Lecture 19, Carbohydrates (Ford) Flashcards
In constitutional isomers, what changes?
Order of atoms
T or F: Constitutional isomers are tautomers.
True.
In a tautomer, where does carbon numbering start?
Carbonyl end of the aldose
Fisher projections are the ___ versions of carbohydrates.
Linear
Describe stereoisomers.
Same connectivity, different spatial organizations
What kind of carbons do configurational isomers have?
Chiral
Describe enantiomers.
Mirror images at all chiral centers
T or F: Diastereomers can have only 1 chiral center, as long as the images do not mirror one another.
False. Diastereomers must have multiple chiral centers.
Describe diastereomers.
Not mirror images overal
Hawthorne projections are the ___ versions of carbohydrates.
Cyclical
Outline how to convert a monosaccharide from a Fisher to a Hawthorne projection.
- Choose the ring
- Carbonyl C goes 1 position CW from the O
- Number C CW
- =O becomes OH
- Left side goes up, right side goes down
When converting from a Fisher to a Hawthorne projection, what do beta and alpha signify when the =O becomes an OH?
Beta = up Alpha = down
How do anomers differ?
At anomeric C only
How do epimers differ?
At any other C than the anomeric C
What kind of rotation changes do conformational isomers have?
Reversible rotation changes
List the monosaccharides to know.
Glyceraldehyde, ribose, glucose, galactose, dihydroxyacetone, ribulose, fructose, D-deoxyribose, D-mannose
When are glycosides formed?
When one or more hydroxyls are replaced
What can hydroxyls be replaced with to form a glycoside?
Fucose, esters (phosphorylation), oxidation/reduction (alcohols), N-linkages (amino sugars, nucleotides), O-linkages (methylation, toxins)
Why is fucose weird?
Galactose derivative; only L-monosaccharide made and used by mammals; part of A/B/O blood antigens
What can excess fucose in the blood lead to?
Liver damage, cancer, diabetes, heart disease
Describe how monosaccharides can be modified via phosphorylation.
Important reactive intermediates in carbohydrate metabolism, adds negative charge, phosphate from ATP
What is the relationship between a monosaccharide and a phosphate modification?
Name of monosaccharide tells you where to put the phosphate
What kind of linkages do phosphates have?
Ester
Where are reducing sugars oxidized in monosaccharides?
Carbonyl
What does the oxidation of a monosaccharide make?
Acids and lactones
What does the reduction of a monosaccharide make?
Alditols
What can cause cataracts if it accumulates in the lens of the eye?
Sorbitol (reduction of carbonyl)
Where are monosaccharides that are modified with amino sugars found?
In branched polysaccharides (like cell walls)
List the essential, regular monosaccharides.
D-glucose, D-galactose, D-mannose, D-xylose
Of the essential monosaccharides, which is the oddball?
L-fucose
Of the essential monosaccharides, which are amino sugars?
GlcNAc, GalNAc, sialic acid
List the essential monosaccharides.
D-glucose, D-galactose, D-mannose, D-xylose, L-fucose, GlcNAc, GalNAc, sialic acid
List the roles of polysaccharides.
Glucose storage, structure, protein diversity
Which structural polysaccharide is essentially universal?
Chitin
List how polysaccharides create protein diversity.
Glycoproteins, glycosaminoglycans, mucins
T or F: In glycoproteins, protein < sugar.
False. In glycoproteins, protein > sugar.
What are glycoproteins called on membrane and soluble proteins?
Membrane = cell adhesion Soluble = cell signaling
T or F: In glycosaminoglycans, sugar < protein.
False. In glycosaminoglycans, sugar > protein.
Describe the structure of glycosaminoglycans.
Repeating disaccharide units, sugar component of proteoglycans (cartilage, blood clotting, chitin)
In mucins, sugar ___ protein.
>
What do mucins provide?
Lubrication (protection, hydration)
How are glycolipids related to blood type?
Decorate cell membranes and are used to recognize self/other
