Download Answers to End-of-Chapter Questions – Brooker et al ARIS site

Answers to End-of-Chapter Questions – Brooker et al ARIS site
Chapter 21
Test Yourself Questions
1. The entire collection of proteins produced by a cell or organism is
a. a genome.
b. bioinformatics.
c. a proteome.
d. a gene family.
e. a protein family.
Answer: c. The proteome includes all of the proteins produced by a cell or organism.
2. Important reasons for studying the genomes of prokaryotes include all of the following except
a. It may provide information that helps us understand how prokaryotes infect other organisms.
b. It may provide a basic understanding of cellular processes that allow us to determine
eukaryotic cellular function.
c. It may provide the means to understand evolutionary processes.
d. It will reveal the approximate number of genes that an organism has in its genome.
e. All of the above are important reasons.
Answer: e. All of the above are important reasons.
3. The enzyme that allows short segments of DNA to move within a cell from one location in the genome
to another is
a. transposase.
b. DNA polymerase.
c. protease.
d. restriction endonuclease.
e. reverse transcriptase.
Answer: a. Transposase is the enzyme that facilitates transposition.
4. A gene family includes
a. a specific gene found in several different species that has a similar DNA sequence.
b. all the genes on the same chromosome.
c. two or more homologous genes found within a single species.
d. genes that code for structural proteins.
e. both a and c.
Answer: c. A gene family is a group of homologous genes within a single species.
5. Which of the following is not a goal of the Human Genome Project?
a. Identify all human genes.
b. Sequence the entire human genome.
c. Address the legal and ethical implications resulting from the project.
d. Develop programs to manage the information gathered from the project.
e. Clone a human.
Answer: e. Cloning humans is not a goal of the Human Genome Project.
6. Bioinformatics is
a. the analysis of DNA by molecular techniques.
b.
c.
d.
e.
the use of computers to analyze and store biological information.
a collection of gene sequences from a single individual.
cloning.
all of the above.
Answer: b. Bioinformatics is the use of computers to analyze and store biological information.
7. Using bioinformatics, evolutionary relationships between species can be characterized by identifying
and analyzing
a. phenotypes of selected organisms.
b. homologous DNA sequences.
c. fossils of ancestral species.
d. all of the above.
e. a and b only.
Answer: b. Homologous DNA sequences are found between closely related species. Their analysis can
reveal how closely related species are evolutionarily.
8. The BLAST is a program that
a. inserting many DNA fragments into a cell at the same time.
b. translating a DNA sequence into an amino acid sequence.
c. identifying homology between a selected sequence and genetic sequences in large
databases.
d. all of the above
e. both b and c.
Answer: c. The BLAST program is useful because it can identify homology among DNA sequences in
very large databases.
9. Repetitive sequences
a. are short DNA sequences that are found many times throughout the genome.
b. may be multiple copies of the same gene found in the genome.
c. are more common in eukaryotes.
d. all of the above.
e. a and c only.
Answer: d. Repetitive sequences are short DNA sequences found many times throughout the genome.
They are more common in eukaryotes. Some moderately repetitive sequences are multiple copies of the
same gene, such as the rRNA gene.
10. Proteins that provide movement of material inside the cell and movement of the entire cell are
a. enzymes.
b. structural proteins.
c. motor proteins.
d. transport proteins.
e. antibodies.
Answer: d. Motor proteins are involved in intracellular movement and movement of the entire cell.
Conceptual Questions
1. Define bioinformatics.
A field of study that uses computers to study biological information.
2. Explain how homologous genes may have arisen.
Answer: A common mechanism that produces new gene duplications is a misaligned crossover. Two
homologous chromosomes pair with each other but their alignment is not perfect. If a crossover occurs
in this misaligned region, one chromosome will have a gene duplication and one will have a deletion.
3. What are seven general categories of proteins found in the proteome?
Answer:
1.
2.
3.
4.
5.
6.
7.
Metabolic enzymes
Structural proteins
Motor proteins
Cell signaling proteins
Transport proteins
Gene expression and regulation proteins
Protective proteins
Experimental Questions
1. What was the goal of the experiment conducted by Venter, Smith, and their colleagues?
Answer: The goal of the experiment was to sequence the entire genome of Haemophilus influenzae. By
conducting this experiment, the researchers would have information about genome size and the types
of genes the bacterium has.
2. How does shotgun DNA sequencing differ from procedures that involve mapping? What are an
advantage and a disadvantage of the shotgun DNA sequencing approach?
Answer: One strategy requires mapping the genome prior to sequencing. After mapping is completed
each region of the genome is then sequenced. The shot-gun approached does not require mapping of
the genome prior to sequencing. Instead, many fragments are randomly sequenced.
The advantage is the speed at which the sequencing can be conducted because the researchers do not
have to spend time mapping the genome first. The disadvantage is that since the researchers are
sequencing random fragments, some fragments may be sequenced more than once.
3. What were the results of the study described in Figure 21.1?
Answer: The researchers were successful in sequencing the entire genome of the bacterium. The
genome size was determined to be 1,830,137 bases pairs, with a predicted 1,743 structural genes. The
researchers were also able to predict the function of many of these genes. More importantly, the results
were the first complete genomic sequence of a living organism.
Collaborative Questions
1. Compare the genomes of prokaryotic and eukaryotic organisms.
Answer: The prokaryotic genome typically consists of a single chromosome ranging from several
hundred thousand to a few million base pairs in length. Most prokaryotes contain only a single
chromosome although there may be multiple copies present within a single cell. Bacterial chromosomes
are predominantly circular in structure although linear chromosomes are found in several species. When
compared to the eukaryotic genome, the prokaryotic genome is less complex lacking centromeres and
telomeres and has a single origin of replication. In addition, the prokaryote genome has relatively little
repetitive DNA.
The genome found in eukaryotes is usually found in sets of linear chromosomes. The genome of simple
eukaryotes carry only a few thousand genes while the genome of more complex eukaryotes may
contain tens of thousands of genes. Unlike the genome of prokaryotes, the chromosomes found in
eukaryotes are much more complex having centromeres, telomeres, and multiple origins of replication.
And unlike prokaryotes, eukaryotes have more repetitive DNA ranging from moderate to high.
2. Discuss the concept and importance of transposable elements.
Answer: The genome of many organisms can sometimes be moderately to highly repetitive with respect
to certain types of sequences. Much of the repetitive DNA is due to a process called transposition,
which is when a short segment of DNA moves to a new site in the genome. The DNA sequences that
transpose themselves are referred to as transposable elements or sometimes called "jumping genes".
The significance of transposable elements remains a matter of debate within the scientific community.
One hypothesis proposes that the transposable elements provide the organism with a survival
advantage by causing greater genetic variability by promoting chromosomal rearrangement. But, if a
transposable element jumps into the middle of an important gene sequence then the transposable
element may disrupt its function, thus having a negative impact on the organism.