Sugars/Polysaccharides (Serwer 1) Flashcards by Dakota Miller

Describe carbohydrates as metabolic intermediates

-Energy storage (glycogen in animals, starch in plants) -Energy transformation (glucose): Production of acid and metabolic intermediates (ATP)

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Describe carbohydrates as components of genetic information-carrying molecules

Ribose and Deoxyribose: Components of RNA and DNA, respectively

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Describe carbohydrates as components of connective tissues and biofilms

Skin, cartilage, and teeth: Hyaluronic acid, chondroitin sulfates, heparin, heparin sulfates, and keratin sulfate

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Describe carbohydrates as cell membrane components

Covalent attachment to membrane-bound proteins and lipids where they signal cell migration and are virus attachment sites

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Describe carbohydrates as dental impressions

Alginates: formation of tough gels quickly and predictably

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Define simple carbohydrates

Straight-chained polyhydroxylated aldehydes or ketones, typically three, four, five, or six carbons in length (ex. trioses, tetraoses, pentoses, hexoses)

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Aldehydic carbohydrates are designated _____, whereas ketonic carbohydrates are designated ______.

-Aldoses -Ketoses

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The inversion of one or two asymmetric carbon atoms generates a completely new compound, which are called _______ of each other.

Diastereomers

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Define Structural Isomers

Alternative arrangement by which constituent atoms are covalently bonded

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Define Optical Isomers

Isomers that have identical bonding pattern, but which rotate plane polarized light in different directions

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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

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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

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Epimer

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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

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Cyclic forms are called _____.

Anomers

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Cyclic forms are called _____.

Anomers

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Aldoses form _____ anomers, while ketoses form _____ anomers.

-Pyran -Furan

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In OH group in alpha anomers points _____, but in beta anomers points ______.

-Down (opposite direction of C6) -Up

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_____ 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

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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

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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.

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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)

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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

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The enzyme, lactase, cleaves lactose to ______ and ______.

Galactose and glucose

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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