Hexose sugars are the ONLY building blocks for other polymers

[a_zed24]

Hello there,

my chem teacher said in class that ONLY hexose sugars, like glucose, can be repeated several times to produce oligo or polysaccharides. The other monosaccharides (triose, tetrose, pentose,...) can not do the same but are important for the formation of carbohydrates derivatives...is this correct? If yes, why? Why can't we have a polysaccharide whose building unit is a triose, for example?

Thanks in advance!

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[DagS132]

To be honest, never heard of that statement before. At the same time, I have never seen a polysaccharide of just pentoses either. Only thing off the top of my head is DNA/RNA, however those are nucleic acids.
Curious about the answer myself. Maybe something to do with steric hindrance. The other monosaccharides dont have that boat conformation.

 

[NextStepTutor_4]

Polysaccharides contain glycosidic bonds. In order for glycosidic bonds to be formed, a ring structure (usually a six-membered ring such as carbohydrate) would have to react with a hydroxyl group. It is unlikely to see a triose ring structure because of its instability and strain and therefore we would not see a triose polysaccharide.

Hope this helps!

 

[a_zed24]

Polysaccharides contain glycosidic bonds. In order for glycosidic bonds to be formed, a ring structure (usually a six-membered ring such as carbohydrate) would have to react with a hydroxyl group. It is unlikely to see a triose ring structure because of its instability and strain and therefore we would not see a triose polysaccharide.

Hope this helps!

Thank you, I understand now!

 

[a_zed24]

To be honest, never heard of that statement before. At the same time, I have never seen a polysaccharide of just pentoses either. Only thing off the top of my head is DNA/RNA, however those are nucleic acids.
Curious about the answer myself. Maybe something to do with steric hindrance. The other monosaccharides dont have that boat conformation.

Yeah, I've guessed that as well...thank you for your confirmation!