Other Macromolecules

Help Questions

GRE › Other Macromolecules

Questions 1 - 10
1

Fatty acids can vary in length. Which of the following fatty acids chains cannot not be synthesized in the human body?

A nineteen-carbon fatty acid chain

A twelve-carbon fatty acid chain

An eighteen-carbon fatty acid chain

A twenty-four-carbon fatty acid chain

A fourteen-carbon fatty acid chain

Explanation

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

2

Fatty acids can vary in length. Which of the following fatty acids chains cannot not be synthesized in the human body?

A nineteen-carbon fatty acid chain

A twelve-carbon fatty acid chain

An eighteen-carbon fatty acid chain

A twenty-four-carbon fatty acid chain

A fourteen-carbon fatty acid chain

Explanation

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

3

What is the difference between the alpha and beta forms of a monosaccharide?

The orientation of the hydroxyl group on the anomeric carbon

The number of carbons in the ring

The direction all hydroxyl groups point in the ring

Whether the monosaccharide is an aldose or a ketose

Explanation

When a monosaccharide becomes cyclic in form, the anomeric carbon can have its hydroxyl group pointing in the same direction as the methoxy group, or oriented in the opposite direction. This orientation determines whether the sugar is considered alpha or beta.

4

What is the difference between the alpha and beta forms of a monosaccharide?

The orientation of the hydroxyl group on the anomeric carbon

The number of carbons in the ring

The direction all hydroxyl groups point in the ring

Whether the monosaccharide is an aldose or a ketose

Explanation

When a monosaccharide becomes cyclic in form, the anomeric carbon can have its hydroxyl group pointing in the same direction as the methoxy group, or oriented in the opposite direction. This orientation determines whether the sugar is considered alpha or beta.

5

Two monosaccharides can be linked together to form a disaccharide. This linkage is known as a                      bond.

Glycosidic

Peptide

Phosphodiester

Hydrogen bond

Ionic

Explanation

Carbohydrates are linked together to form disaccharides and other polysaccharides through glycosidic linkages. A glycosidic linkage is one in where two sugar molecules are bridged by an oxygen atom. Peptide linkages are found between amino acids and phosphodiester bonds are found between nucleic acid monomers. Ionic bonds involve the complete transfer of one or more electrons from one species to another. Hydrogen bonds are weak intermolecular and intramolecular forces that contribute to the stability of many substances such as liquid water.

6

Two monosaccharides can be linked together to form a disaccharide. This linkage is known as a                      bond.

Glycosidic

Peptide

Phosphodiester

Hydrogen bond

Ionic

Explanation

Carbohydrates are linked together to form disaccharides and other polysaccharides through glycosidic linkages. A glycosidic linkage is one in where two sugar molecules are bridged by an oxygen atom. Peptide linkages are found between amino acids and phosphodiester bonds are found between nucleic acid monomers. Ionic bonds involve the complete transfer of one or more electrons from one species to another. Hydrogen bonds are weak intermolecular and intramolecular forces that contribute to the stability of many substances such as liquid water.

7

Which of the following requires a carrier protein in order to be transported through the bloodstream?

Steroid

Sucrose

Glycine

ATP

Explanation

Blood is an aqueous solution and will easily dissolve polar, hydrophilic molecules. Nonpolar molecules, however, do not easily exist in this solution and require a bound polar group, such as a carrier protein, to exist in equilibrium.

Proteins, carbohydrates, and nucleic acids all contain polar groups, allowing them to dissolve in the blood. Lipids, however, are nonpolar and require transport proteins. Steroids are a class of lipids and will require protein assistance for transport in the blood.

Sucrose is a carbohydrate, glycine is a polar amino acid, and ATP is a polar nucleic acid derivative.

8

Which of the following requires a carrier protein in order to be transported through the bloodstream?

Steroid

Sucrose

Glycine

ATP

Explanation

Blood is an aqueous solution and will easily dissolve polar, hydrophilic molecules. Nonpolar molecules, however, do not easily exist in this solution and require a bound polar group, such as a carrier protein, to exist in equilibrium.

Proteins, carbohydrates, and nucleic acids all contain polar groups, allowing them to dissolve in the blood. Lipids, however, are nonpolar and require transport proteins. Steroids are a class of lipids and will require protein assistance for transport in the blood.

Sucrose is a carbohydrate, glycine is a polar amino acid, and ATP is a polar nucleic acid derivative.

9

What is the main difference between DNA nucleotides and RNA nucleotides?

RNA nucleotides have two hydroxide groups on the sugar, but DNA nucleotides have only one

DNA has uracil, while RNA has thymine

DNA nucleotides are bound by phosphodiester bonds, but RNA nucleotides are bound by glycosidic bonds

RNA nucleotides have five-carbon sugars, while DNA nucleotides have six-carbon sugars

RNA nucleotide bases pair via hydrogen bonds, but DNA nucleotide bases do not

Explanation

The correct answer is that RNA nucleotides have two hydroxide groups on the sugar, whereas DNA nucleotides have only one hydroxide group. RNA uses uracil in place of thymine; not DNA. Both DNA and RNA have five-carbon sugars and are bound together along the backbone by phosphodiester bonds. Though base pairing is more common in DNA (double-stranded RNA is less common), both utilize hydrogen bonding.

10

What is the main difference between DNA nucleotides and RNA nucleotides?

RNA nucleotides have two hydroxide groups on the sugar, but DNA nucleotides have only one

DNA has uracil, while RNA has thymine

DNA nucleotides are bound by phosphodiester bonds, but RNA nucleotides are bound by glycosidic bonds

RNA nucleotides have five-carbon sugars, while DNA nucleotides have six-carbon sugars

RNA nucleotide bases pair via hydrogen bonds, but DNA nucleotide bases do not

Explanation

The correct answer is that RNA nucleotides have two hydroxide groups on the sugar, whereas DNA nucleotides have only one hydroxide group. RNA uses uracil in place of thymine; not DNA. Both DNA and RNA have five-carbon sugars and are bound together along the backbone by phosphodiester bonds. Though base pairing is more common in DNA (double-stranded RNA is less common), both utilize hydrogen bonding.

Page 1 of 3