glucose itself) are all diastereoisomers in relation to each other and all belong to the D-series.
An additional asymmetric center at C-1 (called the anomeric carbon atom) is created when glucose cyclizes and two ring structures, called anomers, can be formed — α-glucose and β-glucose. They differ structurally in the orientation of the hydroxyl group linked to C-1 in the ring. When D-glucose is drawn as a Haworth projection, the designation α means that the hydroxyl group attached to C-1 is below the plane of the ring, β means it is above. The α and β forms interconvert over a timescale of hours in aqueous solution, to a final stable ratio of α:β 36:64, in a process called mutarotation.


圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/a/af/Glucose_Fisher_to_Haworth.gif/150px-Glucose_Fisher_to_Haworth.gif



圖片參考：http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png
Glucose shifting from Fischer projection to Haworth projection.






圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/D-glucose-chain-2D-Fischer.png/67px-D-glucose-chain-2D-Fischer.png


The Fischer projection of the chain form of D-glucose



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/D-glucose-chain-2D-skeletal-numbers.png/120px-D-glucose-chain-2D-skeletal-numbers.png


The chain form of D-glucose



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Alpha-D-glucopyranose-2D-skeletal.png/120px-Alpha-D-glucopyranose-2D-skeletal.png


α-D-glucopyranose



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Beta-D-glucopyranose-2D-skeletal.png/120px-Beta-D-glucopyranose-2D-skeletal.png


β-D-glucopyranose






圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/D-glucose-chain-3D-balls.png/120px-D-glucose-chain-3D-balls.png


Chain form: ball-and-stick model



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/D-glucose-chain-3D-vdW.png/120px-D-glucose-chain-3D-vdW.png


Chain form: space-filling model



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/f/f3/Alpha-D-glucose-3D-sticks.png/120px-Alpha-D-glucose-3D-sticks.png


α-D-glucopyranose



圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/Beta-D-glucose-3D-sticks.png/120px-Beta-D-glucose-3D-sticks.png


β-D-glucopyranose