Which of the following descriptions best fits the class of molecules known as nucleotides?

a nitrogenous base, a phosphate group, and a pentose sugar

A molecule with the formula C₁₈H₃₆O₂ is probably a

fatty acid.

Which of the following statements best summarizes the differences between DNA and RNA?

DNA nucleotides contain a different sugar than RNA nucleotides.

What aspects of protein structure are stabilized or assisted by hydrogen bonds?

secondary, tertiary, and quaternary structures, but not primary structure

Which class of biological molecules are grouped together because they are hydrophobic?

lipids

Which class of biological molecules are grouped together because their monomers are amino acids?

proteins

What is the structural feature that allows DNA to replicate?

complementary pairing of the nitrogenous bases

Molecules with which functional groups may form polymers via dehydration reactions?

either hydroxyl or carboxyl groups

If cells are grown in a medium containing radioactive ¹⁵N, which of these molecules will be labelled?

both proteins and nucleic acids

The basis for diversity, both within a species and among species, is a result of the

arrangement of a few base molecules into many different macromolecular combinations.

The following questions are based on the 15 molecules illustrated in the figure below. Each molecule may be used once, more than once, or not at all.

Which of the following molecules consists of a hydrophilic "head" region and a hydrophobic "tail" region?

5

Which of the following molecules could be joined together by a phosphodiester type of covalent bond?

11 and 12

Which of the following molecules could be joined together by a peptide bond as a result of a dehydration reaction?

7 and 8

Which of the following molecules act as building blocks (monomers) of polypeptides?

2,7, and 8

Which of the following statements is/are true regarding the chemical reaction illustrated in the figure above?

It results in a peptide bond.

Which of the following is an example of hydrolysis?

the reaction of a fat, forming glycerol and fatty acids with the consumption of water

Which level of protein structure do the α helix and the β pleated sheet represent?

secondary

If cells are grown in a medium containing radioactive ³⁵S, which of these molecules will be labelled?

proteins

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?

40

Which of the following are nitrogenous bases of the pyrimidine type?

cytosine and uracil

Which bonds are created during the formation of the primary structure of a protein?

peptide bonds

At which level of protein structure are interactions between the side chains (R groups) most important?

tertiary

Which of the following are nitrogenous bases of the purine type?

guanine and adenine

The tertiary structure of a protein is the

unique three-dimensional shape of the fully folded polypeptide.

Which of the following is true of cellulose?

It is a major structural component of plant cell walls.

Which of these classes of biological molecules consist of both small molecules and macromolecular polymers?

carbohydrates

The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by

hydrogen bonds.

Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibres. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits

altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down?

glycogen

Which of the following polymers contain nitrogen?

chitin