Question 1

Which of the following lists represents the order of increasingly higher levels of organization of chromatin?

Accepted Answer

A)   nucleosome, 30-nm chromatin fiber, looped domain
B)   looped domain, 30-nm chromatin fiber, nucleosome
C)   nucleosome, looped domain, 30-nm chromatin fiber
D)   30-nm chromatin fiber, nucleosome, looped domain A

Question 2

Which of the following combinations of base pairs will be found in a molecule of DNA?

Accepted Answer

A)   A = C
B)   A = G and C = T
C)   A + C = G + T
D)   G + C = T + A C

Question 3

Frederick Griffith heat-killed a culture of pathogenic bacteria. He split the sample and injected half of it into mice. The mice lived. He then mixed the other half with a living, nonpathogenic bacteria strain and injected the mixture into mice. The mice died. These results best support which of the following conclusions.

Accepted Answer

A)   the initial heat treatment was unsuccessful
B)   splitting the culture revived the pathogenic bacteria
C)   non-pathogenic bacteria were transformed by pathogenic capsule proteins
D)   a substance had been transferred from pathogenic to nonpathogenic bacteria D

Question 4

Hershey and Chase set out to determine which type of molecule is used for genetic inheritance. They completed a series of experiments where E. coli was infected by a T2 virus. Which molecular component of the T2 virus ended up inside the cell?

Accepted Answer

A)   protein
B)   RNA
C)   ribosome
D)   DNA

Question 5

Which of the following statements describes the process of transformation in bacteria?

Accepted Answer

A)   A strand of DNA is created from an RNA molecule.
B)   A strand of RNA is created from a DNA molecule.
C)   Bacterial cells are infected by a phage DNA molecule.
D)   External DNA is taken into a cell, becoming part of the cell's genome.

Question 6

Which of the following types of molecules help to hold the DNA strands apart while they are being replicated?

Accepted Answer

A)   primase
B)   ligase
C)   DNA polymerase
D)   single-strand DNA binding proteins

Question 7

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction?

Accepted Answer

A)   primase
B)   DNA ligase
C)   DNA polymerase III
D)   helicase

Question 8

In DNA replication in E. coli, the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following results would you expect?

Accepted Answer

A)   Replication would only occur on the leading strand.
B)   Replication would only occur on the lagging strand.
C)   Replication would not occur on either the leading or lagging strand.
D)   Replication would not be affected as the enzyme primase in involved with RNA synthesis.

Question 9

What catalyzes the formation of phosphodiester bonds between a DNA strand and a new nucleotide being added during DNA replication?

Accepted Answer

A)   Primase
B)   DNA polymerase
C)   ATP
D)   Helicase

Question 10

In DNA polymerization, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and which of the following atoms or molecules of the last nucleotide in the polymer?

Accepted Answer

A)   the 5' phosphate
B)   C6
C)   the 3' OH
D)   a nitrogen from the nitrogen-containing base

Question 11

Which of the following is most likely to result if a cell is unable to produce histone proteins?

Accepted Answer

A)   there would be an increase in the amount of DNA produced during replication
B)   the cell's DNA could not be packed into its nucleus
C)   the 30-nm fiber pack more tightly and become thinner than 30 nm
D)   topoisomerases in the 300-nm fiber scaffolding would not need to be as active

Question 12

Histone proteins contain internal cores that are hydrophobic and surface amino acids that are positively charged. Which of the following characteristics of DNA would best support tight binding between DNA and histones?

Accepted Answer

A)   the ring structures in DNA bases that disperse charge promote hydrophobic interactions with histone cores
B)   DNA 5' and 3' ends have negative charge responsible for stabilizing interactions with histone surfaces
C)   the DNA backbone has a net negative charge that forms ionic bonds with histones
D)   the 3.4 nm per helical turn in DNA fits around the spherical shape of the histones

Question 13

A phosphorescent red strain of bacteria is heat-killed and mixed with a living, colorless strain. Further observations of the mixture show that some of the living cells are now red. Which of the following observations would provide the best evidence that red color is a heritable trait?

Accepted Answer

A)   especially bright red color in some members of the living strain
B)   as the living cells divide the number of red cells increases
C)   when the heat-killed and living cells are mixed there is a decrease in the overall amount of red color
D)   after a few generations there are no more colorless cells, all cells are red

Question 14

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

Accepted Answer

A)   The The origins of replication occur only at the 5' end.
B)   Helicases and single-strand binding proteins work at the 5' end.
C)   DNA polymerase can join new nucleotides only to the 3' end of a pre-existing strand, and the strands are antiparallel.
D)   DNA ligase works only in the 3' → 5' direction.

Question 15

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

Accepted Answer

A)   one high-density and one low-density band
B)   one intermediate-density band
C)   one high-density and one intermediate-density band
D)   one low-density and one intermediate-density band

Question 16

Which of the following structural characteristics is most critical for the association between histones and DNA?

Accepted Answer

A)   Histones are small proteins.
B)   Histones are highly conserved (that is, histones are very similar in every eukaryote) .
C)   There are at least five different histone proteins in every eukaryote.
D)   Histones are positively charged.

Question 17

Which of the following statements correctly describes the difference between ATP used in metabolism and the nucleotides used as a building block during DNA synthesis?

Accepted Answer

A)   The nucleotides have the sugar deoxyribose; ATP has the sugar ribose.
B)   The nucleotides have two phosphate groups; ATP has three phosphate groups.
C)   ATP contains three high-energy bonds; the nucleotides have two.
D)   ATP is found only in human cells; the nucleotides are found in all animal and plant cells.

Question 18

The sequence of nucleotides below is present at a DNA location where the chain opens to form a replication fork:
3' C C T A G G C T G C A A T C C 5'
An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

Accepted Answer

A)   5' A G C C U A G G 3'
B)   5' A C G T T A G G 3'
C)   5' A C G U U A G G 3'
D)   5' A G C C T A G G 3'

Question 19

A sample of double-stranded DNA contains 28% thymine. Approximately what percent of the nucleotides in this sample will be guanine?

Accepted Answer

A)   8%
B)   16%
C)   22%
D)   72%

Question 20

The lagging strand is characterized by a series of short segments of DNA (Okazaki fragments) that are joined together to form a finished lagging strand. The experiments that led to the discovery of Okazaki fragments gave evidence for which of the following ideas?

Accepted Answer

A)   DNA polymerase synthesizes leading and lagging strands during replication only in one direction.
B)   DNA is a polymer consisting of four monomers: adenine, thymine, guanine, and cytosine.
C)   DNA is the genetic material that requires removal of short RNA segments to be functional.
D)   Bacterial replication is fundamentally different from eukaryotic replication.

Exam 16: Nucleic Acids and Inheritance