5. Carbohydrates Flashcards
What is an acetal?
a molecule containing two -OR or -OAr groups bonded to the same carbon atom
What is alditol?
the product formed when the C=O group of a monosaccharide is reduced to a CHOH group
What is an aldose?
a monosaccharide containing an aldehyde group
What is an amylopectin?
a highly branched polymer of D-glucose. Chains of D-glucose are joined by α-1,4’ -glycoside bonds and branches are created by α-1,6’ -glycoside bonds
What is an amylose?
is composed of continuous, unbranched chains of D-glucose units joined by α-1,4’ -glycoside bonds. It is water soluble
What is an anomer?
monosaccharides that differ in configuration only at their anomeric carbon atom
What is an anomeric carbon?
The hemiacetal carbon atom of the cyclic form of a monosaccharide
What is a carbohydrate?
polyhydroxyaldehydes, polyhydroxyketones or substances that give either of these compounds after hydrolysis
What is cellulose?
a linear polymer of D-glucose units joined by β-1,4’ -glycoside bonds
What is a chair conformation?
the most stable puckered conformation of a cyclohexane ring
What is a D-monosaccharide?
a monosaccharide that, when written as a Fischer projection has the -OH on its penultimate carbon atom to the right
What is a disaccharide?
any of a class of sugars whose molecules contain two monosaccharide residues
What is a Fischer projection?
two-dimensional representations that show the configuration of a stereocentre; horizontal lines represent bond projecting forward from the stereocentre, vertical lines represent bonds projecting to the rear
What is a furanose?
a five-membered cyclic hemiacetal form of a monosaccharide
What is glycogen?
the reserve carbohydrate for animals. Glycogen is a non-linear polymer of D-glucose unit joined by α-1,4’ -and α-1,6’ -glycoside bonds
What is a glycoside?
a carbohydrate in which the -OH on its anomeric carbon atom is replaced by -OR
What is a glycosidic bond?
the bond from the anomeric carbon atom of a glycoside to an -OR group
What is a Haworth projection?
a way of viewing furanose and pyranose forms of monosaccharides. The ring is drawn flat and viewed through its edge, with the anomeric carbon atom on the right and the oxygen atom of the ring at the rear to the right
What is a hemiacetal?
a molecule containing an -OH and an -OR or -OAr group bonded to the same carbon atom
What is invertase?
an enzyme that catalyses the hydrolysis of sucrose
What is a ketose?
monosaccharides containing a ketone group
What is a L-monosaccharide?
a monosaccharide that, when written as a Fischer projection, has the -OH on its penultimate carbon to the left
What is a monosaccharide?
carbohydrates that cannot be hydrolysed to simpler compounds
What is mutarotation?
the change in optical activity that occurs when an α or β form of a carbohydrate is converted to an equilibrium mixture of the two forms
What is an oligosaccharide?
carbohydrate containing 4 to 10 monosaccharide units joined by glycosidic bonds
What is a penultimate carbon?
the stereocentre of a monosaccharide furthest from the carbonyl group; for example, C(5) of glucose
What is a polysaccharide?
carbohydrates containing a large number of monosaccharide units joined together by one or more glycosidic bonds
What is a pyranose?
a six-membered cyclic hemiacetal form of a monosaccharide
What is a reducing sugar?
a carbohydrate that reacts with an oxidising agent to form an aldonic acid
What naming convention is used to identify enantiomers?
D,L convention
What is the open form of a sugar called?
Hemiacetal
What infix is used to denote a six-membered ring?
-pyran-
What infix is used to denote a five-membered ring?
-furan-
True or False: a beta anomer is trans
False - a beta anomer is cis, an alpha anomer is trans
True or False: Haworth projections can be used to represent five-membered rings
True - They are pretty close to planar
When the carbonyl group of a monsaccharide is reduced what product is formed?
Alditol
When the carbonyl group of a monsaccharide is oxidised what product is formed?
Aldonic acid
What type of bonds are glycogen subunits connect by?
α-1,4’ -and α-1,6’ (branch) -glycoside bonds
What type of bonds are cellulse subunits connected by?
β-1,4’ -glycoside bonds
