Biology Chapter 2: Protein Production
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Questions and Answers

What is the ultimate purpose of THF synthesis in the bacterial cell?

  • Cell wall formation
  • Energy production
  • Protein synthesis
  • Deoxynucleotide synthesis (correct)

    • Why is the THF synthesis pathway a target for antimicrobial compounds?

  • It is involved in energy production
  • It is unique to bacterial cells (correct)
  • It is essential for human cells
  • It is not targeted by the immune system

    • What is the primary function of the enzyme DNA polymerase?

  • Breaking down proteins
  • Replicating the bacterial chromosome (correct)
  • Synthesizing THF
  • Regulating supercoiling of DNA

    • What is the result of twisting one end of DNA while holding the other end fixed?

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

    What is the normal number of nucleotide pairs per helical turn in relaxed DNA?

    <p>10</p> Signup and view all the answers

    What is the purpose of topoisomerases?

    <p>Regulating supercoiling of DNA</p> Signup and view all the answers

    What is the rate of mRNA synthesis by bacterial RNA polymerase under ideal conditions?

    <p>55 nucleotides per second</p> Signup and view all the answers

    What is the main difference between bacterial and eukaryotic RNA polymerase in terms of transcription initiation?

    <p>Eukaryotic RNA polymerase requires additional transcription factors</p> Signup and view all the answers

    What is the consequence of having a chromosome composed of helical DNA?

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

    What is the result of increasing or decreasing the number of nucleotide pairs per helical turn?

    <p>Additional stress on the DNA molecule</p> Signup and view all the answers

    What is the structural characteristic of bacterial RNA polymerase?

    <p>It consists of five subunits</p> Signup and view all the answers

    What is the significance of the differences between bacterial and eukaryotic RNA polymerase?

    <p>They make the enzyme complex an ideal target for antimicrobial compounds</p> Signup and view all the answers

    What is the role of RNA polymerase in the cell?

    <p>To transcribe mRNA from DNA</p> Signup and view all the answers

    What is the characteristic of eukaryotic RNA polymerase in terms of its size?

    <p>It is larger than bacterial RNA polymerase</p> Signup and view all the answers

    What is the enzyme complex responsible for transcribing DNA into RNA in bacterial cells?

    <p>RNA polymerase</p> Signup and view all the answers

    What is the name of the RNA molecule synthesized during the transcription process?

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

    What is the source of energy used to power the transcription process?

    <p>Nucleoside triphosphates</p> Signup and view all the answers

    What is the process by which the information in the DNA of a bacterial gene is used to synthesize an RNA molecule?

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

    What is the role of RNA polymerase in bacterial cells?

    <p>To synthesize mRNA</p> Signup and view all the answers

    What is the result of the transcription process in bacterial cells?

    <p>An mRNA molecule is synthesized</p> Signup and view all the answers

    What is the relationship between the DNA molecule and the mRNA molecule in bacterial cells?

    <p>The mRNA molecule is synthesized from the DNA molecule</p> Signup and view all the answers

    What is the purpose of the proton motive force in bacterial cells?

    <p>To transport nutrients into the cell</p> Signup and view all the answers

    What is the name of the enzyme complex responsible for transcribing DNA into RNA in bacterial cells?

    <p>RNA polymerase</p> Signup and view all the answers

    What is the process by which the information in the DNA of a bacterial gene is used to synthesize an RNA molecule?

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

    What is the name of the RNA molecule synthesized during the transcription process?

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

    What is the energy source used to power the transcription process?

    <p>Proton motive force</p> Signup and view all the answers

    What is the role of RNA polymerase in the transcription process?

    <p>To synthesize RNA from DNA</p> Signup and view all the answers

    What is the result of the transcription process in bacterial cells?

    <p>Synthesis of RNA</p> Signup and view all the answers

    What is the relationship between the DNA molecule and the mRNA molecule in bacterial cells?

    <p>mRNA is synthesized from DNA</p> Signup and view all the answers

    What is the purpose of the proton motive force in bacterial cells?

    <p>To power important cellular processes</p> Signup and view all the answers

    What is the function of RNA polymerase in the cell?

    <p>To transcribe DNA into RNA</p> Signup and view all the answers

    What is the rate of mRNA synthesis by bacterial RNA polymerase under ideal conditions?

    <p>55 nucleotides per second</p> Signup and view all the answers

    What is a key difference between bacterial and eukaryotic RNA polymerase?

    <p>Bacterial RNA polymerase requires the help of additional transcription factors</p> Signup and view all the answers

    What is the structural characteristic of bacterial RNA polymerase?

    <p>It has five subunits</p> Signup and view all the answers

    Why is RNA polymerase an ideal target for antimicrobial compounds?

    <p>Because it is essential for bacterial growth</p> Signup and view all the answers

    What is the size of bacterial RNA polymerase?

    <p>90 × 90 × 160 angstroms</p> Signup and view all the answers

    What is the precursor of THF that humans readily absorb from their diet?

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

    What is the enzyme responsible for replicating the bacterial chromosome?

    <p>DNA polymerase</p> Signup and view all the answers

    What is the consequence of twisting one end of DNA while holding the other end fixed?

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

    What is the normal number of nucleotide pairs per helical turn in relaxed DNA?

    <p>10</p> Signup and view all the answers

    What is the function of topoisomerases?

    <p>To regulate supercoiling of DNA</p> Signup and view all the answers

    What is the result of increasing or decreasing the number of nucleotide pairs per helical turn?

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

    What is the role of dihydropteroate synthase in bacterial cells?

    <p>To synthesize THF</p> Signup and view all the answers

    What is the consequence of having a chromosome composed of helical DNA?

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

    What is unique about the size of glycopeptide antibiotics?

    <p>They are extremely large peptides.</p> Signup and view all the answers

    Why are glycopeptide antibiotics often given intravenously?

    <p>They are poorly absorbed in the gastrointestinal tract.</p> Signup and view all the answers

    What type of organisms are glycopeptide antibiotics most effective against?

    <p>Gram-positive bacteria</p> Signup and view all the answers

    Which of the following is a limitation of glycopeptide antibiotics?

    <p>They are not effective against gram-negative bacteria.</p> Signup and view all the answers

    What is the coverage of vancomycin and telavancin against staphylococci and streptococci?

    <p>Nearly universal coverage against staphylococci and streptococci.</p> Signup and view all the answers

    Why should vancomycin not be used to treat L. monocytogenes infections?

    <p>Clinical failures have been reported with vancomycin.</p> Signup and view all the answers

    What type of bacteria is colistin effective against?

    <p>Aerobic gram-negative bacteria</p> Signup and view all the answers

    What is a side effect of colistin toxicity?

    <p>Both A and B</p> Signup and view all the answers

    What is the mechanism of action of colistin?

    <p>Binds to and disrupts the bacterial outer membrane</p> Signup and view all the answers

    Why was colistin not used frequently in the past?

    <p>It was toxic</p> Signup and view all the answers

    What type of bacteria is colistin not effective against?

    <p>Proteus spp.</p> Signup and view all the answers

    What is the primary use of colistin?

    <p>Treatment of bacterial infections</p> Signup and view all the answers

    What is a characteristic of colistin?

    <p>It lacks activity against Proteus spp.</p> Signup and view all the answers

    What is the significance of colistin?

    <p>It is useful in the treatment of infections caused by aerobic gram-negative bacteria</p> Signup and view all the answers

    What type of lactone ring does clarithromycin consist of?

    <p>14-member macrocyclic lactone ring</p> Signup and view all the answers

    What type of bacteria is clarithromycin active against?

    <p>Both gram-positive and gram-negative bacteria</p> Signup and view all the answers

    Which of the following bacteria is clarithromycin active against?

    <p>Haemophilus influenzae</p> Signup and view all the answers

    What type of organisms is clarithromycin active against, in addition to bacteria?

    <p>Atypical bacteria and spirochetes</p> Signup and view all the answers

    Which of the following is NOT a type of bacteria that clarithromycin is active against?

    <p>Escherichia coli</p> Signup and view all the answers

    What is the advantage of clarithromycin compared to erythromycin?

    <p>It has somewhat greater activity against aerobic gram-positive bacteria and H. influenzae</p> Signup and view all the answers

    What is the type of lactone ring that erythromycin consists of?

    <p>14-member macrocyclic lactone ring</p> Signup and view all the answers

    What is the class of antibiotics that clarithromycin belongs to?

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

    What class of antibiotics does tigecycline belong to?

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

    What is the characteristic of tigecycline?

    <p>Broad-spectrum antibiotic</p> Signup and view all the answers

    Which of the following bacteria is susceptible to tigecycline?

    <p>Streptococcus pyogenes</p> Signup and view all the answers

    What type of bacteria is Haemophilus influenzae?

    <p>Gram-negative</p> Signup and view all the answers

    Which of the following is NOT susceptible to tigecycline?

    <p>Mycobacterium tuberculosis</p> Signup and view all the answers

    What type of bacteria is Listeria monocytogenes?

    <p>Gram-positive</p> Signup and view all the answers

    Which of the following is an anaerobic bacterium susceptible to tigecycline?

    <p>Bacteroides fragilis</p> Signup and view all the answers

    What is the characteristic of tigecycline compared to other antibiotics?

    <p>Broader spectrum of activity</p> Signup and view all the answers

    What is a potential consequence of using clindamycin?

    <p>Life-threatening colitis</p> Signup and view all the answers

    What is the origin of the name 'lincosamide antibiotics'?

    <p>From the site where the bacterium was isolated</p> Signup and view all the answers

    What is the significance of Streptomyces spp.?

    <p>They are bacteria that produce antibiotics</p> Signup and view all the answers

    What is a characteristic of clindamycin?

    <p>It is active against anaerobic bacteria</p> Signup and view all the answers

    What is a potential consequence of resistance to clindamycin?

    <p>Resistance to other antibiotics</p> Signup and view all the answers

    What is the name of the antibiotic that was first isolated from a bacterium found in Lincoln, Nebraska?

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

    What is the significance of the study by Falagas et al. (1995)?

    <p>It compared the efficacy of clindamycin and metronidazole</p> Signup and view all the answers

    What is the name of the bacterium that produces lincomycin?

    <p>Streptomyces spp.</p> Signup and view all the answers

    Study Notes

    Protein Production

    • Protein production in bacteria involves DNA transcription and translation, resulting in the creation of a protein.
    • Energy from fuel consumption is harnessed and stored in nucleoside triphosphates and the proton motive force, which powers important processes like active transport and ATP generation.

    Transcription

    • Transcription is the process by which DNA information is used to synthesize messenger RNA (mRNA).
    • RNA polymerase binds to DNA and uses it as a template to add ribonucleic acids to a corresponding mRNA molecule.
    • Bacterial RNA polymerase is distinct from eukaryotic RNA polymerase, with differences in structure and function.
    • Bacterial RNA polymerase can make mRNA at a rate of 55 nucleotides per second.

    RNA Polymerase

    • Bacterial RNA polymerase consists of five subunits and has dimensions of approximately 90 × 90 × 160 angstroms.
    • Eukaryotic RNA polymerase has many more subunits and has dimensions of 140 × 136 × 110 angstroms.
    • Bacterial RNA polymerase can initiate transcription alone, whereas eukaryotic RNA polymerase requires additional transcription factors.

    Tetrahydrofolate (THF) Synthesis

    • THF is required for the synthesis of several nucleotides.
    • Humans can absorb folate, a precursor of THF, from their diet, but most bacteria cannot and must synthesize it.
    • The synthetic pathway of THF is an attractive target for antimicrobial compounds.

    DNA Synthetic Enzymes

    • DNA polymerase is responsible for replicating the bacterial chromosome, but other enzymes are also required.
    • Topoisomerases regulate supercoiling, or twisting of the DNA, to accommodate the stress on the DNA molecule.
    • Supercoiling results in the formation of additional nucleotide pairs per helical turn, which is accommodated by the formation of supercoils.

    Protein Production

    • Protein production in bacteria involves DNA transcription and translation, resulting in the creation of a protein.
    • Energy from fuel consumption is harnessed and stored in nucleoside triphosphates and the proton motive force, which powers important processes like active transport and ATP generation.

    Transcription

    • Transcription is the process by which DNA information is used to synthesize messenger RNA (mRNA).
    • RNA polymerase binds to DNA and uses it as a template to add ribonucleic acids to a corresponding mRNA molecule.
    • Bacterial RNA polymerase is distinct from eukaryotic RNA polymerase, with differences in structure and function.
    • Bacterial RNA polymerase can make mRNA at a rate of 55 nucleotides per second.

    RNA Polymerase

    • Bacterial RNA polymerase consists of five subunits and has dimensions of approximately 90 × 90 × 160 angstroms.
    • Eukaryotic RNA polymerase has many more subunits and has dimensions of 140 × 136 × 110 angstroms.
    • Bacterial RNA polymerase can initiate transcription alone, whereas eukaryotic RNA polymerase requires additional transcription factors.

    Tetrahydrofolate (THF) Synthesis

    • THF is required for the synthesis of several nucleotides.
    • Humans can absorb folate, a precursor of THF, from their diet, but most bacteria cannot and must synthesize it.
    • The synthetic pathway of THF is an attractive target for antimicrobial compounds.

    DNA Synthetic Enzymes

    • DNA polymerase is responsible for replicating the bacterial chromosome, but other enzymes are also required.
    • Topoisomerases regulate supercoiling, or twisting of the DNA, to accommodate the stress on the DNA molecule.
    • Supercoiling results in the formation of additional nucleotide pairs per helical turn, which is accommodated by the formation of supercoils.

    Glycopeptide Antibiotics

    • Glycopeptide antibiotics are peptides with sugar moieties attached to them.
    • Examples of glycopeptide antibiotics include vancomycin and telavancin.
    • These antibiotics are poorly absorbed in the gastrointestinal tract and must be given intravenously to treat systemic infections.
    • They are extremely large and unable to pass through porins in the outer membranes of gram-negative bacteria, restricting their activity to gram-positive organisms.
    • Vancomycin and telavancin are active against nearly all staphylococci and streptococci, including methicillin-resistant staphylococci and strains of penicillin-resistant S. pneumoniae.
    • Susceptibility among enterococci is now variable.

    Colistin

    • Colistin has activity against many aerobic gram-negative bacteria, including P. aeruginosa, E. coli, and Klebsiella spp.
    • Many multidrug-resistant strains of these bacteria remain susceptible to colistin.
    • Colistin lacks activity against other gram-negative bacteria, gram-positive bacteria, and anaerobic bacteria.
    • The toxicity of colistin has been found to be less than previously believed, but it is still associated with nephrotoxicity and neurotoxicity.

    Macrolides

    • Macrolides are active against gram-positive bacteria, including some Streptococcus pyogenes, viridans streptococci, and Staphylococcus aureus.
    • They are also active against gram-negative bacteria, including Neisseria spp. and Haemophilus influenzae.
    • Macrolides are active against atypical bacteria, including Chlamydia spp., Mycoplasma spp., and Legionella pneumophila.
    • Clarithromycin is a semisynthetic derivative of erythromycin with greater activity against aerobic gram-positive bacteria and H. influenzae.

    Tigecycline

    • Tigecycline is a glycylcycline antibiotic with broad activity against aerobic and anaerobic bacteria.
    • It is active against gram-positive bacteria, including Streptococcus pyogenes, viridans group streptococci, and Staphylococcus aureus.
    • Tigecycline is also active against gram-negative bacteria, including Haemophilus influenzae and Neisseria spp.
    • It is active against atypical bacteria, including Mycoplasma spp.
    • Caution must be exercised regarding the relatively frequent occurrence of C. difficile colitis associated with its use.

    Clindamycin

    • Clindamycin is active against many aerobic and anaerobic bacteria.
    • Resistance to erythromycin may also lead to resistance to clindamycin in some bacteria.
    • Use of clindamycin may lead to life-threatening C. difficile colitis.

    Lincosamide Antibiotics

    • The class of lincosamide antibiotics received its name from the site where the bacterium that produced lincomycin was isolated: Lincoln, Nebraska.
    • Lincomycin is a new antibiotic with biologic properties.

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    This quiz covers the basics of protein production, including DNA transcription, RNA, and ribonucleic acids. Test your understanding of the biological processes involved.

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