Chapter 5 Homework

You isolate an organic molecule that contains C, H, O, N, and S. This molecule _____.

could be a glycoprotein

Which of the following is NOT a polymer?

glucose

What holds cellulose molecules together in bundles large enough to form fibers?

hydrogen bonds

The _____ functional group can always be found in a carbohydrate molecule.

hydroxyl

All of the following are polysaccharides EXCEPT _____.

lactose

Which of the following molecules contains at least one peptide bond?

peptidoglycan

Which of the following can vary among monosaccharides?

the number of carbon atoms

What is the difference between an aldose sugar and a ketose sugar?

the position of the carbonyl group

Which of the following do starch and cellulose have in common?

the size of their monosaccharide subunits

Select the statement that is incorrect.

All carbohydrates have the general formula Cn(H2O)nCn(H2O)n.

What type of bond is formed between two sugars in a disaccharide?

Glycosidic linkage

This is a ring model of a carbohydrate. Based on what you know about carbohydrate structure, suggest which atom(s) should be added to this model to complete it.

O

This is a linear model of a carbohydrate. Based on what you know about carbohydrate structure, suggest which atom(s) should be added to the model to complete it.

OH

Cellulose is _____.

a major structural component of plant cell walls

A sugar that has the chemical formula C5H10O5 would be characterized as _____.

a pentose

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

as a disaccharide

Based on what you know about the standard numbering system for carbons in carbohydrates, which carbon is highlighted in the model?

carbon 4

Which of the following polymers contain nitrogen?

chitin

Which polysaccharide is an important component in the structure of many animals and fungi?

chitin

Complete the following sentences about carbohydrates. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.

1. A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a (carbohydrate). 2. A carbohydrate that yields many monosaccharides when hydrolyzed is a (polysaccharide). 3. A (monosaccharide) cannot be hydrolyzed any further. 4. Lactose, the sugar in milk, is a (disaccharide), because it can be split into two monosaccharides.

What are three ways monosaccharides differ from one another?

1. The location of their carbonyl group 2. The number of carbon atoms they contain 3. The orientations of their hydroxyl groups

Which of the following classes of macromolecules always contains a carbohydrate portion?

Nucleic acids

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical?

The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific.

Which of the following can be used to distinguish monosaccharides from one another?

The number of carbon atoms they contain and the orientations of their hydroxyl groups

How do the α and β forms of glucose differ?

Their ring structures differ in the location of a hydroxyl group.

Which of the differences listed here could be found among molecules of the same monosaccharide?

There is a difference in the orientation of a hydroxyl group in the ring form.

A molecule with the chemical formula C6H12O6 is probably a _____.

monosaccharide

What type of linkage occurs between the two monomers in this model of lactose?

β-1,4-glycosidic linkage