IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

ashgirl

can some1 tell me gud pts of difference b/w

1. alpha-D glucose and beta -D- glucose

2. alpha helix and beta pleated

p.s frm biomolecules

ashgirl

i'm really sorry if i have not mentioned. but IT IS VERY VERY IMPORTANT!!!!

Radon222

When glucose forms a ring (think Haworth conformation), carbon one can have its hydroxyl group in one of two conformations: axial (pointing straight down) or equatorial (pointing slightly up). When it is axial, the glucose is alpha. When it is equatorial, it is beta. This doesn't have as much impact on free, monomeric glucose because it can switch back and forth rapidly (though beta is preferred because it is more stable).

When glucose is polymerized into polysaccharides, though, it matters a lot. If alpha glucose is polymerized you get starch, which is soluble and digestible by humans. If you polymerize beta glucose, however, you get tough, undigestable cellulose.

sandeepramesh

for all these refer the ncert text book

varshavallig

alpha helix:here the strands of polypeptide twist over one another
intra H- bonding is present.
beta:here the strands are stretched to max. extent and placed side by side.
inter H- bonding is present.
H-bond point is vey imp,often asked
hope this helps
!!!!!!!!!!!!!

eistien

alpha D glucose and B D glucose are anomers which differ in config at C1 carbon and they have sligthly diff melting points and their reactivity is sligthly diff but otherwise they show similar properties

helix and pleath strutctures are those of the secondary structure of proteins and while helical structures consists of double stranded linked polpeptide chains pleathed structure depicts the plane shape of polypeptide linkages in 2D while helical is # dimensional!!!

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