Structural Carbohydrates - Biochemistry
Card 0 of 6
Which of the following statements about carbohydrates is true?
Which of the following statements about carbohydrates is true?
Glucose has five (not six) hydroxyl groups. Reducing sugars either have an aldehyde group or can form one through isomerism; sucrose doesn’t fit either description. Although there are more amylose molecules than amylopectin in starch, amylose is a minor component by mass; amylopectin makes up 70-80% of starch by mass. Polysaccharides are indeed joined in the union of two oses, which form glycosidic bonds.
Glucose has five (not six) hydroxyl groups. Reducing sugars either have an aldehyde group or can form one through isomerism; sucrose doesn’t fit either description. Although there are more amylose molecules than amylopectin in starch, amylose is a minor component by mass; amylopectin makes up 70-80% of starch by mass. Polysaccharides are indeed joined in the union of two oses, which form glycosidic bonds.
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What functional groups are present on carbohydrates?
What functional groups are present on carbohydrates?
Carbohydrate chains contain aldehyde or ketone functional groups, which are types of carboxyl groups. Remember the general formula for a carbohydrate is: 
since they are hydrates (water) of carbon.
Carbohydrate chains contain aldehyde or ketone functional groups, which are types of carboxyl groups. Remember the general formula for a carbohydrate is:
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Which of the following is not an example of a compound that contains carbohydrate in its structure?
Which of the following is not an example of a compound that contains carbohydrate in its structure?
To identify the answer choice that is NOT a polysaccharide, let's go delve into each answer choice a bit.
Cellulose is a polysaccharide and also a very important component of the cell wall of plants. It consists of many glucose sugars bound together via beta (1-4) linkages.
Peptidoglycan is also a polysaccharide and a very important component of the cell wall of bacteria. Its structure consists of alternating N-acetylglucosamine and N-acetylmuramic acid connected via beta (1-4) linkages. Both of these are modified sugar molecules.
Chitin is a polysaccharide that plays an important role in the structure of the exoskeleton of many fungi, arthropods, and insects. Its structure consists of a long chain of N-acetylglucosamine, which is a derivative of the sugar glucose.
Collagen is the only answer choice that does not represent a carbohydrate. Rather, collagen is a protein that plays a very important role in the extracellular matrix of various connective tissues found in animals.
Glycogen is a branched form of glucose that is the storage form in animals. It contains beta (1-4) and beta (1-6) linkages.
To identify the answer choice that is NOT a polysaccharide, let's go delve into each answer choice a bit.
Cellulose is a polysaccharide and also a very important component of the cell wall of plants. It consists of many glucose sugars bound together via beta (1-4) linkages.
Peptidoglycan is also a polysaccharide and a very important component of the cell wall of bacteria. Its structure consists of alternating N-acetylglucosamine and N-acetylmuramic acid connected via beta (1-4) linkages. Both of these are modified sugar molecules.
Chitin is a polysaccharide that plays an important role in the structure of the exoskeleton of many fungi, arthropods, and insects. Its structure consists of a long chain of N-acetylglucosamine, which is a derivative of the sugar glucose.
Collagen is the only answer choice that does not represent a carbohydrate. Rather, collagen is a protein that plays a very important role in the extracellular matrix of various connective tissues found in animals.
Glycogen is a branched form of glucose that is the storage form in animals. It contains beta (1-4) and beta (1-6) linkages.
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Both cellulose and starch are polymers of glucose; why can't and enzyme that breaks down starch also break down cellulose?
Both cellulose and starch are polymers of glucose; why can't and enzyme that breaks down starch also break down cellulose?
Cyclized monosaccharides can exist in two different stereoisomers that depend on the orientation of the hydroxyl group on the anomeric carbon. If this 
group is on the opposite side of the ring as the 
group, the sugar as the alpha anomer. The opposite orientation is referred to at the beta anomer. Cellulose is a polymer of beta glucose while starch is a polymer of alpha glucose, and the bonds between these glucose monomers differ depending on their anomer. This makes it so an enzyme can recognize one or the other but not both. Note that D-sugars are biologically relevant.
Cyclized monosaccharides can exist in two different stereoisomers that depend on the orientation of the hydroxyl group on the anomeric carbon. If this
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Which of the following is true of the two forms of starch: amylose and amylopectin?
Which of the following is true of the two forms of starch: amylose and amylopectin?
Amylose and amylopectin are the two components of starch. Approximately 80% of starch is composed of amylopectin. Both amylose and amylopectin are comprised of glucose units, and both have only D-glucose units. Amylose differs from amylopectin in that amylose is a single unbranched chain, but amylopectin branches. Therefore, amylopectin has both alpha 1,4 glycosidic linkages as well as alpha 1,6 glycosidic linkages.
Amylose and amylopectin are the two components of starch. Approximately 80% of starch is composed of amylopectin. Both amylose and amylopectin are comprised of glucose units, and both have only D-glucose units. Amylose differs from amylopectin in that amylose is a single unbranched chain, but amylopectin branches. Therefore, amylopectin has both alpha 1,4 glycosidic linkages as well as alpha 1,6 glycosidic linkages.
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Which of the following is not a glycosaminoglycan?
Which of the following is not a glycosaminoglycan?
A glycosaminoglycan (GAG) is a long, unbranched polysaccharide that consists of many repeating disaccharide units. Dermatan sulfate, keratan sulfate, hyaluronate, and heparin are all examples of glycosaminoglycans. Erythropoietin, however, is a glycoprotein hormone that stimulates production of red blood cells.
A glycosaminoglycan (GAG) is a long, unbranched polysaccharide that consists of many repeating disaccharide units. Dermatan sulfate, keratan sulfate, hyaluronate, and heparin are all examples of glycosaminoglycans. Erythropoietin, however, is a glycoprotein hormone that stimulates production of red blood cells.
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