Chapter 16: How Genes Work

Question 1

1) Which of the following contradicts the one-gene, one-enzyme hypothesis?
A) A mutation in a single gene can result in a defective protein.
B) Alkaptonuria results when individuals lack a single enzyme involved in the catalysis of homogentisic acid.
C) Sickle cell anemia results in defective hemoglobin.
D) A single antibody gene can code for different related proteins, depending on the
splicing that takes place post-transcriptionally.

Answer 1

D) A single antibody gene can code for different related proteins, depending on the
splicing that takes place post-transcriptionally.

Question 2

2) Beadle and Tatum discovered that metabolic pathways are studied most effectively using which of the following techniques?
A) using multiple gene mutations resulting in nonfunctional enzymes specific to a metabolic pathway
B) adding intermediates to a metabolic pathway
C) removing all intermediates of a metabolic pathway
D) using single gene mutations resulting in nonfunctional enzymes specific to a metabolic pathway

Answer 2

D) using single gene mutations resulting in nonfunctional enzymes specific to a
metabolic pathway

Question 3

3) Refer to the associated figure. A branched metabolic pathway synthesizes two related amino acids (D and F). If there is a genetic defect, resulting in a nonfunctional enzyme (3), how could you ensure that adequate amounts of the amino acid F are synthesized?
A) supplement intermediate B
B) supplement intermediate C
C) add enzyme 2 to the medium
D) supplement with intermediate E

Answer 3

D) supplement with intermediate E

Question 4

4) According to the table and the figure associated with this question, which enzyme is
defective in the strain with the arg2 mutation?
A) the enzyme that converts the precursor to ornithine
B) the enzyme that converts ornithine to citrulline
C) the enzyme that converts citrulline to arginine
D) the enzyme that converts the precursor to citrulline

Answer 4

B) the enzyme that converts ornithine to citrulline

Question 5

5) Knockout mice have been genetically altered to knock out specific genes. How are these mice most often used in research?
A) to study DNA replication in the defective genes (those that have been altered)
B) to determine the role of proteins coded for by those genes that are knocked out
C) to examine defects in DNA structure in those regions that have been altered
D) to study the effect of radiation on DNA

Answer 5

B) to determine the role of proteins coded for by those genes that are knocked out

Question 6

6) Refer to the associated figure. In the branched metabolic pathway indicated in the
figure, if enzyme 3 is defective and the amount of each enzyme is constant, you might expect to see an increase in the amount of which intermediate or product?
A) E
B) B
C) F
D) D

Answer 6

B) B

Question 7

7) The proteome is all the proteins produced by an organism. The genome is the totality of all genes of an organism. If the proteome is much larger than the genome, which of the following statements would be accurate?
A) This finding lends support to a one-gene, two-enzyme hypothesis.
B) The number of monomeric subunits found in proteins is fewer than the number of
monomeric subunits found in genes.
C) At least in some cases, a single gene must code for more than one protein.
D) Noncoding DNA is important in determining the proteome.

Answer 7

C) At least in some cases, a single gene must code for more than one protein.

Question 8

8) Refer to the metabolic pathway illustrated in the associated figure. If A, B, and C are all required for growth, a strain mutant for the gene encoding enzyme B would be able to grow on medium supplemented with ________.
A) nutrient A only
B) nutrient B only
C) nutrient C only
D) nutrients A and C

Answer 8

C) nutrient C only

Question 9

9) In the Morse code, a series of dots and dashes code for letters of the alphabet. How is this analogous to the genetic code?
A) There is complementarity in the genetic code (A is complementary to T, and C is
complementary to G).
B) The bases that make up DNA are coded by the sugar-phosphate backbone.
C) The machinery involved in DNA synthesis is analogous to the telegraph equipment
used in sending Morse code.
D) The bases of DNA code for the more complex amino acid sequence of the proteins
in cells.

Answer 9

D) The bases of DNA code for the more complex amino acid sequence of the proteins
in cells.

Question 10

10) Which of the following is NOT synthesized from a DNA template?
A) messenger RNA
B) amino acids
C) transfer RNA
D) ribosomal RNA

Answer 10

B) amino acids

Question 11

11) In the process of transcription, ________.
A) DNA is replicated
B) RNA is synthesized
C) proteins are synthesized
D) mRNA attaches to ribosomes

Answer 11

B) RNA is synthesized

Question 12

12) Given the DNA template shown in the associated figure, which of the following bases
would you find in a complementary RNA strand and where would they be synthesized?
A) A-A-A-A-A; nucleus
B) U-U-U-U-U; nucleus
C) A-A-A-A-A; ribosome
D) U-U-U-U-U; ribosome
Answer: A

Question 13

13) In the first step of their experiments, Jacob and Monod treated E. coli cells with
ultraviolet light or X-rays to ________.
A) decrease the rate of gene expression
B) induce DNA repair enzymes
C) increase the frequency of mutations in all genes
D) selectively mutate specific genes, leaving all other genes unmutated
Answer: C

Question 14

14) All three domains (Bacteria, Archaea, and Eukarya) follow the same genetic code.
Therefore, which of the following statements would most likely be correct?
A) The genetic code evolved three times.
B) The genetic code evolved before DNA replaced RNA as the unit of genetic
information.
C) There were no mutations following the evolution of the genetic code.
D) The genetic code evolved before the different domains diverged.
Answer: D

Question 15

15) Genotype is to ________ as phenotype is to ________.
A) DNA base sequence; physical traits that are products of the proteins produced
B) heredity; DNA base sequence
C) gene regulation; translation
D) transcription; amino acid sequence
Answer: A

Question 16

16) Which of the following is an exception to the central dogma?
A) the discovery of RNA viruses that synthesize DNA using reverse transcriptase
B) the discovery that the Archaea and Bacteria are more distantly related than are
Archaea and Eukarya
C) the discovery of ribozymes
D) the discovery of DNA as the unit of genetic inheritance
Answer: A

Question 21

21) How does the simple primary and secondary structure of DNA hold the information
needed to code for the many features of multicellular organisms?
A) The hydrogen bonding among backbone constituents carries coded information.
B) The base sequence of DNA carries the information needed to code for proteins.
C) The width of the double helix changes at each gene due to differences in hydrogen
bonds.
D) The amino acids that make up the DNA molecule contain the information needed to
make cellular proteins.
Answer: B