Sugars/Polysaccharides (Serwer 1) Flashcards
Describe carbohydrates as metabolic intermediates
-Energy storage (glycogen in animals, starch in plants) -Energy transformation (glucose): Production of acid and metabolic intermediates (ATP)
Describe carbohydrates as components of genetic information-carrying molecules
Ribose and Deoxyribose: Components of RNA and DNA, respectively
Describe carbohydrates as components of connective tissues and biofilms
Skin, cartilage, and teeth: Hyaluronic acid, chondroitin sulfates, heparin, heparin sulfates, and keratin sulfate
Describe carbohydrates as cell membrane components
Covalent attachment to membrane-bound proteins and lipids where they signal cell migration and are virus attachment sites
Describe carbohydrates as dental impressions
Alginates: formation of tough gels quickly and predictably
Define simple carbohydrates
Straight-chained polyhydroxylated aldehydes or ketones, typically three, four, five, or six carbons in length (ex. trioses, tetraoses, pentoses, hexoses)
Aldehydic carbohydrates are designated _____, whereas ketonic carbohydrates are designated ______.
-Aldoses -Ketoses
The inversion of one or two asymmetric carbon atoms generates a completely new compound, which are called _______ of each other.
Diastereomers
Define Structural Isomers
Alternative arrangement by which constituent atoms are covalently bonded
Define Optical Isomers
Isomers that have identical bonding pattern, but which rotate plane polarized light in different directions
A mixture of equal amounts of optical isomers is called _____ and will not rotate the plane of polarized light. _______ have mirror inversions at some, not all, chiral carbons. Optical isomers and diastereomers and both in the class of ________.
-Racemic -Diastereomers -Stereoisomers
D- and L- enantiomers of a carbohydrate with more than one chiral center are given the same name. Diastereomers are given different names. A diastereomer is also called an _____ when only one chiral center differentiates two sugars.
Epimer
D- and L- enantiomers of a carbohydrate with more than one chiral center are given the same name. Diastereomers are given different names. A diastereomer is also called an _____ when only one chiral center differentiates two sugars.
Epimer
How to identify D and L
- Starting at the end nearest the aldehydic or ketonic carbonyl carbon, number and identify the chiral carbon of highest number 2. Compare the chirality of this carbon to that of D and L glyceraldehyde
Cyclic forms are called _____.
Anomers
Cyclic forms are called _____.
Anomers
Aldoses form _____ anomers, while ketoses form _____ anomers.
-Pyran -Furan
In OH group in alpha anomers points _____, but in beta anomers points ______.
-Down (opposite direction of C6) -Up
_____ is the C3 epimer of galactose and is rare. But, a derivative of gulose is a component of the compound used for dental impressions. This compound is _____, obtained from brown algae.
-Gulose -Alginate
Reduction-oxidation (or redox) reactions are those in which there is a net transfer of electrons from one species to another: -_____ is the species that gives up electrons -_____ is the species that takes up elections
-Reductant -Oxidant
When is a sugar reducing?
The presence, or absence, of a free anomeric hydroxyl group in a cyclized carbohydrate determines whether it is a reducing sugar or not.
A bond formed between two simple carbohydrates is called a ________; linkage is a or B depending on the position of the anomeric hydroxyl involved in the formation of the linkage.
Glycosidic bond (or glycosidic linkage)
The names of di- and polysaccharides are based on their _____ and the type of ______. The a or B in the name is based only on the configuration of the “free” anomeric hydroxyl.
-Monomers -Glycosidic linkage
The enzyme, lactase, cleaves lactose to ______ and ______.
Galactose and glucose
Do all sugars have a reducing end?
No. Sucrose does not.
Sucrose is _____ (no OHs at anomeric carbons).
Non-reducing
Sucrose is cleaved by the enzymes ____ (intestine), _______ (stomach), and _______ (bacteria).
-Sucrase -Glycoside hydrolase -Invertase
Sucrose is the sugar that some bacteria, such as _____ and _____, use to make ______ (with dextransucrase).
-Streptococcus mutans and Streptococcus sobrinus -Dextran n sucrose –> (glucose)n + n fructose
Sucrose used to be most often used as a sweetener. High fructose corn syrup (______ + ______) is now often substituted.
Fructose + Glucose
Sucrose is converted to caramel (color of colas) by heating at _____ degrees C.
170
Sucrose is obtained from _____ and _____.
Cane and beets
Sucrose is obtained from _____ and _____.
Cane and beets
Bacteria coat surface of teeth and secrete polymers to form a film called a biofilm. The oral cavity has 200-300 species of bacteria. The bacterium that starts a “tooth decay” biofilm is usually ________, which produces lactic acid from glucose after splitting sucrose with invertase. It lives in an _____ environment better than most other oral bacteria (acidoduric).
-Streptococcus mutans -Acidic
One key polymer secreted is ______ (-1-6-linked D-glucose with mostly -1,4 but some -1,3 branches). n sucrose → (glucose)n + n fructose (enzyme = dextransucrase, works only on sucrose).
Dextran
Define, give examples, and state the function of Starches.
-a-linked polymers of glucose with n ~200 -Amylose and Amylopectin -Function: metabolic glucose storage in plants
Define Amylose
Linear polymer of a-1,4-linked D-glucose
Define Amylopectin
Polymer of α-1,4-linked D-glucose with α-1,6-branches (about 1 branch for every 30 a-1,4 linkages).
The enzyme in saliva that splits starch to maltose is ______.
Ptyalin (salivary amylase)
Define Cellulose.
Cellulose: Linear polymer of β-1,4-linked D-glucose (n > 3000). Not soluble in water; forms structurally stable fibrils.
Define Glycogen.
Polymer of α-1,4-linked D-glucose with α-1,6 branches. It functions as a metabolic glucose storage polymer in animals (esp. abundant in liver and skeletal muscle).
Branching density of glycogen is about ____ time ____ than amylopectin.
Three times higher
Extensive branching causes the glycogen molecule to become more compact, increasing _____.
Solubility
A glycogen molecule has many _______, but only one _______. Metabolically, this enables rapid mobilization of free glucose because glycogen phosphorylase, the enzyme that degrades glycogen, works at the non-reducing ends.
-Non-reducing ends -Reducing end
Heparin varies in both sulfation and sugar. The position of the glucuronate is sometimes occupied by ______. Heparin sulfate is similar to heparin, but has fewer sulfates and more _______.
-Iduronate -N-acetyl groups
Heparin binds to the protein, _______, and activates it, which then inactivates proteins needed for clotting: ________.
-Anti-thrombin III -Thrombin, factor Xa.
Heparin binds to the protein, _______, and activates it, which then inactivates proteins needed for clotting: ________.
-Anti-thrombin III -Thrombin, factor Xa.
Alginate, silicones and agar are among the materials used for dental impressions. Alginate is a ________. Linear chains of alginate are cross-linked by divalent cations, calcium, for example. This cross-linking causes the formation of a gel.
Linear block copolymer of -1,4-linked-D-mannuronate and -1,4-linked L-guluronate.
Control of calcium cation concentration is used to control gelation. This can be done by including _____ .
Phosphate
Optical isomers ____ and ____. [a] are different compounds; rotate plane polarized light in different directions [b] are the same compound; rotate plane polarized light in different directions [c] are the same compound; never rotate plane polarized light [d] are different compounds; never rotate plane polarized light
[b] are the same compound; rotate plane polarized light in different directions
The presence of an OH group at the ______ carbon(s) of a 6-carbon aldose sugar determines whether or not it is a reducing sugar. -1 -2 -3 -1, 2 -1, 6 -2, 3
-1
Anomers are generated by ______. [a] addition of an OH group [b] oxidation [c] reduction [d] cyclization [e] optical rotation
D. Cyclization
Sucrose is a ____, ___ sugar. -monomeric, reducing -dimeric, reducing -trimeric, reducing -monomeric, non-reducing -dimeric, non-reducing
-Dimeric, non-reducing
____ acts as an anti-blood clotting agent. -Glycogen -Dextran -Cellulose -Hyaluronic acid -Heparin
-Heparin
Example of aldose
Glucose
Example of ketose
Fructose
D-erythrose
(tetraaldose)
D-ribose
(pentaaldose)
D-glucose
(hexoaldose)
D-mannose
(hexoaldose)
D-fructose
(hexoketose)
B-D-glucopyranose
B-D-galactopyranose
a-D-mannopyranose
B-D-fructofuranose
B-D-ribofuranose
2-deoxy-B-D-ribofuranose
a-D-gulopyranose (gulose)
a-Lactose
Sucrose
Glucuronic Acid
Hyaluronic Acid
Chondroitin sulfates
