Week 5 (Carbohydrate Monomers) Flashcards
Why are carbohydrates important?
- distributed widely in nature
- key intermediates of metabolism (sugars)
- prove a huge range of cellular markers:
Polysaccharides are centrally involved in cell-cell recognition (how one type of cell distinguishes itself from another)
Small polysaccharide chains, covalently bound by glycosidic links to hydroxyl groups on proteins (glycoproteins) act as biochemical markers on cell surfaces, determining things such as blood type
What is an oligosaccharide?
What is a polysaccharides?
They are made up of several units
They are made up of many units
What is an Aldose?
Contains an aldehyde
What is a ketose?
A carbohydrate containing a ketone
What is a chiral centre?
A carbon atom with 4 different groups attached
What are the root names of sugars with varying numbers of carbon atoms?
3 carbons= triose
4 carbons= tetrose
5 carbons= pentouse
6 carbons= hexose
7 carbons= heptose
What are enantiomers?
Mirror images
Transposing any 2 of the groups on a chiral carbon results in a different compound with different physical properties: How do you work out the number of isomers?
2n Where n=the number of asymmetric carbons
What does ‘D’ (dextrorotatory) mean?
The plane has been rotated to the right
Do enantiomers have identical physical properties (e.g boiling point)?
Yes
What are epimers?
Sugars differing at a single asymmetric centre
What are enantiomers?
Sugars differing at all of their asymmetric (chiral) centres are mirror images
What are diasterioisomers?
Sugars differing at one or more chiral centre and which are not enantiomers (mirror images)
Do Diasterioisomers have the same physical properties?
No
What does an aldehyde and a alcohol react to produce?
A hemiacetal (There is an equilibrium set up)
What does a ketone and an alcohol react to produce?
A hemiketal (There is an equilibrium set up)
What is the 5 membered ring called?
Furan (Furanses)
Why are most sugars optically active?
They can rotate the plane of a beam of polarised light
What does ‘L’ (Levorotatary) mean?
The plane has been rotated to the left