Chapter 16

In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.

1'.... 5'

Nucleic acids are assembled in the _____ direction.

5' to 3'

Given a template strand of 3'-ATGCTTGGACA-5' and a partially-made complementary strand containing only 5'-TAC-3', what would be the sequence of the new strand of DNA (including the 5'-TAC-3') if the only additional nucleotides available to DNA polymerase were those containing the bases G, A, and C?

5'-TACGAACC-3'

In the accompanying image, a nucleotide is indicated by the letter _____. The figure shows the double stranded DNA. Each letter marks the definite element of the DNA. Letter A marks the full turn of DNA. Letter B marks chemical compound, which is a structural element of DNA. Letter C marks two chains of DNA and the bonds between them. Letter D marks one chain of the DNA.

B

PO4 indicates a

Phosphate Group

Which of these is(are) pyrimidines?

Pyrimidines are single-ring structures

Addition of a nucleotide onto a DNA strand is an endergonic reaction. What provides the energy to drive the reaction?

Release of pyrophosphate from the incoming nucleotide, and then hydrolysis of the pyrophosphate to inorganic phosphate

The bonds or interactions between stacked nucleotide units that help hold the DNA molecule together are

Van der Waals Interactions

Which of the following diagrams most clearly shows the details of the bonds between nitrogenous bases of complementary nucleotide pairs?

While the complementary nature of the interactions between the base pairs is demonstrated in all four diagrams, only the structural diagram shows the molecular details--the specific number and location of hydrogen bonds that form between complementary base pairs.

Nucleotides are composed of

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

A hydroxyl is present at the 3' end of the growing DNA strand. What is at the 5' end?

a phosphate group

What materials does DNA polymerase require in order to synthesize a complete strand of DNA?

single-stranded DNA template, 3'-OH end of the new DNA strand, all four deoxyribonucleotides triphosphates (containing A, C, T, or G)

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

sugar with two, and not three, oxygen atoms

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

Which of these is a difference between a DNA and an RNA molecule?

DNA is usually double-stranded, whereas RNA is usually single-stranded.

What is the role of DNA polymerase during DNA synthesis?

DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3' end of a growing DNA strand.

The bonds or interactions that hold together complementary bases from opposite strands of DNA are

Hydrogen Bonds

Nitrogenous Base

NH2N2OH2

Which of the following diagrams most clearly shows the overall 3D shape and atomic composition of DNA?

The space-filling model shows each atom making up the two strands, and reveals the helical shape and the double-stranded structure of the DNA molecule.

Which of these nitrogenous bases is found in DNA but not in RNA?

Thymine

Duplication of chromosomes occurs during S phase of the cell cycle. Duplication requires the separation of complementary DNA strands to allow for DNA replication. Which of the following statements best explains how weak hydrogen bonds function better in this situation than stronger bonds would? Duplication of chromosomes occurs during S phase of the cell cycle. Duplication requires the separation of complementary DNA strands to allow for DNA replication. Which of the following statements best explains how weak hydrogen bonds function better in this situation than stronger bonds would?

Complementary DNA strands are separated or "unzipped" for the replication process. Weak hydrogen bonds between complementary strands are easily disrupted during DNA replication because they are not high-energy chemical bonds.

The bonds or interactions that hold together adjacent nucleotides in the sugar-phosphate backbone of DNA are

Covalent Bonds