Chapter 9 Questions

Which of the following statements is false? (a) The human genome is more similar to the orangutan genome than it is to the mouse genome. (b) A comparison of genomes shows that 90% of the human genome shares regions of conserved synteny with the mouse genome. (c) Primates, dogs, mice, and chickens all have about the same number of genes. (d) Genes that code for ribosomal RNA share significant similarity in all eukaryotes but are much more difficult to recognize in archaea.

(c) Primates, dogs, mice, and chickens all have about the same number of genes.

A protein normally expressed only in the liver is now expressed in blood cells. ________ A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

C) mutation in a regulatory region

Viral genomes _________. (a) can be made of DNA. (b) can be made of RNA. (c) can be either double-stranded or single-stranded. (d) All answers above are true.

(d) All answers above are true.

Mobile genetic elements are sometimes called "jumping genes," because they move from place to place throughout the genome. The exact mechanism by which they achieve this mobility depends on the genes contained within the mobile element. Which of the following mobile genetic elements carries both a transposase gene and a reverse transcriptase gene? (a) L1 (b) B1 (c) Alu (d) Tn3

(a) L1

A protein becomes much more unstable. _________ A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

A) mutation within a gene

Which of the following statements about gene families is false? (a) Because gene duplication can occur when crossover events occur, genes are always duplicated onto homologous chromosomes. (b) Not all duplicated genes will become functional members of gene families. (c) Whole-genome duplication can contribute to the formation of gene families. (d) Duplicated genes can diverge in both their regulatory regions and their coding regions.

(a) Because gene duplication can occur when crossover events occur, genes are always duplicated onto homologous chromosomes.

Which of the following generalities about genomes is true? (a) All vertebrate genomes contain roughly the same number of genes. (b) All unicellular organisms contain roughly the same number of genes. (c) The larger an organism, the more genes it has. (d) The more types of cell an organism has, the more genes it has.

(a) All vertebrate genomes contain roughly the same number of genes.

Which of the following statements about what we have learned by comparing the modern-day human genome to other genomes is true? (a) Modern humans whose ancestors come from Europe or Asia share up to 4 percent of their genome with Neanderthals. (b) Accelerated changes, which were found when comparing the human genome to other mammalian genomes, were not found when comparing the modern-day human genome to the Neanderthal genome. (c) The human genome is far more gene-dense than the yeast genome. (d) In syntenic regions of the human and mouse genomes, both gene order and the placements of more than 95% of the mobile genetic elements are conserved.

(a) Modern humans whose ancestors come from Europe or Asia share up to 4 percent of their genome with Neanderthals.

Which of the following statements is false? A) A mutation that arises in a mother's somatic cell often causes a disease in her daughter. B) All mutations in an asexually reproducing single-celled organism are passed on to progeny. C) In an evolutionary sense, somatic cells exist only to help propagate germ-line cells D) A mutation is passed on to offspring only if it is present in the germ line.

A) A mutation that arises in a mother's somatic cell often causes a disease in her daughter.

A protein normally localized in the nucleus is now localized in the cytoplasm. A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

A) mutation within a gene

A protein normally localized in the nucleus is now localized in the cytoplasm. A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

A) mutation within the gene

Which of the following statements about retroviruses is false? (a) Retroviruses are packaged with a few molecules of reverse transcriptase in each virus particle. (b) Retroviruses use the host-genome integrase enzyme to create the provirus. (c) The production of viral RNAs can occur long after the initial infection of the host cell by the retrovirus. (d) Viral RNAs are translated by host-cell ribosomes to produce the proteins required for the production of viral particles.

(b) Retroviruses use the host-genome integrase enzyme to create the provirus.

Which of the following statements is true? (a) The intron structure of most genes is conserved among vertebrates. (b) The more nucleotides there are in an organism's genome, the more genes there will be in its genome. (c) Because the fly Drosophila melanogaster and humans diverged from a common ancestor so long ago, a gene in the fly will show more similarity to another gene from the same species than it will to a human gene. (d) An organism from the same Order as another will be more likely to have a genome of the same size than will a more evolutionarily diverged animal.

DON'T KNOW ITS EITHER (a) The intron structure of most genes is conserved among vertebrates. OR (c) Because the fly Drosophila melanogaster and humans diverged from a common ancestor so long ago, a gene in the fly will show more similarity to another gene from the same species than it will to a human gene.

A copy of a bacterial gene is now found integrated on a human chromosome. _________ A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

E) horizontal gene transfer

The number of distinct protein species found in humans and other organisms can vastly exceed the number of genes. This is largely due to ______________. (a) protein degradation. (b) alternative splicing. (c) homologous genes. (d) mutation.

(b) alternative splicing.

Which of the following DNA sequences is not commonly carried on a DNA-only transposon? (a) transposase gene (b) reverse transcriptase gene (c) recognition site for transposase (d) antibiotic-resistance gene

(b) reverse transcriptase gene

Which of the following changes is least likely to arise from a point mutation in a regulatory region of a gene? (a) a mutation that changes the time in an organism's life during which a protein is expressed (b) a mutation that eliminates the production of a protein in a specific cell type (c) a mutation that changes the subcellular localization of a protein (d) a mutation that increases the level of protein production in a cell

(c) a mutation that changes the subcellular localization of a protein

Which of the following statements about the human genome is false? (a) About 50% of the human genome is made up of mobile genetic elements. (b) More of the human genome comprises intron sequences than exon sequences. (c) About 1.5% of the human genome codes for exons. (d) Only the exons are conserved between the genomes of humans and other mammals.

(d) Only the exons are conserved between the genomes of humans and other mammals.

Which of the following would contribute most to successful exon shuffling? a) shorter introns (b) a haploid genome (c) exons that code for more than one protein domain (d) introns that contain regions of similarity to one another

(d) introns that contain regions of similarity to one another

You isolate a pathogenic strain of E. coli from a patient and discover that this E. coli strain is resistant to an antibiotic. Common laboratory strains of E. coli are not resistant to this antibiotic, nor are any other previously isolated pathogenic E. coli strains. However, such resistance has been observed in other bacteria in the hospital in which the patient was treated. This newly discovered antibiotic resistance in E. coli is most likely due to (a) a mutation within a gene. (b) a mutation within the regulatory DNA of a gene. (c) gene duplication. (d) horizontal gene transfer.

d) horizontal gene transfer.

Tandem copies of a gene are found in the genome. A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

B) gene duplication

A protein acquires a DNA-binding domain. A) mutation within a gene B) gene duplication C) mutation in a regulatory region D) exon shuffling E) horizontal gene transfer

D) exon shuffling

Most variation between individual humans is in the form of __________________. __________________ may arise by recombination within introns and can create proteins with novel combinations of domains. Scientists and government regulators must be very careful when introducing herbicide-resistant transgenic corn plants into the environment, because if resistant weeds arise from __________________ then the herbicides could become useless. Families of related genes can arise from a single ancestral copy by __________________ and subsequent __________________. - Divergence - Exon Shuffling - Gene duplication - Horizontal gene transfer - Purifying selection - Single-nucleotide polymorphisms - Synteny - Unequal crossing-over

Most variation between individual humans is in the form of SINGLE NUCLEOTIDE POLYMORPHISMS. EXON SHUFFLING may arise by recombination within introns and can create proteins with novel combinations of domains. Scientists and government regulators must be very careful when introducing herbicide-resistant transgenic corn plants into the environment, because if resistant weeds arise from HORIZONTAL GENE TRANSFER then the herbicides could become useless. Families of related genes can arise from a single ancestral copy by GENE DUPLICATION and subsequent DIVERGENCE.

Sexual reproduction in a multicellular organism involves specialized reproductive cells, called __________________s, which come together to form a __________________ that will divide to produce both reproductive and __________________ cells. A point mutation in the DNA is considered a __________________ mutation if it changes a nucleotide that leads to no phenotypic consequence; a point mutation is considered __________________ if it changes a nucleotide within a gene and causes the protein to be nonfunctional. - Cellulose - Common - Deleterious - Gamete - Homologous - Intron - Neutral - Somatic - Unequal - Zygote

Sexual reproduction in a multicellular organism involves specialized reproductive cells, called GAMETEs, which come together to form a ZYGOTE that will divide to produce both reproductive and SOMATIC cells. A point mutation in the DNA is considered a NEUTRAL mutation if it changes a nucleotide that leads to no phenotypic consequence; a point mutation is considered DELETERIOUS if it changes a nucleotide within a gene and causes the protein to be nonfunctional.

For each statement below, indicate whether it is true or false, and explain why. A. All highly conserved stretches of DNA in the genome are transcribed into RNA. B. To find functionally important regions of the genome, it is more useful to compare species whose last common ancestor lived 100 million years ago rather than 5 million years ago. C. Most mutations and genome alterations have neutral consequences. D. Proteins required for growth, metabolism, and cell division are more highly conserved than those involved in development and in response to the environment. E. Introns and transposons tend to slow the evolution of new genes.

TRUE STATEMENTS B. To find functionally important regions of the genome, it is more useful to compare species whose last common ancestor lived 100 million years ago rather than 5 million years ago. C. Most mutations and genome alterations have neutral consequences. D. Proteins required for growth, metabolism, and cell division are more highly conserved than those involved in development and in response to the environment. FALSE STATEMENTS A. All highly conserved stretches of DNA in the genome are transcribed into RNA. E. Introns and transposons tend to slow the evolution of new genes.