ECS: Exam 2 - Chapter 9

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 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 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) 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 - Information for the subcellular localization of a protein is usually encoded within the translated portion of the gene.

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

You isolate an antibiotic resistant strain of E. coli from a patient. This is not common for E. coli, however this resistance has been observed in other strains of bacteria in the hospital. This is likely due to what? (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

For each statement below, indicate whether it is true or false, 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.

A - False - a lot of highly conserved portions of the genome are used for regulation of transcripton. B - True - functionally important genes persist over time because an organism would not have been fit for life without them. C - True - most mutations do not change the amino acid sequence so they don't have an effect on protein function.

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.

A - I think

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 - crossover events can occur at homologous regions of non homologous chromosomes

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

Drosophila grows an eye on its wing. This mutant strain is expressing a transcription factor incorrectly. This transcription factor, which is normally expressed in the primordial eye tissue, is now misexpressed in the primordial wing tissue. If this is true, which of the following types of genetic change would most likely lead to this situation? (A) a mutation within the transcription factor gene that leads to a premature stop codon after the 3rd amino acid (B) a mutation within the transcription factor that leads to a substitution of a positively charged amino acid for a negatively charged amino acid (C) a mutation within an upstream enhancer gene (D) a mutation in the TATA box of the gene

C

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

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 - It can produce several different mRNA transcripts from a single gene, and these transcripts can be translated into several different but related proteins.

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 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.

(c) About 1.5% of the human genome codes for exons.

Phenotypic changes: 1. A protein normally localized in the nucleus is now localized in the cytoplasm. _________ 2. A protein acquires a DNA binding domain. _________ 3. Tandem copies of a gene are found in the genome. _________ 4. A copy of a bacterial gene is now found integrated on a human chromosome. _________ 5. A protein becomes much more unstable. _________ 6. A protein normally expressed only in the liver is now expressed in blood cells. ________ Types of genetic change: A.mutation within a gene B.gene duplication C.mutation in a regulatory region D.exon shuffling E.horizontal gene transfer

1. A protein normally localized in the nucleus is now localized in the cytoplasm. ____A____ 2. A protein acquires a DNA binding domain. ____D_____ 3. Tandem copies of a gene are found in the genome. ____B_____ 4. A copy of a bacterial gene is now found integrated on a human chromosome. ____E_____ 5. A protein becomes much more unstable. _____A____ 6. A protein normally expressed only in the liver is now expressed in blood cells. ____C____

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

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 are correct

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.

D - rRNA is highly conserved among all domains

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 purifying selection exon shuffling single nucleotide polymorphisms (SNPs) gene duplication synteny horizontal gene transfer unequal crossing over

Most variation between individual humans is in the form of _SNPs_._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 _Purifying selection_ 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 intron common neutral deleterious somatic gamete unequal homologous zygote

Sexual reproduction in a multicellular organism involves specialized reproductive cells, called __Gamete_s, 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.