Lodish Ch 5: Molecular Biology: Nucleic Acids
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Questions and Answers

In biology the central dogma refers to:

  • RNA to protein to DNA.
  • protein to DNA to RNA.
  • DNA to RNA to protein. (correct)
  • RNA to DNA to protein.

    • There are four basic molecular processes in a cell, three of which lead to the production of protein. Which of the following shows the correct order?

  • translation, RNA processing, transcription
  • transcription, RNA processing, translation (correct)
  • RNA processing, translation, transcription
  • transcription, translation, RNA processing

    • Nucleotide bases within a single strand of DNA are held together by which of the following bonds?

  • polynucleotide
  • phosphodiester (correct)
  • phosphoester
  • pentose-phosphate

    • In DNA, which of the following base pairing normally occurs between two strands of DNA?

    <p>T to A</p> Signup and view all the answers

    In the laboratory, which of the following two factors are most useful in manipulating DNA?

    <p>temperature and pH</p> Signup and view all the answers

    To study the melting temperature ($T_m$) of your DNA, you have plotted the absorbance of UV light at 260 nm against temperature and have come up with the the following graph. Based on the evidence, the $T_m$ of your double-stranded DNA is approximately:

    <p>80 degrees</p> Signup and view all the answers

    Which of the following is not a constituent of deoxyribonucleotides?

    <p>ribose</p> Signup and view all the answers

    Which base pair(s) typically occur(s) in double-stranded DNA?

    <p>G-C</p> Signup and view all the answers

    When the circular double-stranded DNA of certain viruses is underwound, the DNA can twist back on itself and form:

    <p>supercoils</p> Signup and view all the answers

    The ability of DNA to denature is important for which process?

    <p>all of the above</p> Signup and view all the answers

    The most common arrangement of protein-coding genes in bacteria are those where the genes encoding proteins that work together are arranged in a contiguous array of DNA called:

    <p>an operon.</p> Signup and view all the answers

    Which of the following are removed from mRNAs during processing?

    <p>noncoding sequences</p> Signup and view all the answers

    The base in the wobble position of a codon a. is the 5′ (first) base. b. is the 3' (third) base. c. is the second base. d. often contains adenine.

    <p>is the 3' (third) base.</p> Signup and view all the answers

    Approximately what percent of all human genes are expressed as alternatively spliced mRNAs?

    <p>90</p> Signup and view all the answers

    The genetic code is said to be "degenerate" because:

    <p>a particular amino acid can be specified by more than one codon.</p> Signup and view all the answers

    In eukaryotic cells, protein synthesis in the cytoplasm utilizes three types of RNA molecules. Which of the following contains a three nucleotide sequence called the anticodon?

    <p>tRNA</p> Signup and view all the answers

    In humans, the ribosome responsible for translating proteins consists of which of following two subunits?

    <p>60S and 40S</p> Signup and view all the answers

    Which of the following techniques would you need to use in order to determine the size of the large and small ribosomal subunits in E. coli?

    <p>centrifugation</p> Signup and view all the answers

    The first stage of protein translation occurs when Met-tRNA base pairs with the mRNA being translated in the ribosomal:

    <p>A site.</p> Signup and view all the answers

    Which of the following is seen when a single mRNA is simultaneously translated to form multiple copies of a polypeptide chain?

    <p>polysome</p> Signup and view all the answers

    You are studying polysomes and want to see if their numbers are actually increased in cells translating protein from an expressed retroviral oncogene. Which of the following methods are used to visualize these structures?

    <p>sedimentation analyses and electron microscopy</p> Signup and view all the answers

    Which of the following is not a recognized stage of protein synthesis in either prokaryotes or eukaryotes?

    <p>translation</p> Signup and view all the answers

    Which of the following factors recognizes the UAG, UAA, and UGA codons?

    <p>termination factors</p> Signup and view all the answers

    Which codon serves as the start codon in mRNA for translation?

    <p>AUG</p> Signup and view all the answers

    Which of the following is a protein that is involved in translation?

    <p>aminoacyl-tRNA synthetase</p> Signup and view all the answers

    Which of the following structures interacts with ribosomes?

    <p>all of the above</p> Signup and view all the answers

    Cellular protein synthesis proceeds in which direction?

    <p>amino to carboxyl terminus</p> Signup and view all the answers

    In eukaryotes, the circular structure of mRNA molecules undergoing translation serves to

    <p>increase translation efficiency.</p> Signup and view all the answers

    In which of these polymers are the monomers added one at a time?

    <p>all of the above</p> Signup and view all the answers

    Okazaki fragments are small fragments of DNA that eventually are ligated to form which of the following strands of DNA?

    <p>lagging</p> Signup and view all the answers

    DNA replication begins at sequences called

    <p>origins</p> Signup and view all the answers

    An enzyme that breaks DNA, dispels the tension, and reseals the strand ahead of a DNA replication growing fork is called a(n)

    <p>topoisomerase.</p> Signup and view all the answers

    Silent mutations that occur under a variety of conditions in DNA results in which of the following?

    <p>no change in the amino acid</p> Signup and view all the answers

    Which of the following lead(s) to a point mutation?

    <p>all of the above</p> Signup and view all the answers

    A Holliday structure is a(n)

    <p>intermediate in genetic recombination.</p> Signup and view all the answers

    Which of the following are enzymes that play a key role in the base excision repair of nucleotide mismatches and damaged bases?

    <p>glycosylases</p> Signup and view all the answers

    Thymine-thymine dimers are chemical adducts that develop in the DNA as a result of damage caused by which of the following?

    <p>UV light</p> Signup and view all the answers

    Viruses that use the lytic cycle of growth generally proceed through five general stages. Which one of the following shows the correct order of three of these stages?

    <p>replication, assembly, release</p> Signup and view all the answers

    You have received a saliva sample from a group of veterinarians who think one of the dogs they are treating has rabies. Which of the following techniques would you use to determine not only if this sample contains viral particles, but how many viral particles are in the sample?

    <p>plaque assay</p> Signup and view all the answers

    This type of assay can be used to count the number of viral particles in a sample.

    <p>plaque assay</p> Signup and view all the answers

    Study Notes

    Nucleic Acid Structure

    • The central dogma in biology describes the flow of genetic information: DNA to RNA to protein
    • DNA nucleotides are held together by phosphodiester bonds
    • DNA base pairing follows this pattern: Adenine (A) with Thymine (T), and Guanine (G) with Cytosine (C)

    Molecular Processes

    • The four basic molecular processes in a cell include transcription, RNA processing, translation, and, lastly, protein synthesis
    • The correct order is: transcription, RNA processing, and translation

    Nucleotide Composition

    • Deoxyribonucleotides are crucial components of DNA
    • Deoxyribonucleotides include: phosphate moieties, deoxyribose, and organic bases.

    DNA Replication Factors

    • Two important factors in DNA manipulation are magnesium ions and sugar concentrations
    • DNA can twist back on its self to form supercoils when the circular structure is underwound

    DNA Melting Temperature

    • The melting temperature (Tm) of DNA is determined by the amount of G-C base pairs (higher G-C content means higher Tm)

    Other Key Concepts

    • The ability of DNA to denature is important in DNA synthesis and nucleic acid hybridization experiments
    • Operons are common arrangements of genes encoding proteins that function together
    • Non-protein-coding sequences (introns) are removed from RNA during processing
    • The wobble position in codons is typically the third base
    • Human genes are expressed as alternatively spliced mRNAs in approximately 90% of cases
    • A codon is translated into an amino acid to build a protein using tRNA
    • Ribosomes consist of 60S and 40S subunits in humans
    • A polysome is when one mRNA simultaneously translates into many polypeptide chains

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    Lodish 8e Chapter 5 Test Bank PDF

    Description

    Test your knowledge on nucleic acid structure, molecular processes, and factors affecting DNA replication in this comprehensive quiz. Understand the central dogma, nucleotide composition, and the melting temperature of DNA. Perfect for students studying molecular biology.

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