Ribosomal RNA Function and Mechanism of Action
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Questions and Answers

What are the key targets in ribosomal RNA function?

  • 70S ribosomal subunit
  • 60S ribosomal subunit
  • 30S and 50S ribosomal subunits (correct)
  • 80S ribosomal subunit

    • What is the primary function of the 30S subunit in bacterial protein synthesis?

  • Translocating of the translation machine
  • Decoding of mRNA (correct)
  • Binds incoming tRNA containing amino acids
  • Linking together of amino acids

    • What is the primary function of the 50S subunit in bacterial protein synthesis?

  • Translocating of the translation machine
  • Binds incoming tRNA containing amino acids
  • Decoding of mRNA
  • Linking together of amino acids (correct)

    • What is unique about Chloramphenicol as compared to other antibacterial agents?

    <p>It also has activity against protozoan and parasites</p> Signup and view all the answers

    What is the mechanism of action of Fluoroquinolones?

    <p>Inhibition of DNA synthesis</p> Signup and view all the answers

    What is the key structural component of Fluoroquinolones?

    <p>Quinolone structure with Fluorine at position 6</p> Signup and view all the answers

    What is the role of Topoisomerase II (DNA gyrase) in bacterial cells?

    <p>Allows relaxation of supercoiled DNA necessary for normal transcription and replication</p> Signup and view all the answers

    What is the result of inhibiting Topoisomerase II (DNA gyrase) in bacterial cells?

    <p>Prevents DNA replication</p> Signup and view all the answers

    What is the primary function of ATP in the process of DNA segment joining?

    <p>To 'lock' the second DNA segment into place</p> Signup and view all the answers

    What is the primary mechanism of resistance to folic acid antagonists in bacteria?

    <p>Plasmid transfer or random mutations</p> Signup and view all the answers

    What is the effect of PABA analogues on folic acid formation in bacteria?

    <p>They competitively inhibit dihydropteroate synthetase</p> Signup and view all the answers

    What is the primary difference between the mechanism of action of PABA analogues and folate analogues?

    <p>PABA analogues inhibit dihydropteroate synthetase, while folate analogues inhibit dihydrofolate reductase</p> Signup and view all the answers

    What is the result of the second DNA segment passing through the enzyme?

    <p>The coiling of the DNA is changed by one</p> Signup and view all the answers

    What is the general effect of chromosomal mutations in the genes that encode one or both enzymes on antibiotic resistance?

    <p>It confers cross-resistance in class</p> Signup and view all the answers

    In bacterial protein synthesis, which site contains the growing peptide chain?

    <p>P &quot;peptidyl&quot; site</p> Signup and view all the answers

    Which antibacterial agent is an exception in terms of having activity against protozoa and parasites?

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

    What is the result of inhibiting Topoisomerase IV in bacterial cells?

    <p>Prevention of DNA replication</p> Signup and view all the answers

    What is the mechanism of action of Fluoroquinolones in terms of DNA synthesis?

    <p>Changing the configuration of DNA</p> Signup and view all the answers

    What is unique about the mechanism of action of Fluoroquinolones compared to other antibacterial agents?

    <p>They are bactericidal and concentration-dependent</p> Signup and view all the answers

    What is the role of Topoisomerase II (DNA gyrase) in bacterial cells?

    <p>Relaxation of supercoiled DNA</p> Signup and view all the answers

    What is the general effect of inhibiting bacterial protein synthesis?

    <p>Bacteriostatic effect</p> Signup and view all the answers

    What is the common feature among most antibacterial agents that target ribosomal RNA function?

    <p>Selective toxicity against bacteria</p> Signup and view all the answers

    What is the consequence of the second DNA segment passing through the enzyme?

    <p>Changes the coiling of the DNA by 1</p> Signup and view all the answers

    Which alteration leads to antibiotic resistance in bacteria?

    <p>Alteration in the expression of membrane porins</p> Signup and view all the answers

    What is the target of Folate analogues in bacterial cells?

    <p>Dihydrofolate reductase</p> Signup and view all the answers

    What is the result of PABA analogues on folic acid formation in bacterial cells?

    <p>Prevents folic acid formation</p> Signup and view all the answers

    What is the mechanism of action of Sulfonamides?

    <p>Competitively inhibit dihydropteroate synthetase</p> Signup and view all the answers

    What is the consequence of enzyme cutting both strands of the first DNA segment?

    <p>The first DNA segment is nicked</p> Signup and view all the answers

    What is the role of ATP in the process of DNA segment joining?

    <p>To lock the second DNA segment into place</p> Signup and view all the answers

    Which type of mutation can lead to antibiotic resistance in bacteria?

    <p>Chromosomal mutations</p> Signup and view all the answers

    How do PABA analogues prevent folic acid formation in bacteria?

    <p>By competitively inhibiting dihydropteroate synthetase</p> Signup and view all the answers

    What is the effect of the second DNA segment passing through the enzyme?

    <p>It changes the coiling of the DNA by 1</p> Signup and view all the answers

    How do Folate analogues prevent the conversion of dihydrofolate to tetrahydrofolate?

    <p>By competitively inhibiting dihydrofolate reductase</p> Signup and view all the answers

    What is the general effect of alterating the expression of membrane porins on antibiotic resistance?

    <p>It increases the antibiotic resistance</p> Signup and view all the answers

    Which subunit is responsible for decoding of mRNA in bacterial protein synthesis?

    <p>30S</p> Signup and view all the answers

    What is the primary role of Topoisomerase IV in bacterial cells?

    <p>Decatenation of replicated DNA</p> Signup and view all the answers

    What is the result of complete inhibition of protein synthesis in bacteria?

    <p>Bacterial stasis</p> Signup and view all the answers

    What is the key difference between Fluoroquinolones and other antibacterial agents?

    <p>They are concentration-dependent killers</p> Signup and view all the answers

    Which antibacterial agent has activity against both bacteria and protozoa?

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

    What is the result of inhibition of DNA gyrase in bacterial cells?

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

    What is the mechanism by which Fluoroquinolones inhibit DNA synthesis?

    <p>Inhibition of topoisomerase enzymes</p> Signup and view all the answers

    What is the general effect of inhibiting bacterial protein synthesis?

    <p>Bacterial stasis</p> Signup and view all the answers

    What is the role of ATP in the process of DNA segment joining?

    <p>To 'lock' the second DNA segment into place</p> Signup and view all the answers

    What is the mechanism of action of PABA analogues?

    <p>They competitively inhibit dihydropteroate synthetase</p> Signup and view all the answers

    What is a mechanism of resistance to Folic Acid Antagonists?

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

    What is the effect of the second DNA segment passing through the enzyme?

    <p>It changes the coiling of the DNA by 1</p> Signup and view all the answers

    What is the target of Folate analogues?

    <p>Dihydrofolate reductase</p> Signup and view all the answers

    What is a mechanism of resistance to antibiotics?

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

    What is the primary function of the 50S ribosomal subunit in bacterial protein synthesis?

    <p>Linking together of amino acids</p> Signup and view all the answers

    Which of the following antibacterial agents has activity against both bacteria and protozoa?

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

    What is the result of inhibition of Topoisomerase II (DNA gyrase) in bacterial cells?

    <p>Supercoiling of DNA, preventing DNA replication</p> Signup and view all the answers

    What is the primary mechanism of action of Fluoroquinolones?

    <p>Inhibition of DNA synthesis</p> Signup and view all the answers

    What is the common feature among most antibacterial agents that target ribosomal RNA function?

    <p>Selective toxicity against bacteria</p> Signup and view all the answers

    What is the result of complete inhibition of protein synthesis in bacteria?

    <p>Cell growth inhibition</p> Signup and view all the answers

    What is the key difference between Fluoroquinolones and other antibacterial agents?

    <p>Mechanism of action</p> Signup and view all the answers

    Which of the following is a characteristic of Fluoroquinolones?

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

    What is the primary function of the ribosomal RNA in bacterial protein synthesis?

    <p>To provide the machinery for protein synthesis</p> Signup and view all the answers

    What is the role of the P site in bacterial protein synthesis?

    <p>It contains the growing peptide chain</p> Signup and view all the answers

    What is the role of the 30S subunit in bacterial protein synthesis?

    <p>It is involved in decoding of mRNA</p> Signup and view all the answers

    What is the function of the A site in bacterial protein synthesis?

    <p>It binds to incoming tRNA containing amino acids</p> Signup and view all the answers

    What is the role of the 50S subunit in bacterial protein synthesis?

    <p>It is involved in linking of amino acids</p> Signup and view all the answers

    What is the primary function of the ribosomal RNA in bacterial protein synthesis?

    <p>To provide the machinery for protein synthesis</p> Signup and view all the answers

    What is the function of the P site in bacterial protein synthesis?

    <p>To contain the growing peptide chain</p> Signup and view all the answers

    What is the function of the A site in bacterial protein synthesis?

    <p>To bind incoming tRNA containing amino acids</p> Signup and view all the answers

    What is the result of the interaction between the 30S and 50S subunits in bacterial protein synthesis?

    <p>The formation of a translation complex</p> Signup and view all the answers

    What is the role of the 30S subunit in bacterial protein synthesis?

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

    Which antibacterial agent is an exception in terms of having activity against protozoa and parasites?

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

    What is the effect of complete inhibition of protein synthesis in bacteria?

    <p>Bacteria are inhibited from multiplying</p> Signup and view all the answers

    What is a common characteristic of most antibacterial agents that target ribosomal RNA function?

    <p>They are selective to bacteria</p> Signup and view all the answers

    What is the primary mechanism of action of antibacterial agents that target ribosomal RNA function?

    <p>Inhibition of protein synthesis</p> Signup and view all the answers

    Which type of antibacterial agent is an exception in terms of being bactericidal?

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

    What is the significance of the fluorine at position 6 in the quinolone structure of Fluoroquinolones?

    <p>It increases the specificity of Fluoroquinolones for bacterial DNA gyrase</p> Signup and view all the answers

    What type of structural changes can occur in Fluoroquinolones at positions 1, 5, 7, and 8?

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

    What is the consequence of altering the quinolone structure of Fluoroquinolones?

    <p>Loss of antibacterial activity</p> Signup and view all the answers

    What is the role of the quinolone structure in the mechanism of action of Fluoroquinolones?

    <p>It inhibits the activity of DNA gyrase</p> Signup and view all the answers

    How do changes in the quinolone structure of Fluoroquinolones affect their antibacterial activity?

    <p>They alter the spectrum of antibacterial activity</p> Signup and view all the answers

    What is unique about the quinolone structure of Fluoroquinolones?

    <p>Fluorine at position 6</p> Signup and view all the answers

    What structural changes can occur at which positions in Fluoroquinolones?

    <p>Positions 1, 5, 7, and 8</p> Signup and view all the answers

    What is the significance of the quinolone structure of Fluoroquinolones?

    <p>It is responsible for the mechanism of action of Fluoroquinolones</p> Signup and view all the answers

    What is the effect of structural changes at positions 1, 5, 7, and 8 in Fluoroquinolones?

    <p>Decreased antibacterial activity</p> Signup and view all the answers

    What is the relationship between the quinolone structure and the antibacterial activity of Fluoroquinolones?

    <p>The quinolone structure is responsible for the mechanism of action of Fluoroquinolones</p> Signup and view all the answers

    What is the effect of inhibiting DNA synthesis on the DNA's primary sequence?

    <p>It does not change the DNA's primary sequence</p> Signup and view all the answers

    What is the result of inhibiting DNA synthesis on the DNA's configuration?

    <p>A change in the configuration of the DNA</p> Signup and view all the answers

    What is the primary mechanism of action of antibacterial agents that inhibit DNA synthesis?

    <p>Inhibition of DNA synthesis</p> Signup and view all the answers

    What is the consequence of inhibiting DNA synthesis on bacterial growth?

    <p>A decrease in bacterial growth</p> Signup and view all the answers

    What is the target of antibacterial agents that inhibit DNA synthesis?

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

    What is the effect of the inhibition of DNA synthesis on the DNA's primary sequence?

    <p>It does not change the primary sequence</p> Signup and view all the answers

    How does the inhibition of DNA synthesis affect the DNA's configuration?

    <p>It changes the configuration</p> Signup and view all the answers

    What is the result of altering the DNA's primary sequence?

    <p>Mutation in the DNA</p> Signup and view all the answers

    What is the mechanism of action of DNA synthesis inhibitors?

    <p>Inhibition of DNA synthesis</p> Signup and view all the answers

    What is the effect of changing the DNA's configuration on DNA synthesis?

    <p>It inhibits DNA synthesis</p> Signup and view all the answers

    In Gram-negative bacteria, Topoisomerase II (DNA gyrase) is responsible for:

    <p>Relaxation of supercoiled DNA</p> Signup and view all the answers

    What is the result of inhibiting Topoisomerase II (DNA gyrase) in bacterial cells?

    <p>Supercoiling of DNA, preventing replication</p> Signup and view all the answers

    Which of the following is a target site for antibacterial agents?

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

    Topoisomerase II (DNA gyrase) is essential for:

    <p>Normal transcription and replication</p> Signup and view all the answers

    What is the consequence of Topoisomerase II (DNA gyrase) inhibition in Gram-negative bacteria?

    <p>Supercoiling of DNA, preventing replication</p> Signup and view all the answers

    What is the role of Topoisomerase IV in Gram positive bacteria?

    <p>Allows for decatenation of replicated DNA into daughter cells</p> Signup and view all the answers

    What happens when Topoisomerase IV is inhibited in Gram positive bacteria?

    <p>DNA replication is prevented</p> Signup and view all the answers

    What is the effect of Topoisomerase IV on DNA in Gram positive bacteria?

    <p>Separates replicated DNA into daughter cells</p> Signup and view all the answers

    What is the role of Topoisomerase IV in cell division?

    <p>Decatenates replicated DNA into daughter cells</p> Signup and view all the answers

    What is the result of Topoisomerase IV inhibition in Gram positive bacteria?

    <p>DNA decatenation is prevented</p> Signup and view all the answers

    What is the primary function of Topoisomerase IV in Gram positive bacteria?

    <p>Allows for decatenation of replicated DNA into daughter cells</p> Signup and view all the answers

    What is the consequence of inhibiting Topoisomerase IV in Gram positive bacteria?

    <p>Inhibition of DNA replication</p> Signup and view all the answers

    In which type of bacteria does Topoisomerase IV play a crucial role in cell division?

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

    What is the role of Topoisomerase IV in the process of DNA replication?

    <p>It decatenates the replicated DNA into daughter cells</p> Signup and view all the answers

    What would be the result of Topoisomerase IV inhibition in terms of bacterial growth?

    <p>Bacterial growth would be inhibited</p> Signup and view all the answers

    What is the purpose of the conformational change in the enzyme during the DNA gyrase process?

    <p>To lock the first DNA segment in place</p> Signup and view all the answers

    What is required for the 'locking' of the second DNA segment in place?

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

    What is the net result of one cycle of the DNA gyrase process?

    <p>The coiling of the DNA decreases by 1</p> Signup and view all the answers

    What happens to the first DNA segment after it is cut by the enzyme?

    <p>It is released and religated</p> Signup and view all the answers

    What is the role of the enzyme in the DNA gyrase process?

    <p>To cut and religate the first DNA segment</p> Signup and view all the answers

    What is the function of ATP in the DNA gyrase process?

    <p>To provide energy for the conformational change in the enzyme</p> Signup and view all the answers

    What happens to the first DNA segment after the enzyme cuts both strands?

    <p>It is religated and released</p> Signup and view all the answers

    What is the result of the second DNA segment passing through the enzyme?

    <p>The coiling of the DNA is changed by 1</p> Signup and view all the answers

    What is the role of the enzyme in the DNA gyrase process?

    <p>To form a conformational change to lock the DNA segment</p> Signup and view all the answers

    What is the order of the DNA gyrase process?

    <p>Engage DNA, conformational change, lock DNA segment</p> Signup and view all the answers

    Which mechanism of resistance in bacteria involves changes in the genes that encode enzymes?

    <p>Chromosomal mutations in the genes that encode one or both enzymes</p> Signup and view all the answers

    What is the result of the alteration in the expression of membrane porins in bacteria?

    <p>Increased antibiotic resistance</p> Signup and view all the answers

    What is the effect of altering efflux pumps in bacteria?

    <p>Increased antibiotic resistance</p> Signup and view all the answers

    What is the general effect of chromosomal mutations in the genes that encode one or both enzymes?

    <p>Increased antibiotic resistance</p> Signup and view all the answers

    What is the general effect of alteration in the expression of membrane porins?

    <p>Increased antibiotic resistance</p> Signup and view all the answers

    What is a mechanism of resistance to antibiotics that involves a genetic change?

    <p>Chromosomal mutations in the genes that encode one or both enzymes</p> Signup and view all the answers

    Which mechanism of resistance can confer cross-resistance to a class of antibiotics?

    <p>Generally confers cross-resistance in class</p> Signup and view all the answers

    What is the result of an alteration in the expression of membrane porins?

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

    What is a mechanism of antibiotic resistance that involves the active transport of antibiotics out of the bacterial cell?

    <p>Alteration in efflux pumps</p> Signup and view all the answers

    What is the consequence of chromosomal mutations in the genes that encode one or both enzymes involved in antibiotic resistance?

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

    What is the primary target of PABA analogues in bacterial cells?

    <p>Dihydropteroate synthetase</p> Signup and view all the answers

    How do Folate analogues prevent the conversion of dihydrofolate to tetrahydrofolate?

    <p>By competitively inhibiting dihydrofolate reductase</p> Signup and view all the answers

    What is the mechanism of action of PABA analogues?

    <p>Competitive inhibition of dihydropteroate synthetase</p> Signup and view all the answers

    What is the result of the inhibition of dihydropteroate synthetase by PABA analogues?

    <p>Prevention of folic acid formation</p> Signup and view all the answers

    What is the key difference between the mechanism of action of PABA analogues and Folate analogues?

    <p>PABA analogues inhibit dihydropteroate synthetase, while Folate analogues inhibit dihydrofolate reductase</p> Signup and view all the answers

    Which of the following mechanisms of resistance to sulfonamides involves the modification of an enzyme?

    <p>Altered dihydropteroate synthetase</p> Signup and view all the answers

    What is the result of enhanced production of PABA in bacteria?

    <p>Increased resistance to sulfonamides</p> Signup and view all the answers

    Which of the following mechanisms of resistance to sulfonamides involves the increased production of an enzyme?

    <p>Overproduction of dihydrofolate reductase</p> Signup and view all the answers

    What is the result of plasmid transfer or random mutations in bacteria?

    <p>Increased resistance to sulfonamides</p> Signup and view all the answers

    Which of the following mechanisms of resistance to sulfonamides involves the reduction of the permeability of the bacterial cell membrane?

    <p>Decreased permeability to sulfonamide</p> Signup and view all the answers

    What is a mechanism of resistance to sulfonamide antibiotics in bacteria?

    <p>Enhanced production of PABA</p> Signup and view all the answers

    How do bacteria develop resistance to folic acid antagonists?

    <p>By increasing the production of dihydrofolate reductase</p> Signup and view all the answers

    What is the effect of plasmid transfer or random mutations on bacterial resistance to antibiotics?

    <p>It leads to the development of antibiotic resistance</p> Signup and view all the answers

    What is the mechanism of resistance to sulfonamide antibiotics that involves altered enzyme activity?

    <p>Altered dihydropteroate synthetase</p> Signup and view all the answers

    Which of the following mechanisms of resistance to antibiotics is specific to sulfonamide antibiotics?

    <p>Altered dihydropteroate synthetase</p> Signup and view all the answers

    What is a mechanism of resistance to sulfonamide antibiotics?

    <p>Decreased permeability to sulfonamide</p> Signup and view all the answers

    How do bacteria develop resistance to folic acid antagonists?

    <p>Altered dihydropteroate synthetase or dihydrofolate reductase</p> Signup and view all the answers

    What is a mechanism of sulfonamide resistance in bacteria?

    <p>Overproduction of dihydrofolate reductase</p> Signup and view all the answers

    How do PABA analogues prevent folic acid formation in bacteria?

    <p>By inhibiting dihydropteroate synthetase</p> Signup and view all the answers

    What is a mechanism of resistance to sulfonamide antibiotics in bacteria?

    <p>Plasmid transfer or random mutations</p> Signup and view all the answers

    What is a mechanism of resistance to Folic Acid Antagonists in bacteria?

    <p>Overproduction of dihydrofolate reductase</p> Signup and view all the answers

    How do bacteria resist the effects of sulfonamides?

    <p>By decreasing permeability to sulfonamide</p> Signup and view all the answers

    What is the result of plasmid transfer or random mutations in bacteria?

    <p>Development of resistance to sulfonamides</p> Signup and view all the answers

    What is another mechanism of resistance to folic acid antagonists in bacteria?

    <p>Altered dihydropteroate synthetase or dihydrofolate reductase</p> Signup and view all the answers

    What is the role of PABA in folic acid synthesis?

    <p>It is a precursor to folic acid</p> Signup and view all the answers

    Study Notes

    Ribosomal RNA Function

    • 30S and 50S ribosomal subunits are key targets
    • 30S subunit is involved in decoding of mRNA
    • 50S subunit is involved in linking amino acids together
    • Both subunits are involved in translocating the translation machine

    Mechanism of Action

    • Bacterial protein synthesis is the target
    • Two sites involved: P site (peptidyl) and A site (aminoacyl)
    • Most agents target either 50S or 30S subunits and are selective to bacteria
    • Exceptions: Chloramphenicol has activity against protozoan parasites
    • Inhibiting organellar protein synthesis
    • Complete inhibition of protein synthesis is not necessary to kill bacteria
    • Most agents are bacteriostatic, except Aminoglycosides

    Mechanisms of Resistance

    • Unique to each class of agents
    • No specific details provided

    Fluoroquinolones

    • Quinolone structure with fluorine at position 6
    • Structural changes at positions 1, 5, 7, and 8
    • Inhibit DNA synthesis by changing DNA configuration, not primary sequence
    • Targets topoisomerase II (DNA gyrase) and topoisomerase IV
    • Topoisomerase II: relaxes supercoiled DNA in Gram-negative bacteria
    • Topoisomerase IV: involved in cell division in Gram-positive bacteria
    • Normal process: conformational change, ATP required, DNA segment "locked", and religated

    Mechanisms of Resistance to Fluoroquinolones

    • Chromosomal mutations in genes encoding topoisomerase II or IV
    • Alterations in membrane porins
    • Alterations in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Targets PABA analogues and folate analogues
    • PABA analogues (Sulfonamides) competitively inhibit Dihydropteroate synthetase
    • Folate analogues competitively inhibit dihydrofolate reductase
    • Prevents folic acid formation and conversion to active coenzyme form

    Mechanisms of Resistance to Folic Acid Antagonists

    • Plasmid transfer or random mutations
    • Altered dihydropteroate synthetase or dihydrofolate reductase
    • Decreased permeability to sulfonamide
    • Enhanced production of PABA
    • Overproduction of dihydrofolate reductase

    Ribosomal RNA Function

    • 30S and 50S ribosomal subunits are key targets
    • 30S subunit is involved in decoding of mRNA
    • 50S subunit is involved in linking amino acids together
    • Both subunits are involved in translocating the translation machine

    Mechanism of Action

    • Bacterial protein synthesis is the target
    • Two sites involved: P site (peptidyl) and A site (aminoacyl)
    • Most agents target either 50S or 30S subunits and are selective to bacteria
    • Exceptions: Chloramphenicol has activity against protozoan parasites
    • Inhibiting organellar protein synthesis
    • Complete inhibition of protein synthesis is not necessary to kill bacteria
    • Most agents are bacteriostatic, except Aminoglycosides

    Mechanisms of Resistance

    • Unique to each class of agents
    • No specific details provided

    Fluoroquinolones

    • Quinolone structure with fluorine at position 6
    • Structural changes at positions 1, 5, 7, and 8
    • Inhibit DNA synthesis by changing DNA configuration, not primary sequence
    • Targets topoisomerase II (DNA gyrase) and topoisomerase IV
    • Topoisomerase II: relaxes supercoiled DNA in Gram-negative bacteria
    • Topoisomerase IV: involved in cell division in Gram-positive bacteria
    • Normal process: conformational change, ATP required, DNA segment "locked", and religated

    Mechanisms of Resistance to Fluoroquinolones

    • Chromosomal mutations in genes encoding topoisomerase II or IV
    • Alterations in membrane porins
    • Alterations in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Targets PABA analogues and folate analogues
    • PABA analogues (Sulfonamides) competitively inhibit Dihydropteroate synthetase
    • Folate analogues competitively inhibit dihydrofolate reductase
    • Prevents folic acid formation and conversion to active coenzyme form

    Mechanisms of Resistance to Folic Acid Antagonists

    • Plasmid transfer or random mutations
    • Altered dihydropteroate synthetase or dihydrofolate reductase
    • Decreased permeability to sulfonamide
    • Enhanced production of PABA
    • Overproduction of dihydrofolate reductase

    Ribosomal RNA Function

    • 30S and 50S ribosomal subunits are key targets
    • 30S subunit is involved in decoding of mRNA
    • 50S subunit is involved in linking amino acids together
    • Both subunits are involved in translocating the translation machine

    Mechanism of Action

    • Bacterial protein synthesis is the target
    • Two sites involved: P site (peptidyl) and A site (aminoacyl)
    • Most agents target either 50S or 30S subunits and are selective to bacteria
    • Exceptions: Chloramphenicol has activity against protozoan parasites
    • Inhibiting organellar protein synthesis
    • Complete inhibition of protein synthesis is not necessary to kill bacteria
    • Most agents are bacteriostatic, except Aminoglycosides

    Mechanisms of Resistance

    • Unique to each class of agents
    • No specific details provided

    Fluoroquinolones

    • Quinolone structure with fluorine at position 6
    • Structural changes at positions 1, 5, 7, and 8
    • Inhibit DNA synthesis by changing DNA configuration, not primary sequence
    • Targets topoisomerase II (DNA gyrase) and topoisomerase IV
    • Topoisomerase II: relaxes supercoiled DNA in Gram-negative bacteria
    • Topoisomerase IV: involved in cell division in Gram-positive bacteria
    • Normal process: conformational change, ATP required, DNA segment "locked", and religated

    Mechanisms of Resistance to Fluoroquinolones

    • Chromosomal mutations in genes encoding topoisomerase II or IV
    • Alterations in membrane porins
    • Alterations in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Targets PABA analogues and folate analogues
    • PABA analogues (Sulfonamides) competitively inhibit Dihydropteroate synthetase
    • Folate analogues competitively inhibit dihydrofolate reductase
    • Prevents folic acid formation and conversion to active coenzyme form

    Mechanisms of Resistance to Folic Acid Antagonists

    • Plasmid transfer or random mutations
    • Altered dihydropteroate synthetase or dihydrofolate reductase
    • Decreased permeability to sulfonamide
    • Enhanced production of PABA
    • Overproduction of dihydrofolate reductase

    Ribosomal RNA Function

    • 30S and 50S ribosomal subunits are key targets
    • 30S subunit is involved in decoding of mRNA
    • 50S subunit is involved in linking amino acids together
    • Both subunits are involved in translocating the translation machine

    Mechanism of Action

    • Bacterial protein synthesis is the target
    • Two sites involved: P site (peptidyl) and A site (aminoacyl)
    • Most agents target either 50S or 30S subunits and are selective to bacteria
    • Exceptions: Chloramphenicol has activity against protozoan parasites
    • Inhibiting organellar protein synthesis
    • Complete inhibition of protein synthesis is not necessary to kill bacteria
    • Most agents are bacteriostatic, except Aminoglycosides

    Mechanisms of Resistance

    • Unique to each class of agents
    • No specific details provided

    Fluoroquinolones

    • Quinolone structure with fluorine at position 6
    • Structural changes at positions 1, 5, 7, and 8
    • Inhibit DNA synthesis by changing DNA configuration, not primary sequence
    • Targets topoisomerase II (DNA gyrase) and topoisomerase IV
    • Topoisomerase II: relaxes supercoiled DNA in Gram-negative bacteria
    • Topoisomerase IV: involved in cell division in Gram-positive bacteria
    • Normal process: conformational change, ATP required, DNA segment "locked", and religated

    Mechanisms of Resistance to Fluoroquinolones

    • Chromosomal mutations in genes encoding topoisomerase II or IV
    • Alterations in membrane porins
    • Alterations in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Targets PABA analogues and folate analogues
    • PABA analogues (Sulfonamides) competitively inhibit Dihydropteroate synthetase
    • Folate analogues competitively inhibit dihydrofolate reductase
    • Prevents folic acid formation and conversion to active coenzyme form

    Mechanisms of Resistance to Folic Acid Antagonists

    • Plasmid transfer or random mutations
    • Altered dihydropteroate synthetase or dihydrofolate reductase
    • Decreased permeability to sulfonamide
    • Enhanced production of PABA
    • Overproduction of dihydrofolate reductase

    Mechanism of Action

    • Bacterial protein synthesis involves Ribosomal RNA (rRNA) that differs from other organisms.
    • The 30S subunit is responsible for decoding mRNA.
    • The 50S subunit links together amino acids to form a peptide chain.
    • Both subunits (30S and 50S) are involved in translocating the translation machine.
    • The ribosome has two sites: P “peptidyl” site and A “aminoacyl” site.
    • The P “peptidyl” site contains the growing peptide chain.
    • The A “aminoacyl” site binds incoming tRNA containing amino acids.

    Mechanism of Action

    • Bacterial protein synthesis involves Ribosomal RNA (rRNA) that differs from other organisms.
    • The 30S subunit is responsible for decoding mRNA.
    • The 50S subunit links together amino acids to form a peptide chain.
    • Both subunits (30S and 50S) are involved in translocating the translation machine.
    • The ribosome has two sites: P “peptidyl” site and A “aminoacyl” site.
    • The P “peptidyl” site contains the growing peptide chain.
    • The A “aminoacyl” site binds incoming tRNA containing amino acids.

    Sites of Action

    • Antibiotics target either 50S or 30S ribosomal subunits
    • Most antibiotics are selective to bacteria, but not chloramphenicol
    • Some antibiotics also show activity against protozoan and parasites

    Mechanism of Action

    • Antibiotics inhibit organellar protein synthesis
    • Complete inhibition of protein synthesis does not kill bacteria
    • Most antibiotics are bacteriostatic, except for aminoglycosides

    Quinolone Structure and Mechanism of Action

    • Quinolone structure features a fluorine atom at position 6
    • Structural modifications occur at positions 1, 5, 7, and 8

    Quinolone Structure and Mechanism of Action

    • Quinolone structure features a fluorine atom at position 6
    • Structural modifications occur at positions 1, 5, 7, and 8

    Bacterial Protein Synthesis

    • Provides the machinery for:
      • Decoding of mRNA (30S)
      • Linking together of the amino acids (50S)
      • Translocating of the translation machine (both subunits)
    • Two sites:
      • P "peptidyl" site – contains the growing peptide chain
      • A "aminoacyl" site – binds incoming tRNA containing amino acids
    • Sites of action:
      • Most target either 50S or 30S
      • Most are selective to bacteria
      • Exception: Chloramphenicol, also has activity against protozoan, parasites
    • Inhibits organellar protein synthesis
    • Complete inhibition of protein synthesis will not kill bacteria
    • Most agents are bacteriostatic, except for Aminoglycosides

    Fluoroquinolones

    • Structure and Mechanism of action:
      • Bactericidal, Concentration-Dependent Killing, Post-antibiotic Effect
      • Key structural components:
        • Quinolone structure - Fluorine at position 6
        • Structural changes at 1, 5, 7, and 8 positions
    • Mechanism of action:
      • Inhibition of DNA synthesis
      • Change the configuration of the DNA
      • Do not change the DNA’s primary sequence
    • Sites of action:
      • Topoisomerase II (DNA gyrase)
        • Gram negatives, allows relaxation of supercoiled DNA
        • Inhibition results in supercoiling, preventing DNA replication
      • Topoisomerase IV – Role in cell division
        • Gram positives, allows for decatenation of replicated DNA
        • Inhibition prevents DNA replication
    • Mechanisms of Resistance:
      • Chromosomal mutations in the genes that encode one or both enzymes
      • Alteration in the expression of membrane porins
      • Alteration in efflux pumps
      • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Mechanism of action:
      • Bacteriostatic, Time-Dependent Killing, Bactericidal when combined
      • Drug action targets:
        • Paraaminobenzoic Acid (PABA) analogues
        • Folate analogues
    • Mechanism of action:
      • PABA analogues (Sulfonamides):
        • Competitively inhibit Dihydropteroate synthetase
        • Unique to bacteria
        • Prevents folic acid formation
      • Folate analogues:
        • Competitively inhibit dihydrofolate reductase
        • Higher affinity to bacterial reductase
        • Prevents conversion to active coenzyme form (Tetrahydrofolic acid)
    • Mechanisms of Resistance:
      • Plasmid transfer or random mutations
      • Altered dihydropteroate synthetase or dihydrofolate reductase
      • Decreased permeability to sulfonamide
      • Enhanced production of PABA
      • Overproduction of dihydrofolate reductase

    Sites of Action

    • Topoisomerase II (DNA gyrase) is a site of action, specifically in Gram-negative bacteria
    • It plays a crucial role in allowing the relaxation of supercoiled DNA, which is necessary for normal transcription and replication
    • Inhibition of Topoisomerase II (DNA gyrase) results in supercoiling, which prevents DNA replication

    Protein Synthesis Inhibitors

    • Targets: 30S and 50S ribosomal subunits
    • Mechanism of action:
      • Provides machinery for decoding of mRNA (30S) and linking of amino acids (50S)
      • Two sites: P "peptidyl" site (growing peptide chain) and A "aminoacyl" site (binds incoming tRNA containing amino acids)
    • Sites of action:
      • Most target either 50S or 30S
      • Most are selective to bacteria
      • Exception: Chloramphenicol (also active against protozoan, parasites)
    • Inhibit organellar protein synthesis
    • Complete inhibition of protein synthesis will not kill bacteria
      • Most agents are bacteriostatic (Exception: Aminoglycosides)

    Fluoroquinolones

    • Structure:
      • Quinolone structure with fluorine at position 6
      • Structural changes at 1, 5, 7, and 8 positions
    • Mechanism of action:
      • Inhibition of DNA synthesis
      • Change the configuration of the DNA
      • Do not change the DNA's primary sequence
    • Sites of action:
      • Topoisomerase II (DNA gyrase)
        • Gram negatives: allows relaxation of supercoiled DNA necessary for normal transcription and replication
        • Inhibition results in supercoiling which prevents DNA replication
      • Topoisomerase IV - Role in cell division
        • Gram positives: allows for decatenation of replicated DNA into daughter cells
        • Inhibition prevents DNA replication
    • Mechanisms of resistance:
      • Chromosomal mutations in genes that encode one or both enzymes
      • Alteration in expression of membrane porins
      • Alteration in efflux pumps
      • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Mechanism of action:
      • PABA analogues (Sulfonamides)
        • Competitively inhibit Dihydropteroate synthetase
        • Unique to bacteria
        • Prevents folic acid formation
      • Folate analogues
        • Competitively inhibit dihydrofolate reductase
        • Higher affinity to bacterial reductase
        • Prevents conversion to active coenzyme form (Tetrahydrofolic acid)
    • Mechanisms of resistance:
      • Plasmid transfer or random mutations
      • Altered dihydropteroate synthetase or dihydrofolate reductase
      • Decreased permeability to sulfonamide
      • Enhanced production of PABA
      • Overproduction of dihydrofolate reductase

    Mechanism of Action

    • Bacterial protein synthesis:
      • Provides machinery for decoding of mRNA (30S) and linking together of amino acids (50S)
      • Translocating of the translation machine (both subunits)
    • Two sites:
      • P "peptidyl" site – contains the growing peptide chain
      • A "aminoacyl" site – binds incoming tRNA containing amino acids

    Key Targets in Ribosomal RNA Function

    • 30S ribosomal subunit
    • 50S ribosomal subunit

    Sites of Action

    • Most target either 50S or 30S
    • Most are selective to bacteria
    • Exception: Chloramphenicol
    • Also some activity against protozoan, parasites
    • Inhibit organellar protein synthesis
    • Complete inhibition of protein synthesis will not kill bacteria
    • Most agents are bacteriostatic (Exception: Aminoglycosides)

    Fluoroquinolones

    • Quinolone structure - Fluorine at position 6
    • Structural changes at 1, 5, 7, and 8 positions
    • Mechanism of action:
      • Inhibition of DNA synthesis
      • Change the configuration of the DNA
      • Do not change the DNA’s primary sequence
    • Sites of action:
      • Topoisomerase II (DNA gyrase) - Gram negatives
        • Allows relaxation of supercoiled DNA necessary for normal transcription and replication
        • Inhibition results in supercoiling which prevents DNA replication
      • Topoisomerase IV - Gram positives
        • Allows for decatenation of replicated DNA into daughter cells
        • Inhibition prevents DNA replication
    • Normal process for DNA gyrase:
      • Type II topoisomerase enzymes engage DNA
      • Conformational change in enzyme to “lock” DNA segment
      • Second segment of DNA is “locked” into place (ATP required)
      • Enzyme cuts both strands of the first DNA segment (nicking)
      • Second DNA segment passes through the enzyme
      • Changes the coiling of the DNA by 1
      • Second segment is released and first segment is religated and released

    Mechanisms of Resistance

    • Chromosomal mutations in the genes that encode one or both enzymes
    • Alteration in the expression of membrane porins
    • Alteration in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Mechanism of action:
      • PABA analogues (Sulfonamides) - competitively inhibit dihydropteroate synthetase
      • Folate analogues - competitively inhibit dihydrofolate reductase
    • Sites of action:
      • PABA analogues (Sulfonamides) - unique to bacteria
      • Folate analogues - higher affinity to bacterial reductase
    • Mechanisms of Resistance:
      • Plasmid transfer or random mutations
      • Altered dihydropteroate synthetase or dihydrofolate reductase
      • Decreased permeability to sulfonamide
      • Enhanced production of PABA
      • Overproduction of dihydrofolate reductase

    Mechanism of Action

    • Bacterial protein synthesis:
      • Provides machinery for decoding of mRNA (30S) and linking together of amino acids (50S)
      • Translocating of the translation machine (both subunits)
    • Two sites:
      • P "peptidyl" site – contains the growing peptide chain
      • A "aminoacyl" site – binds incoming tRNA containing amino acids

    Key Targets in Ribosomal RNA Function

    • 30S ribosomal subunit
    • 50S ribosomal subunit

    Sites of Action

    • Most target either 50S or 30S
    • Most are selective to bacteria
    • Exception: Chloramphenicol
    • Also some activity against protozoan, parasites
    • Inhibit organellar protein synthesis
    • Complete inhibition of protein synthesis will not kill bacteria
    • Most agents are bacteriostatic (Exception: Aminoglycosides)

    Fluoroquinolones

    • Quinolone structure - Fluorine at position 6
    • Structural changes at 1, 5, 7, and 8 positions
    • Mechanism of action:
      • Inhibition of DNA synthesis
      • Change the configuration of the DNA
      • Do not change the DNA’s primary sequence
    • Sites of action:
      • Topoisomerase II (DNA gyrase) - Gram negatives
        • Allows relaxation of supercoiled DNA necessary for normal transcription and replication
        • Inhibition results in supercoiling which prevents DNA replication
      • Topoisomerase IV - Gram positives
        • Allows for decatenation of replicated DNA into daughter cells
        • Inhibition prevents DNA replication
    • Normal process for DNA gyrase:
      • Type II topoisomerase enzymes engage DNA
      • Conformational change in enzyme to “lock” DNA segment
      • Second segment of DNA is “locked” into place (ATP required)
      • Enzyme cuts both strands of the first DNA segment (nicking)
      • Second DNA segment passes through the enzyme
      • Changes the coiling of the DNA by 1
      • Second segment is released and first segment is religated and released

    Mechanisms of Resistance

    • Chromosomal mutations in the genes that encode one or both enzymes
    • Alteration in the expression of membrane porins
    • Alteration in efflux pumps
    • Generally confers cross-resistance in class

    Folic Acid Antagonists

    • Mechanism of action:
      • PABA analogues (Sulfonamides) - competitively inhibit dihydropteroate synthetase
      • Folate analogues - competitively inhibit dihydrofolate reductase
    • Sites of action:
      • PABA analogues (Sulfonamides) - unique to bacteria
      • Folate analogues - higher affinity to bacterial reductase
    • Mechanisms of Resistance:
      • Plasmid transfer or random mutations
      • Altered dihydropteroate synthetase or dihydrofolate reductase
      • Decreased permeability to sulfonamide
      • Enhanced production of PABA
      • Overproduction of dihydrofolate reductase

    Normal Process of DNA Gyrase

    • Type II topoisomerase enzymes engage with DNA
    • A conformational change occurs in the enzyme, enabling it to "lock" a DNA segment in place
    • A second segment of DNA is "locked" into place, requiring ATP
    • The enzyme cuts both strands of the first DNA segment through a process called nicking
    • The second DNA segment passes through the enzyme, changing the coiling of the DNA by 1
    • The second segment is released, and the first segment is religated and released

    Normal Process of DNA Gyrase

    • Type II topoisomerase enzymes engage with DNA
    • A conformational change occurs in the enzyme, enabling it to "lock" a DNA segment in place
    • A second segment of DNA is "locked" into place, requiring ATP
    • The enzyme cuts both strands of the first DNA segment through a process called nicking
    • The second DNA segment passes through the enzyme, changing the coiling of the DNA by 1
    • The second segment is released, and the first segment is religated and released

    Mechanisms of Resistance

    • Chromosomal mutations occur in genes that encode one or both enzymes, leading to resistance.
    • Alterations in the expression of membrane porins contribute to resistance.
    • Alterations in efflux pumps also play a role in resistance.
    • This type of resistance generally confers cross-resistance within a class.

    Mechanisms of Resistance

    • Chromosomal mutations occur in genes that encode one or both enzymes, leading to resistance.
    • Alterations in the expression of membrane porins contribute to resistance.
    • Alterations in efflux pumps also play a role in resistance.
    • This type of resistance generally confers cross-resistance within a class.

    Mechanism of Action

    • Sulfonamides are bacteriostatic, but can be bactericidal when combined with other drugs
    • They work by targeting two main drug action targets: Paraaminobenzoic Acid (PABA) analogues and Folate analogues

    PABA Analogues (Sulfonamides)

    • Competitively inhibit Dihydropteroate synthetase, a unique enzyme found only in bacteria
    • Inhibition prevents folic acid formation, which is essential for bacterial growth and survival

    Folate Analogues

    • Competitively inhibit dihydrofolate reductase, an enzyme that plays a crucial role in folic acid synthesis
    • Folate analogues have a higher affinity for bacterial dihydrofolate reductase compared to human enzymes
    • Inhibition prevents the conversion of dihydrofolic acid to tetrahydrofolic acid, the active coenzyme form necessary for bacterial growth

    Mechanisms of Resistance

    • Bacteria acquire resistance to sulfonamides through plasmid transfer or random mutations.
    • Altered dihydropteroate synthetase or dihydrofolate reductase enzymes reduce the effectiveness of sulfonamides.
    • Decreased permeability to sulfonamides prevents the antibiotic from reaching its target site.
    • Enhanced production of PABA (para-aminobenzoic acid) competes with sulfonamides, reducing their antibacterial activity.
    • Overproduction of dihydrofolate reductase, an enzyme essential for bacterial metabolism, allows bacteria to counteract the effects of sulfonamides.

    Mechanisms of Resistance

    • Bacteria acquire resistance to sulfonamides through plasmid transfer or random mutations.
    • Altered dihydropteroate synthetase or dihydrofolate reductase enzymes reduce the effectiveness of sulfonamides.
    • Decreased permeability to sulfonamides prevents the antibiotic from reaching its target site.
    • Enhanced production of PABA (para-aminobenzoic acid) competes with sulfonamides, reducing their antibacterial activity.
    • Overproduction of dihydrofolate reductase, an enzyme essential for bacterial metabolism, allows bacteria to counteract the effects of sulfonamides.

    Mechanisms of Resistance

    • Bacteria acquire resistance to sulfonamides through plasmid transfer or random mutations.
    • Altered dihydropteroate synthetase or dihydrofolate reductase enzymes reduce the effectiveness of sulfonamides.
    • Decreased permeability to sulfonamides prevents the antibiotic from reaching its target site.
    • Enhanced production of PABA (para-aminobenzoic acid) competes with sulfonamides, reducing their antibacterial activity.
    • Overproduction of dihydrofolate reductase, an enzyme essential for bacterial metabolism, allows bacteria to counteract the effects of sulfonamides.

    Mechanisms of Resistance

    • Bacteria acquire resistance to sulfonamides through plasmid transfer or random mutations.
    • Altered dihydropteroate synthetase or dihydrofolate reductase enzymes reduce the effectiveness of sulfonamides.
    • Decreased permeability to sulfonamides prevents the antibiotic from reaching its target site.
    • Enhanced production of PABA (para-aminobenzoic acid) competes with sulfonamides, reducing their antibacterial activity.
    • Overproduction of dihydrofolate reductase, an enzyme essential for bacterial metabolism, allows bacteria to counteract the effects of sulfonamides.

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    This quiz covers the key targets in ribosomal RNA function, including the 30S and 50S ribosomal subunits, and their role in bacterial protein synthesis. It also explains the mechanism of action of ribosomal RNA in decoding mRNA, linking amino acids, and translocating the translation machine.

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