Carbohydrates: Structure and Nomenclature

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following correctly describes the basic nomenclature of carbohydrates?

Carbohydrates are named by their structural complexity.

Carbohydrates are named by their energy capacities.

Carbohydrates are named by the number of carbon atoms plus -on.

Carbohydrates are named by the number of carbon atoms plus -ose. (correct)

What type of carbohydrate is characterized by having aldehyde functionality?

Dioses

Ketose

Triose

Aldose (correct)

Which statement best describes epimers?

Epimers differ at more than one chiral center.

Epimers are mirror images of each other.

Epimers are synonymous with aldohexoses.

Epimers are diastereomers differing at one chiral center. (correct)

Which of the following carbohydrates can be produced from CO2 and H2O during photosynthesis?

Cellulose Signup and view all the answers

What structural feature differentiates D-Mannose and D-Galactose from D-Glucose?

They vary at more than one chiral center. Signup and view all the answers

Which statement accurately describes the cyclization of monosaccharides?

Cyclization of monosaccharides results in both straight and ring structures. Signup and view all the answers

What do we call the carbohydrate with the molecular weight of approximately 90 g/mol?

Glyceraldehyde Signup and view all the answers

Which of the following carbohydrates is primarily used as an energy storage molecule?

Glycogen Signup and view all the answers

What is the role of hydrogen peroxide in the oxidation of organic molecules?

It oxidizes organic molecules into highly colored compounds. Signup and view all the answers

Which statement accurately describes the glycosidic bond in disaccharides?

It connects an anomeric carbon to a hydroxyl carbon. Signup and view all the answers

What type of disaccharide is formed when two glucose molecules join via a 1 → 4 bond?

Maltose Signup and view all the answers

Which characteristic defines a nonreducing disaccharide?

It is formed by linking two anomeric carbons. Signup and view all the answers

How is the concentration of colored compounds measured after oxidation by hydrogen peroxide?

Colorimetric methods Signup and view all the answers

Which type of bond is more stable, a glycosidic bond or a hemiacetal?

Glycosidic bond Signup and view all the answers

What is true about the anomeric carbon in a glycosidic bond formation?

It is nonreducing in the bond. Signup and view all the answers

What type of natural carbohydrate structure is commonly found in nature?

Polymers or polysaccharides Signup and view all the answers

What characteristic makes cellulose a difficult substrate for most animals to metabolize?

The fibrous structure and water insolubility Signup and view all the answers

Which microorganism secretes cellulase, allowing them to utilize wood as a glucose source?

Fungi Signup and view all the answers

Chitin is primarily found in which of the following?

Mushrooms and arthropod exoskeletons Signup and view all the answers

Which of the following statements about inulin is true?

Its main function is energy storage in roots. Signup and view all the answers

Which property of agar makes it useful in laboratory settings?

It forms gels for bacterial growth. Signup and view all the answers

Which polysaccharide is known for being nearly pure fibrous cellulose?

Cotton Signup and view all the answers

Which of the following correctly describes the structure of cellulose?

Linear and tough, with H-bonds between chains Signup and view all the answers

Which of the following organisms can utilize glucose derived from cellulose due to symbiotic relationships?

Ruminants and termites Signup and view all the answers

What distinguishes homopolysaccharides from heteropolysaccharides?

Homopolysaccharides are made of one monomer unit. Signup and view all the answers

Which type of linkage is primarily found in glycogen chains?

α(1→4) linkages Signup and view all the answers

What is the main function of starch in plants?

Storage of glucose Signup and view all the answers

What do dextrins primarily result from?

The partial hydrolysis of starch or glycogen. Signup and view all the answers

Which of the following correctly describes amylopectin?

It is a branched homopolysaccharide. Signup and view all the answers

What characteristic differentiates the reducing end from nonreducing ends in glycogen?

The reducing end can participate in oxidation reactions. Signup and view all the answers

Which is a key feature of cellulose structure?

It is composed of β(1→4) linked chains. Signup and view all the answers

How do polysaccharides differ from proteins in terms of molecular structure?

Polysaccharides do not have a defined molecular weight. Signup and view all the answers

What are the repeating disaccharide units in glycosaminoglycans?

N-acetyl-glucosamine or N-acetyl-galactosamine Signup and view all the answers

Which polysaccharide is known for its role in energy storage in plants?

Starch Signup and view all the answers

Heparan sulfate is distinct from heparin because it is:

Attached to proteins Signup and view all the answers

What functional role does heparin serve in the body?

Preventing blood clotting by activating antithrombin Signup and view all the answers

Which of the following best describes the charge characteristics of glycosaminoglycans?

Negatively charged due to sulfate esters and uronic acids Signup and view all the answers

What is the primary structural role of cellulose in plants?

Structural support and rigidity Signup and view all the answers

Which polysaccharide plays a critical role in providing strength to the exoskeletons of insects and crustaceans?

Chitin Signup and view all the answers

Which of the following roles is fulfilled by hyaluronan in vertebrates?

Viscosity and lubrication in joints Signup and view all the answers

Which characteristic distinguishes agarose from other polysaccharides listed?

It is a heteropolysaccharide derived from algae Signup and view all the answers

What is the significance of the meshwork formed by glycosaminoglycans in the extracellular matrix?

It supports connective tissues and joint lubrication Signup and view all the answers

Study Notes

Carbohydrates

Carbohydrates are produced from carbon dioxide and water through photosynthesis in plants.
Carbohydrates serve many functions: as a source of energy, energy storage, structural component, and cell signaling molecules.
Carbohydrates can covalently link to proteins and lipids.

Carbohydrate Nomenclature

The basic nomenclature is based on the number of carbon atoms in the carbohydrate followed by "-ose."
For example, a three-carbon carbohydrate is called a triose.
All carbohydrates initially have a carbonyl functional group.
Aldehydes are called aldoses, and ketones are called ketoses.

Monosaccharides

Monosaccharides can be constitutional isomers: aldose is a carbohydrate with aldehyde functionality, ketose is a carbohydrate with ketone functionality
Monosaccharides can be stereoisomers: epimers are stereoisomers differing at only one chiral center; epimers are not mirror images, therefore not enantiomers; epimers are diastereomers; diastereomers have different physical properties
Monosaccharides can have straight and ring structures.

Disaccharides and Glycosidic Bond

Two sugar molecules can be joined via a glycosidic bond between an anomeric carbon and a hydroxyl carbon.

Polysaccharides

Polysaccharides are typically found in their polymer forms.
Polysaccharides can be homopolysaccharides (one monomer unit), heteropolysaccharides (multiple monomer units), linear (one type of glycosidic bond), and branched (multiple types of glycosidic bonds).
Polysaccharides don't have a defined molecular weight.
Polysaccharides are often in a state of flux, with monomer units added and removed as needed by the organism.

Homopolymers of Glucose: Glycogen

Glycogen is a branched homopolysaccharide of glucose.
Glucose monomers form (α1 4) linked chains and branch points with (α1 6) linkers every 8–12 residues.
Glycogen functions as the main storage polysaccharide in animals.

Homopolymers of Glucose: Starch

Starch is a mixture of two glucose homopolysaccharides: amylose and amylopectin.
Amylose is unbranched with (α1 4) linked residues.
Amylopectin is branched like glycogen, but the (α1 6) linkers occur every 24–30 residues.
Starch is the main storage polysaccharide in plants.

Dextrins

Dextrins are low-molecular-weight carbohydrates produced by partial hydrolysis of starch or glycogen.
They are polymers or D-glucose linked by α-(1→4) or α-(1→6) glycosidic bonds.
Dextrins can be produced in the gut and during cooking.
Dextrins can be used as water-soluble adhesives.

Homopolymers of Glucose: Cellulose

Cellulose is a linear homopolysaccharide of glucose.
Glucose monomers form (1 4) linked chains.
Hydrogen bonds form between adjacent monomers and additional H-bonds between chains.
Cellulose is tough, water insoluble, and the most abundant polysaccharide in nature.
Cotton is nearly pure fibrous cellulose.

Chitin

Chitin is a linear homopolysaccharide of N-acetylglucosamine.
N-acetylglucosamine monomers form (1 4)-linked chains.
Chitin forms extended fibers similar to those of cellulose.
It is hard, insoluble, and cannot be digested by vertebrates.
Chitin is found in cell walls of mushrooms and exoskeletons of insects, spiders, crabs, and other arthropods.

Inulin

Inulin is a plant polysaccharide made from fructose units with a chain-terminating glucose.
Inulin has a sweet taste and is present in roots for energy storage.
Most plants that synthesize inulin do not store energy in the form of starch.
Inulin is a good source of dietary fiber.

Agar and Agarose

Agar is a branched heteropolysaccharide composed of agarose and agaropectin.
Agar is a cell wall component in some seaweeds.
Agar solutions form gels used in laboratories as a surface for growing bacteria.
Agarose solutions form gels used in laboratories for DNA separation via electrophoresis.

Glycosaminoglycans

Glycosaminoglycans are linear polymers of repeating disaccharide units.
One monomer is either N-acetyl-glucosamine or N-acetyl-galactosamine.
They are negatively charged due to uronic acids and sulfate esters.
Glycosaminoglycans form an extended hydrated molecule which minimizes charge repulsion.
They form a meshwork with fibrous proteins to form the extracellular matrix, connective tissue, and lubricate joints.

Heparin and Heparan Sulfate

Heparin is a linear polymer of 3–40 kDa.
Heparan sulfate is a heparin-like polysaccharide attached to proteins.
They have the highest negative-charge density among biomolecules.
Heparin prevents blood clotting by activating the protease inhibitor antithrombin.
Heparin regulates development and blood vessel formation by binding to various cells.
Heparin can bind to viruses and bacteria, decreasing their virulence.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the essential aspects of carbohydrates, including their production, functions, and nomenclature. It delves into monosaccharides, isomers, and their roles in biological systems. Test your understanding of these crucial biological molecules.