Biomolecules: Carbohydrates

What functional group is present in all carbohydrates?

hydroxl OH

What is the difference between monosaccharides - oligosaccharides - polysaccharides?

• mono is one sugar unit

• oligo is 2-100 sugar residues

• poly is 100- thousands sugar residues

What do sugars contain to prove optical isomerism exists?

chiral carbons

how do you designate the two enantiomers?

using an L or D prefix

What happens when alcohols react with aldehydes and ketones?

forms hemi acetyles or hemi ketals

what is an anoremic carbon?

when sugars are in the ring form and carbon 1 is chiral

what is an anomer

OH group at C-1 is on the opposite side of the ring from the CH₂OH group

what is a b anomer

OH group at C-1 is on the same side of the ring as the CH₂OH group

what anomer is preffered and why?

b is preffered as it minimises hinderance between OH group

what is glycosidic linkage?

when the cyclic form of one monosaccharide can react with an alcohol group to form a disaccharide

How do you break a glyosidic bond?

hydrolyse it with acid + heat or specific enzyme

what is maltose

a disaccharide formed by the linkage of two monosaccharides with the eliminationof water

how is maltose a reducing agent

as it can exist in open chain form so possess an aldehyde group - can exist in both a nd b anomeric forms in solution

why is sucrose non reducing

the rings of glucose and fructose are locked so the disaccaride does not osses a free aldehyde

polysaccarides function

insoluble and difficult to purify

what is glycogen

energy reserve polysaccaride abundant in the liver

how is glycogen broken down

enzymic reactions

what does celluloses linearity cause?

polymers to line up in fibres with hydrogen bonding