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15.6: Chapter 6 exercises

  • Page ID
    31882
  • Multiple Choice

    Frederick Griffith infected mice with a combination of dead R and live S bacterial strains. What was the outcome, and why did it occur?

    A. The mice will live. Transformation was not required.
    B. The mice will die. Transformation of genetic material from R to S was required.
    C. The mice will live. Transformation of genetic material from S to R was required.
    D. The mice will die. Transformation was not required.

    Why was the alga Acetabularia a good model organism for Joachim Hämmerling to use to identify the location of genetic material?

    A. It lacks a nuclear membrane.
    B. It self-fertilizes.
    C. It is a large, asymmetrical, single cell easy to see with the naked eye.
    D. It makes a protein capsid.

    Which of the following best describes the results from Hershey and Chase’s experiment using bacterial viruses with 35S-labeled proteins or 32P-labeled DNA that are consistent with protein being the molecule responsible for hereditary?

    A. After infection with the 35S-labeled viruses and centrifugation, only the pellet would be radioactive.
    B. After infection with the 35S-labeled viruses and centrifugation, both the pellet and the supernatant would be radioactive.
    C. After infection with the 32P-labeled viruses and centrifugation, only the pellet would be radioactive.
    D. After infection with the 32P-labeled viruses and centrifugation, both the pellet and the supernatant would be radioactive.

    Which method did Morgan and colleagues use to show that hereditary information was carried on chromosomes?

    A. statistical predictions of the outcomes of crosses using true-breeding parents
    B. correlations between microscopic observations of chromosomal movement and the characteristics of offspring
    C. transformation of nonpathogenic bacteria to pathogenic bacteria
    D. mutations resulting in distinct defects in metabolic enzymatic pathways

    According to Beadle and Tatum’s “one gene–one enzyme” hypothesis, which of the following enzymes will eliminate the transformation of hereditary material from pathogenic bacteria to nonpathogenic bacteria?

    A. carbohydrate-degrading enzymes
    B. proteinases
    C. ribonucleases
    D. deoxyribonucleases

    Fill in the Blank

    The element ____________ is unique to nucleic acids compared with other macromolecules.

    In the late 1800s and early 1900s, the macromolecule thought to be responsible for heredity was ______________.

    Short Answer

    Why do bacteria and viruses make good model systems for various genetic studies?

    Why was nucleic acid disregarded for so long as the molecule responsible for the transmission of hereditary information?

    Bacteriophages inject their genetic material into host cells, whereas animal viruses enter host cells completely. Why was it important to use a bacteriophage in the Hershey–Chase experiment rather than an animal virus?

    Critical Thinking

    Why are Hershey and Chase credited with identifying DNA as the carrier of heredity even though DNA had been discovered many years before?

    Multiple Choice

    Which of the following is not found within DNA?

    A. thymine
    B. phosphodiester bonds
    C. complementary base pairing
    D. amino acids

    If 30% of the bases within a DNA molecule are adenine, what is the percentage of thymine?

    A. 20%
    B. 25%
    C. 30%
    D. 35%

    Which of the following statements about base pairing in DNA is incorrect?

    A. Purines always base pairs with pyrimidines.
    B. Adenine binds to guanine.
    C. Base pairs are stabilized by hydrogen bonds.
    D. Base pairing occurs at the interior of the double helix.

    If a DNA strand contains the sequence 5ʹ-ATTCCGGATCGA-3ʹ, which of the following is the sequence of the complementary strand of DNA?

    A. 5ʹ-TAAGGCCTAGCT-3ʹ
    B. 5ʹ-ATTCCGGATCGA-3ʹ
    C. 3ʹ-TAACCGGTACGT-5ʹ
    D. 5ʹ-TCGATCCGGAAT-3ʹ

    During denaturation of DNA, which of the following happens?

    A. Hydrogen bonds between complementary bases break.
    B. Phosphodiester bonds break within the sugar-phosphate backbone.
    C. Hydrogen bonds within the sugar-phosphate backbone break.
    D. Phosphodiester bonds between complementary bases break.

    Fill in the Blank

    The end of a nucleic acid strand with a free phosphate group is called the ________.

    True/False

    The work of Rosalind Franklin and R.G. Gosling was important in demonstrating the helical nature of DNA.

    The A-T base pair has more hydrogen bonding than the C-G base pair.

    Short Answer

    What is the role of phosphodiester bonds within the sugar-phosphate backbone of DNA?

    What is meant by the term “antiparallel?”

    Why is DNA with a high GC content more difficult to denature than that with a low GC content?

    Critical Thinking

    A certain DNA sample is found to have a makeup consisting of 22% thymine. Use Chargaff’s rules to fill in the percentages for the other three nitrogenous bases.

    A DNA strand has 22% thymine. The percentages for adenine, guanine, and cytosine are blank.

    In considering the structure of the DNA double helix, how would you expect the structure to differ if there was base pairing between two purines? Between two pyrimidines?

    Multiple Choice

    Which of the following is the enzyme that replaces the RNA nucleotides in a primer with DNA nucleotides?

    A. DNA polymerase III
    B. DNA polymerase I
    C. primase
    D. helicase

    Which of the following is not involved in the initiation of replication?

    A. ligase
    B. DNA gyrase
    C. single-stranded binding protein
    D. primase

    Which of the following enzymes involved in DNA replication is unique to eukaryotes?

    A. helicase
    B. DNA polymerase
    C. ligase
    D. telomerase

    Which of the following would be synthesized using 5′-CAGTTCGGA-3′ as a template?

    A. 3′-AGGCTTGAC-4′
    B. 3′-TCCGAACTG-5′
    C. 3′-GTCAAGCCT-5′
    D. 3′-CAGTTCGGA-5′

    Fill in the Blank

    The enzyme responsible for relaxing supercoiled DNA to allow for the initiation of replication is called ________.

    True/False

    More primers are used in lagging strand synthesis than in leading strand synthesis.

    Short Answer

    Why is primase required for DNA replication?

    What is the role of single-stranded binding protein in DNA replication?

    Below is a DNA sequence. Envision that this is a section of a DNA molecule that has separated in preparation for replication, so you are only seeing one DNA strand. Construct the complementary DNA sequence (indicating 5’ and 3’ ends).

    DNA sequence: 3’-T A C T G A C T G A C G A T C-5’

    Critical Thinking

    Review Figure and Figure. Why was it important that Meselson and Stahl continue their experiment to at least two rounds of replication after isotopic labeling of the starting DNA with 15N, instead of stopping the experiment after only one round of replication?

    If deoxyribonucleotides that lack the 3’-OH groups are added during the replication process, what do you expect will occur?

    Multiple Choice

    Which of the following types of RNA codes for a protein?

    A. dsRNA
    B. mRNA
    C. rRNA
    D. tRNA

    A nucleic acid is purified from a mixture. The molecules are relatively small, contain uracil, and most are covalently bound to an amino acid. Which of the following was purified?

    A. DNA
    B. mRNA
    C. rRNA
    D. tRNA

    Which of the following types of RNA is known for its catalytic abilities?

    A. dsRNA
    B. mRNA
    C. rRNA
    D. tRNA

    Ribosomes are composed of rRNA and what other component?

    1. protein
    2. polypeptides
    3. DNA
    4. mRNA

    Which of the following may use RNA as its genome?

    1. a bacterium
    2. an archaeon
    3. a virus
    4. a eukaryote

    Matching

    Match the correct molecule with its description:

    ___tRNA ___rRNA ___mRNA A. is a major component of ribosome B. is a copy of the information in a gene C. carries an amino acid to the ribosome

    True/False

    Ribosomes are composed mostly of RNA.

    Double-stranded RNA is commonly found inside cells.

    Short Answer

    What are the differences between DNA nucleotides and RNA nucleotides?

    How is the information stored within the base sequence of DNA used to determine a cell’s properties?

    How do complementary base pairs contribute to intramolecular base pairing within an RNA molecule?

    If an antisense RNA has the sequence 5ʹAUUCGAAUGC3ʹ, what is the sequence of the mRNA to which it will bind? Be sure to label the 5ʹ and 3ʹ ends of the molecule you draw.

    Why does double-stranded RNA (dsRNA) stimulate RNA interference?

    Critical Thinking

    Identify the location of mRNA, rRNA, and tRNA in the figure.

    A long strand is labeled ii. A small oval is attached to the bottom of this strand; and a large dome to the top. These two structures together are labeled iii. Smaller rectangles sit inside the large dome and are attached to small segments of the long strand. These rectangles are labeled i.

    Why does it make sense that tRNA and rRNA molecules are more stable than mRNA molecules?

    Multiple Choice

    DNA does all but which of the following?

    A. serves as the genetic material passed from parent to offspring
    B. remains constant despite changes in environmental conditions
    C. provides the instructions for the synthesis of messenger RNA
    D. is read by ribosomes during the process of translation

    According to the central dogma, which of the following represents the flow of genetic information in cells?

    A. protein to DNA to RNA
    B. DNA to RNA to protein
    C. RNA to DNA to protein
    D. DNA to protein to RNA

    True/False

    Cells are always producing proteins from every gene they possess.

    Fill in the Blank

    The process of making an RNA copy of a gene is called ________.

    A cell’s ________ remains constant whereas its phenotype changes in response to environmental influences.

    Short Answer

    Can two observably different cells have the same genotype? Explain.

    Critical Thinking

    A pure culture of an unknown bacterium was streaked onto plates of a variety of media. You notice that the colony morphology is strikingly different on plates of minimal media with glucose compared to that seen on trypticase soy agar plates. How can you explain these differences in colony morphology?

    Multiple Choice

    Which of the following components is involved in the initiation of transcription?

    A. primer
    B. origin
    C. promoter
    D. start codon

    Which of the following is not a function of the 5’ cap and 3’ poly-A tail of a mature eukaryotic mRNA molecule?

    A. to facilitate splicing
    B. to prevent mRNA degradation
    C. to aid export of the mature transcript to the cytoplasm
    D. to aid ribosome binding to the transcript

    Mature mRNA from a eukaryote would contain each of these features except which of the following?

    A. exon-encoded RNA
    B. intron-encoded RNA
    C. 5’ cap
    D. 3’ poly-A tail

    Fill in the Blank

    A ________ mRNA is one that codes for multiple polypeptides.

    The protein complex responsible for removing intron-encoded RNA sequences from primary transcripts in eukaryotes is called the ________.

    Short Answer

    What is the purpose of RNA processing in eukaryotes? Why don’t prokaryotes require similar processing?

    Below is a DNA sequence. Envision that this is a section of a DNA molecule that has separated in preparation for transcription, so you are only seeing the antisense strand. Construct the mRNA sequence transcribed from this template.

    Antisense DNA strand: 3’-T A C T G A C T G A C G A T C-5’

    Critical Thinking

    Predict the effect of an alteration in the sequence of nucleotides in the –35 region of a bacterial promoter.

    Multiple Choice

    Which of the following is the name of the three-base sequence in the mRNA that binds to a tRNA molecule?

    A. P site
    B. codon
    C. anticodon
    D. CCA binding site

    Which component is the last to join the initiation complex during the initiation of translation?

    A. the mRNA molecule
    B. the small ribosomal subunit
    C. the large ribosomal subunit
    D. the initiator tRNA

    During elongation in translation, to which ribosomal site does an incoming charged tRNA molecule bind?

    A. A site
    B. P site
    C. E site
    D. B site

    Which of the following is the amino acid that appears at the N-terminus of all newly translated prokaryotic and eukaryotic polypeptides?

    A. tryptophan
    B. methionine
    C. selenocysteine
    D. glycine

    When the ribosome reaches a nonsense codon, which of the following occurs?

    A. a methionine is incorporated
    B. the polypeptide is released
    C. a peptide bond forms
    D. the A site binds to a charged tRNA

    Fill in the Blank

    The third position within a codon, in which changes often result in the incorporation of the same amino acid into the growing polypeptide, is called the ________.

    The enzyme that adds an amino acid to a tRNA molecule is called ________.

    True/False

    Each codon within the genetic code encodes a different amino acid.

    Short Answer

    Why does translation terminate when the ribosome reaches a stop codon? What happens?

    How does the process of translation differ between prokaryotes and eukaryotes?

    What is meant by the genetic code being nearly universal?

    Below is an antisense DNA sequence. Translate the mRNA molecule synthesized using the genetic code, recording the resulting amino acid sequence, indicating the N and C termini.

    Antisense DNA strand: 3’-T A C T G A C T G A C G A T C-5’

    Critical Thinking

    Label the following in the figure: ribosomal E, P, and A sites; mRNA; codons; anticodons; growing polypeptide; incoming amino acid; direction of translocation; small ribosomal unit; large ribosomal unit.

    A long line at the bottom has many letters on it and is labeled G. Each set of 3 letters is circles and labeled D. Attached to this is a large dome (I) and a small oval (3). Attached to one group of 3 letters is a rectangle 9labeled C); the 3 letters at the bottom of the rectangle are labeled H. A circle at the end of the rectangle is labeled B. The rectangle in the center of the dome labeled I has a long chain of circles attached to it labeled A. An arrow at the bottom points to the right and is labeled F.

    Prior to the elucidation of the genetic code, prominent scientists, including Francis Crick, had predicted that each mRNA codon, coding for one of the 20 amino acids, needed to be at least three nucleotides long. Why is it not possible for codons to be any shorter?

    Multiple Choice

    Which of the following is a change in the sequence that leads to formation of a stop codon?

    A. missense mutation
    B. nonsense mutation
    C. silent mutation
    D. deletion mutation

    The formation of pyrimidine dimers results from which of the following?

    A. spontaneous errors by DNA polymerase
    B. exposure to gamma radiation
    C. exposure to ultraviolet radiation
    D. exposure to intercalating agents

    Which of the following is an example of a frameshift mutation?

    A. a deletion of a codon
    B. missense mutation
    C. silent mutation
    D. deletion of one nucleotide

    Which of the following is the type of DNA repair in which thymine dimers are directly broken down by the enzyme photolyase?

    A. direct repair
    B. nucleotide excision repair
    C. mismatch repair
    D. proofreading

    Which of the following regarding the Ames test is true?

    A. It is used to identify newly formed auxotrophic mutants.
    B. It is used to identify mutants with restored biosynthetic activity.
    C. It is used to identify spontaneous mutants.
    D. It is used to identify mutants lacking photoreactivation activity.

    Fill in the Blank

    A chemical mutagen that is structurally similar to a nucleotide but has different base-pairing rules is called a ________.

    The enzyme used in light repair to split thymine dimers is called ________.

    The phenotype of an organism that is most commonly observed in nature is called the ________.

    True/False

    Carcinogens are typically mutagenic.

    Short Answer

    Why is it more likely that insertions or deletions will be more detrimental to a cell than point mutations?

    Critical Thinking

    Below are several DNA sequences that are mutated compared with the wild-type sequence: 3’-T A C T G A C T G A C G A T C-5’. Envision that each is a section of a DNA molecule that has separated in preparation for transcription, so you are only seeing the template strand. Construct the complementary DNA sequences (indicating 5’ and 3’ ends) for each mutated DNA sequence, then transcribe (indicating 5’ and 3’ ends) the template strands, and translate the mRNA molecules using the genetic code, recording the resulting amino acid sequence (indicating the N and C termini). What type of mutation is each?

    Mutated DNA Template Strand #1: 3’-T A C T G T C T G A C G A T C-5’ Complementary DNA sequence: mRNA sequence transcribed from template: Amino acid sequence of peptide: Type of mutation:
    Mutated DNA Template Strand #2: 3’-T A C G G A C T G A C G A T C-5’ Complementary DNA sequence: mRNA sequence transcribed from template: Amino acid sequence of peptide: Type of mutation:
    Mutated DNA Template Strand #3: 3’-T A C T G A C T G A C T A T C-5’ Complementary DNA sequence: mRNA sequence transcribed from template: Amino acid sequence of peptide: Type of mutation:
    Mutated DNA Template Strand #4: 3’-T A C G A C T G A C T A T C-5’ Complementary DNA sequence: mRNA sequence transcribed from template: Amino acid sequence of peptide: Type of mutation:

    Why do you think the Ames test is preferable to the use of animal models to screen chemical compounds for mutagenicity?

    Multiple Choice

    Which is the mechanism by which improper excision of a prophage from a bacterial chromosome results in packaging of bacterial genes near the integration site into a phage head?

    A. conjugation
    B. generalized transduction
    C. specialized transduction
    D. transformation

    Which of the following refers to the uptake of naked DNA from the surrounding environment?

    A. conjugation
    B. generalized transduction
    C. specialized transduction
    D. transformation

    The F plasmid is involved in which of the following processes?

    A. conjugation
    B. transduction
    C. transposition
    D. transformation

    Which of the following refers to the mechanism of horizontal gene transfer naturally responsible for the spread of antibiotic resistance genes within a bacterial population?

    A. conjugation
    B. generalized transduction
    C. specialized transduction
    D. transformation

    Fill in the Blank

    A small DNA molecule that has the ability to independently excise from one location in a larger DNA molecule and integrate into the DNA elsewhere is called a ________.

    ________ is a group of mechanisms that allow for the introduction of genetic material from one organism to another organism within the same generation.

    True/False

    Asexually reproducing organisms lack mechanisms for generating genetic diversity within a population.

    Short Answer

    Briefly describe two ways in which chromosomal DNA from a donor cell may be transferred to a recipient cell during the process of conjugation.

    Describe what happens when a nonsense mutation is introduced into the gene encoding transposase within a transposon.

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