What is the difference between alpha and beta glycosidic bond?

"Glucose, C6H12O6 a monosaccharide (or simple sugar), is the most important carbohydrate in biology. Cell use it as a source of energy and is a metabolic intermediate. In addition glucose is one of the main products of photosynthesis and starts cellular respiration in both prokaryotes and eukaryotes.

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Glucose 3D Molecular Structures using Jsmol
What's the difference between glycosidic bonds?
How do you know if a linkage is alpha or beta?
Can glycosidic bonds be alpha or beta?
What is B glycosidic bond?

Two isomers of the aldohexose sugars are known as glucose,of which only one (D-glucose) is biologically active.The mirror-image of the D-glucose , L-glucose, cannot be used by cells. In solutions, the open-chain form of glucose (either 'D-' or 'L-') exists in equilibrium with several cyclic isomers, each containing a ring of carbons closed by one oxygen atom.

The D-glucose can exist in two forms alpha-D-glucose and beta-D-glucose. They differ only in the direction that -H and -OH groups point on carbon 1 (See the jmol images below). When alpha-glucose molecules are joined chemically to form a polymer starch is formed. When beta-glucose molecules are joined to form a polymer cellulose is formed.

Glucose 3D Molecular Structures using Jsmol

When a glucopyranose molecule is drawn in the Haworth projection, the designation 'a-' means that the hydroxyl group attached to C-1 and the -CH2OH group at C-5 lies on opposite sides of the ring's plane (a trans arrangement), while 'ß-' means that they are on the same side of the plane (a cis arrangement). See below.

Haworth projection of a--D- Glucopyranose

Haworth projection of ß-D- Glucopyranose

-------------->&lt;a&gt;spin on&lt;/a&gt; --------&amp;gt;- &lt;a&gt;spin off&lt;/a&gt;&lt;br /&gt; ------&lt;a&gt;&amp;gt;space fill/cpk&lt;/a&gt; --------&amp;gt;&lt;a&gt;stick&lt;/a&gt; ----&amp;gt;&lt;a&gt; ball-and-stick&lt;/a&gt;&lt;br /&gt; &lt;/div&gt; &lt;div class="col-md-6 col-sm-6"&gt; &lt;br /&gt; &lt;script type="text/javascript"&gt; jmolApplet1 = Jmol.getApplet("jmolApplet1",Info1); Jmol.script(jmolApplet1,"background black;load beta_D_glucose.mol; spin on;") --------------&gt;&lt;a&gt;spin on&lt;/a&gt; --------&amp;gt;- &lt;a&gt;spin off&lt;/a&gt;&lt;br /&gt; ------&lt;a&gt;&amp;gt;space fill/cpk&lt;/a&gt; --------&amp;gt;&lt;a&gt;stick&lt;/a&gt; ----&amp;gt;&lt;a&gt; ball-and-stick&lt;/a&gt;&lt;br /&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;p&gt;&nbsp;&lt;/p&gt; &lt;p&gt;&nbsp;&lt;/p&gt; &lt;p&gt;What's the difference between starch and cellulose?&nbsp; &lt;/p&gt; &lt;p&gt;When alpha-glucose molecules are joined chemically to form a polymer starch is formed. When beta-glucose molecules are joined to form a polymer cellulose is formed.&lt;/p&gt; &lt;table width="88%" border="0" cellspacing="0"&gt; &lt;tbody&gt; &lt;tr&gt; &lt;td colspan="2" valign="top" height="125"&gt;&lt;p align="center"&gt;&lt;img src="http://www.edinformatics.com/interactive_molecules/Amylose.jpg" alt="1" width="270" /&gt;&lt;/p&gt;&lt;/td&gt; &lt;td width="8" height="125"&gt;&nbsp;&lt;/td&gt; &lt;td width="304" colspan="2" valign="top" height="125"&gt;&lt;p&gt;&lt;img src="http://www.edinformatics.com/interactive_molecules/Cellulose.jpg" alt="1" width="260" /&gt;&lt;/p&gt;&lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td colspan="2" height="37" valign="top"&gt;&lt;p&gt;&lt;u&gt;Starch&lt;/u&gt;: Alpha glucose is the monomer unit in&nbsp;&lt;br /&gt; starch.&nbsp;&lt;/p&gt; &lt;p&gt;As a result of the bond angles in the alpha acetal linkage, starch (amylose) actually forms a spiral structure.&lt;/p&gt;&lt;/td&gt; &lt;td width="8" height="37"&gt;&nbsp;&lt;/td&gt; &lt;td width="304" colspan="2" height="37" valign="top"&gt;&lt;p&gt;&lt;u&gt;Cellulose&lt;/u&gt;: Beta glucose is the monomer unit in cellulose.&nbsp;&lt;/p&gt; &lt;p&gt;As a result of the bond angles in the beta acetal linkage, cellulose is mostly a&nbsp;&lt;br /&gt; linear chain.&lt;/p&gt;&lt;/td&gt; &lt;/tr&gt; &lt;/tbody&gt; &lt;/table&gt; &lt;p&gt;&nbsp;&lt;/p&gt; &lt;div class="container-fluid"&gt; &lt;div class="row"&gt; &lt;div class="col-md-6 col-sm-6"&gt; &lt;script type="text/javascript"&gt; jmolApplet0 = Jmol.getApplet("jmolApplet2",Info2); Jmol.script(jmolApplet2,"background black;load dextrin_molecule.mol; spin on;") --------------&gt;&lt;a&gt;spin on&lt;/a&gt; --------&amp;gt;- &lt;a&gt;spin off&lt;/a&gt;&lt;br /&gt; ------&lt;a&gt;&amp;gt;space fill/cpk&lt;/a&gt; --------&amp;gt;&lt;a&gt;stick&lt;/a&gt; ----&amp;gt;&lt;a&gt; ball-and-stick&lt;/a&gt;&lt;br /&gt; &lt;br /&gt; &lt;br /&gt; &lt;hr /&gt; &lt;/div&gt; &lt;div class="col-md-6 col-sm-6"&gt; &lt;br /&gt; &lt;script type="text/javascript"&gt; jmolApplet3 = Jmol.getApplet("jmolApplet3",Info3); Jmol.script(jmolApplet3,"background black;load cellulose.pdb; spin on;") <br> --------------&gt;<a>spin on</a> --------&gt;- <a>spin off</a><br> ------<a>&gt;space fill/cpk</a> --------&gt;<a>stick</a> ----&gt;<a> ball-and-stick</a><br> </div> </div> </div> <p>&nbsp;</p> <p>&nbsp;</p> <p>&nbsp;</p> <div align="center"> <p align="left">Humans are unable to digest cellulose because the enzymes to breakdown the beta acetal linkages are not found in vertebrates. 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World of Molecules

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3D Structures using Jsmol/Jmol
Explain it with Molecules
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Acid and Base Molecules

What's the difference between glycosidic bonds?

The main difference between glycosidic bond and peptide bond is that a glycosidic bond is formed when two carbon atoms of two different monosaccharides are linked together whereas a peptide bond is formed when a carbon atom of one amino acid is linked to a nitrogen atom of a different amino acid.

How do you know if a linkage is alpha or beta?

Alpha linkage has the oxygen (on the aldehyde or ketone) below the ring and the beta has it above the ring. Down the page, it shows beta-Maltose. The label beta (for the right most oxygen) is unimportant since the link has to be alpha for it to be maltose. A beta link would result in a molecule of cellobiose.

Can glycosidic bonds be alpha or beta?

Note that the glycosidic bond can be alpha or beta, and that the second carbohydrate can be linked at any of the carbon atoms that contain an -OH. The glycosidic bond is named as alpha or beta, followed by numbers that correspond to the locations of the carbons involved in the glycosidic bond.

What is B glycosidic bond?

Glycosidic bond. A covalent bond that joins the hemiacetal group of a saccharide molecule and the hydroxyl group of some organic compound (e.g., an alcohol). Chemical reaction between an amino acid and a reducing sugar, which is important in the food industry as a form of non-enzymatic browning.