Carbohydrates Lecture Flashcards
How is the D-form recognised in a chain?
OH group on right side (dextro)
How is the D-form recognised in a ring?
Hydroxy methyl group in up position
How is the L-form recognised in a chain?
OH on left side
How is the L-form recognised in a ring?
Hydroxy methyl group in down position
How is the alpha form of a ring recognised?
OH group on carbon 1 in down position
How is the beta form recognised in a ring?
OH group on carbon 1 is in the up position
What determines whether a carbohydrate is D/L form?
Configuration of the chiral centre furthest from the carbonyl
What are the two types of monosaccharide?
Aldose and ketose
Is fructose an aldose or a ketose?
Ketose
How many carbon atoms are in a fructose ring?
Five
What is the general formula of carbohydrates?
(CH2O)n
What is another name for the monosaccharide Triose?
Glyceraldehyde
What is another name for the monosaccharide Tetrose?
Erythrose
Another name for monosaccharide hexose?
Glucose
Formula for sedoheptulose?
C7H14O7
Ribose (pentose) formula?
C5H10O5
When does optical isomerism occur?
When there is an asymmetric carbon atom (ie 4 different groups attached)
Name 4 glucose enantiomorphs
Glucose, mannose, galactose, fructose
Fischer projections - horizontal bonds joined to asymmetric carbon…
…are in front of the plane of the page
Fischer projections - vertical bonds joined to an asymmetric carbon…
…are behind the plane of the page
What type of bond is found in polysaccharide chains?
Alpha 1-4 bonds
What type of bond is found in branched polysaccharides?
Alpha 1-6 bonds
What two sugars make up lactose?
Beta-D-Galactose & Beta-D-Glucose
What type of bonding is present in lactose?
Beta 1-4 link
What enzyme is used to break down lactose?
Beta-D-galactosidase (lactase)
The disaccharide sucrose is a diner of which two sugars?
Glucose and fructose
What are uronic acids?
Monosaccharides with an ionisable COOH instead of CH2OH at carbon 6
What is ‘conjugation’ in terms of metabolism and excretion?
Addition of a uronic acid to a xenobiotic, increasing water solubility and providing labels recognised by excretion mechanisms
