4. Biomolecules

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

The four nitrogenous bases commonly found if DNA are:

Which of the following statements about DNA structure is true?

What are the four nitrogenous bases found in RNA?

a. Cytosine, guanine, thymine, uracil (C, G, T, U)

b. Adenine, cytosine, guanine, thymine (A, C, G, T)

c. Adenine, cytosine, guanine, uracil (A, C, G, U)

d. Alanine, cysteine, glycine, threonine (A, C, G, T)

What determines the primary structure of a DNA molecule?

a. Stem-and-loop configuration

b. Complementary base pairing

c. Deoxyribonucleotide sequence

d. Hydrophobic interactions and hydrogen bonding

Evaluate the following statements related to the synthesis of nucleic acids. Select True or False for each statement.

T/F Ribonucleotides are added to the 3′ end of a DNA strand.

T/F Polymerization of nucleic acids occurs by the formation of phosphodiester bonds.

T/F Complementary pairing between sugars is required for copying nucleic acids.

T/F Strands in a double helix are synthesized in an antiparallel orientation.

Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand?

What is responsible for the increased stability of DNA compared to RNA?

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

a. The two strands of the double helix would separate.

b. The phosphodiester linkages of the polynucleotide backbone would be broken.

c. The pyrimidines would be separated from the deoxyribose sugars.

d. All bases would be separated from the deoxyribose sugars.