Sorbitol Fischer Projection Quiz & Flashcards

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Questions and Answers

What type of ring does pyranose form?

Five-membered hemiacetal ring

Six-membered hemiacetal ring (correct)

Seven-membered hemiacetal ring

Four-membered hemiacetal ring

What is the characteristic of α anomer in a cyclic hemiacetal ring?

The -OH on the anomeric carbon is above the plane of the ring

The -OH on the anomeric carbon is on the side of the ring opposite from the terminal -CH2OH (correct)

The -OH on the anomeric carbon is on the same side of the ring as the terminal -CH2OH

The -OH on the anomeric carbon is below the plane of the ring

What type of ring is formed when aldehydes and ketones react with alcohols?

Six-membered cyclic hemiacetal

Four-membered cyclic hemiacetal

Five-membered cyclic hemiacetal (correct)

Seven-membered cyclic hemiacetal

What is the product called when the carbonyl group of a monosaccharide is reduced to an hydroxyl group?

Alditol Signup and view all the answers

What is the prefix 'deoxy' short for?

Without oxygen Signup and view all the answers

What is the process called when α- and β-anomers equilibrate in aqueous solution?

Mutarotation Signup and view all the answers

What is the approximate sweetness of sorbitol compared to sucrose?

60% as sweet as sucrose Signup and view all the answers

What is the name of the new carbon stereocenter created in forming the cyclic structure?

Anomeric carbon Signup and view all the answers

What is the product called when the aldehyde group of an aldose is oxidized under basic conditions?

Aldonic acid Signup and view all the answers

What is the orientation of the groups on carbons 1-5 of β-D-glucopyranose in Haworth projections and chair conformations?

Up, down, up, down, up Signup and view all the answers

What does the symbol 'β' indicate in carbohydrate chemistry?

The -OH on the anomeric carbon is on the same side of the ring as the terminal CH2OH Signup and view all the answers

What type of ring is D-glucose represented as in its most stable form?

Chair conformation ring Signup and view all the answers

What is the primary purpose of a Fischer projection?

To represent the configuration of tetrahedral stereocenters Signup and view all the answers

What is the general formula for a monosaccharide?

CnH2nOn Signup and view all the answers

What is the difference between an aldose and a ketose?

An aldose has an aldehyde group, while a ketose has a ketone group Signup and view all the answers

How are D-monosaccharides and L-monosaccharides differentiated?

By the position of the -OH on the penultimate carbon Signup and view all the answers

What is unique about the three amino sugars found in nature?

They all contain an -NH2 group in place of an -OH group Signup and view all the answers

What is the term for a monosaccharide that cannot be hydrolyzed to a simpler carbohydrate?

Monosaccharide Signup and view all the answers

What is the role of glucuronic acid in the body?

It is used to detoxify foreign phenols and alcohols Signup and view all the answers

What type of bond joins the two units of D-glucopyranose in maltose?

α-1,4-glycosidic bond Signup and view all the answers

What is the charge of a diphosphoric ester at the pH of cellular and intercellular fluids?

-2 Signup and view all the answers

What is the difference between amylose and amylopectin?

Amylose is composed of unbranched chains, while amylopectin is branched Signup and view all the answers

What is sucrose?

A type of disaccharide Signup and view all the answers

What is the difference between reducing and non-reducing sugars?

Reducing sugars have an aldehyde or ketone group, while non-reducing sugars do not Signup and view all the answers

What is a characteristic common to most connective tissues?

They contain collagen and acidic polysaccharides Signup and view all the answers

What is the function of hyaluronic acid in the vitreous of the eye?

It maintains the retina in its proper position Signup and view all the answers

Why can humans not use cellulose as a source of glucose?

Because our digestive systems lack β-glucosidases Signup and view all the answers

What is the molecular weight range of heparin?

6000-30,000 g/mol Signup and view all the answers

Where is heparin synthesized and stored?

In mast cells of various tissues Signup and view all the answers

What is the best understood biological function of heparin?

Its anticoagulant activity Signup and view all the answers

Study Notes

Carbohydrates and Their Structures

Anomeric Carbon: α formation means the -OH group is opposite to the terminal -CH2OH; β formation means it is on the same side.
Ring Structures: Pyranose indicates a six-membered hemiacetal ring, while furanose refers to a five-membered hemiacetal ring.
Aldopentoses: These also form cyclic hemiacetals due to their structure.

Mutarotation

Definition: Mutarotation is the change in specific rotation during the equilibration of α- and β-anomers in solution.
Example: Dissolving either α-D-glucose or β-D-glucose in water leads to a specific rotation equilibrium of +52.7°, with compositions of 64% β and 36% α forms.

Reduction to Alditols

Reduction Process: Monosaccharides can have their carbonyl group reduced to a hydroxyl group by agents like NaBH4 or H2 with a transition metal catalyst.
Alditols: Resulting from such reductions; common example: Sorbitol, found in fruits and used as a sugar substitute, is 60% as sweet as sucrose.

Oxidation of Aldoses

Aldonic Acids: The aldehyde group in aldoses can be oxidized to form carboxylate anions under basic conditions.

Cyclic Structures

Formation: Aldehydes and ketones react with alcohols to create hemiacetals, forming five- or six-membered rings.
D-Ribose: Predominantly occurs in the furanose form in nature.
D-Fructose: Forms a furanose cyclic structure as a 2-ketohexose.

Haworth Projections and Chair Conformations

Cyclic Hemiacetals Representation: D-Glucose forms cyclic hemiacetals depicted in Haworth projections.
Chair Conformations: Provides a more accurate representation of pyranose structures, showing ring orientations and substituent positions.

Anomers and Stereochemistry

Anomeric Carbon: C-1 for aldoses and C-2 for ketoses; stereoisomers differing at the anomeric carbon are termed anomers.
β-D-Glucopyranose: In its structure, the group orientations on carbons 1-5 are specified as up, down, up, down, and up.

Carbohydrate Terminology

Carbohydrate Definition: Comprises polyhydroxyaldehydes or polyhydroxyketones, or compounds yielding them upon hydrolysis.
Monosaccharides: Simplest carbohydrates not reducible to simpler forms, following the general formula ( C_n(H_2O)_n ).
Classification: Based on the carbonyl group type; aldoses contain aldehyde groups, ketoses contained ketone groups.

Amino Sugars

Characteristics: Contain an -NH2 group instead of -OH; include D-glucosamine, D-mannosamine, and D-galactosamine.
Biological Role: Amino sugars help detoxify compounds in the liver.

Disaccharides and Polysaccharides

Polysaccharides: Composed of many monosaccharide units linked by glycosidic bonds; starch is a notable polymer of D-glucose consisting of amylose and amylopectin.
Maltose: A disaccharide made of two D-glucopyranose units linked by α-1,4-glycosidic bonds, classified as a reducing sugar.

Connective Tissue and Hyaluronic Acid

Connective Tissue: Comprises various forms like cartilage and bone, primarily made of collagen and acidic polysaccharides, notably hyaluronic acid.
Hyaluronic Acid Functions: Abundant in embryonic tissues and synovial fluid, it maintains tissue elasticity and hydration.

Cellulose and Heparin

Cellulose Structure: Linear polymer with up to 3000 units of D-glucose linked by β-1,4-glycosidic bonds; indigestible by humans due to lack of specific enzymes.
Heparin: A variable polysaccharide with anticoagulant properties, synthesized in mast cells, and has molecular weight ranging from 6,000 to 30,000 g/mol.

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Description

Test your understanding of carbohydrate stereochemistry and Fischer projections, a 2D representation of tetrahedral stereocenters. Learn about monosaccharides and how to interpret horizontal and vertical bonds.

Carbohydrate Stereochemistry: Fischer Projection

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