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TLS Online TPP Program

#Id: 854

Phytoplasmas are mainly spread by insects in the families Cicadellidae (leaf hoppers), Fulgoroidae (plant hoppers), and Psyllidae.

#Unit 2. Cellular Organization #Interrupted Genes #Part B Pointers
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TLS Online TPP Program

#Id: 7853

#Unit 1. Structure and Function of Biomolecules

Thus, D glucose in aqueous solution exists as an equilibrium mixture of 5 compounds. The pyranose form predominates in solution.

aD glucofuranose (0.5%)

aD-glucopyranose (37%)

aldehydo- -glucose (0.003%)

bD-glucofuranose (0.5%)

bD-glucopyranose (62%)
TLS Online TPP Program

#Id: 7854

#Unit 1. Structure and Function of Biomolecules

The optical activity of a stereoisomer is expressed quantitatively by its optical rotation.
The number of degrees by which plane-polarized light is rotated on passage through a given path length of a solution of the compound at a given concentration.
TLS Online TPP Program

#Id: 7855

#Unit 1. Structure and Function of Biomolecules

Optical rotation
TLS Online TPP Program

#Id: 7856

#Unit 1. Structure and Function of Biomolecules

When equal amounts of extrorotatory and levorotatory isomers are present, the resulting mixture becomes optically inactive because the optical activities of each isomer cancel each other.
Such a mixture is called a racemic or dl-mixture or (±)-conglomerate and this process of converting an optically active compound into the racemic modification is known of racemization. 
TLS Online TPP Program

#Id: 7857

#Unit 1. Structure and Function of Biomolecules

A freshly-prepared aqueous solution of α-D-glucose, has a specific rotation

A fresh solution of β-D-glucose, on the other hand, has a rotation value of +18.7°
TLS Online TPP Program

#Id: 7858

#Unit 1. Structure and Function of Biomolecules

All reducing sugars (except a few ketoses) undergo mutarotation