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Antibiotics and Protein Synthesis
Antibiotics are molecules produced by microorganisms as defense mechanisms. The most effective antibiotics work by interfering with essential biochemical or reproductive processes. Many antibiotics block or disrupt one or more stages in protein synthesis. Some of these are mentioned here.
Tetracyclines are a family of chemically related compounds used to treat several types of bacterial infections. Tetracyclines interfere with the initiation of translation. The tetracycline molecule attaches to the small ribosomal subunit and prevents binding of the tRNA anticodon during initiation. Both eukaryotic and prokaryotic ribosomes are sensitive to the action of tetracycline, but this antibiotic cannot pass through the plasma membrane of eukaryotic cells. Because tetracycline can enter bacterial cells to inhibit protein synthesis, it will stop bacterial growth, helping the immune system fight the infection.
Streptomycin is used in hospitals to treat serious bacterial infections. It binds to the small ribosomal subunit but does not prevent initiation or elongation; however, it does affect the efficiency of protein synthesis. Binding of streptomycin changes the way mRNA codons interact with the tRNA. As a result, incorrect amino acids are incorporated into the growing polypeptide chain, producing nonfunctional proteins. In addition, streptomycin causes the ribosome to randomly fall off the mRNA, preventing the synthesis of complete proteins.
Puromycin is not used clinically but has played an important role in studying the mechanism of protein synthesis in the research laboratory. The puromycin molecule is the same size and shape as a tRNA/amino acid complex. When puromycin enters the ribosome, it can be incorporated into a growing polypeptide chain, stopping further synthesis because no peptide bond can be formed between puromycin and an amino acid, causing the shortened polypeptide to fall off the ribosome.
Chloramphenicol was one of the first broadspectrum antibiotics introduced. Eukaryotic cells are resistant to its actions, and it was widely used to treat bacterial infections. However, its use is limited to external applications and serious infections. Chloramphenicol destroys cells in the bone marrow, the source of all blood cells. In bacteria, this antibiotic binds to the large ribosomal subunit and inhibits the formation of peptide bonds. Another antibiotic, erythromycin, also binds to the large ribosomal subunit and inhibits the movement of ribosomes along the mRNA.
Almost every step of protein synthesis can be inhibited by one antibiotic or another. Work on designing new synthetic antibiotics to fight infections is based on our knowledge of how the
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Why is targeting protein synthesis an effective strategy for preventing infection?
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Chapter 9 Solutions
Human Heredity: Principles and Issues (MindTap Course List)
- Which of the following types of mutation that changes the mRNA sequence after the codon that initiates translation is likely to have the most detrimental effect on the polypeptide product? Group of answer choices a substitution of the first nucleotide of a GGG codon a substitution of the third nucleotide in an ACC codon an insertion of a codon a deletion of two nucleotides a deletion of a codonarrow_forwardMatch the following with the correct nucleic acid. (mRNA, tRNA, rRNA, or All RNA) 1. This molecule is complementary to DNA. 2. This molecule is part of translation. 3. This molecule is part of the ribosome. 4. This molecule contains anticodons. 5. This molecule is esponsible for bringing amino acids to the ribosome. 6. DNA is used as a template to create this type of RNA molecule. 7. This molecule is part of transcription. 8. This molecule contains codons.arrow_forwardWhich of the following is true about transfer RNA during translation? -Transfer RNA has anticodons that match with mRNA codons -Transfer RNA carries small ribosome subunits - Transfer RNA carries fully-functioning proteins at the end of translation -Transfer RNA carries ATP for energy during translationarrow_forward
- Which of the following statements about the translation process is correct? a. RNA is made complimentary to DNA b. A protein is made from the DNA base sequence c. DNA is made complimentary to RNA d. A protein is made from the RNA base sequencearrow_forwardWhich of the following mutations would be most likely to have the most negative effect on the functioning of a protein produced by the gene? Group of answer choices a deletion of one nucleotide at the beginning of the coding sequence a substitution of one nucleotide at the beginning of the coding sequence an insertion of three nucleotides near the end of the coding sequence a substitution of one nucleotide near the end of the coding sequencearrow_forwardIndicate which of the following items are associated with transcription or translation. This could be in prokaryotes or eukaryotes, or both. Group of answer choices: Translation OR Transcription Sigma binds to the promoter mRNA binds to the small ribosomal subunit Spliceosomes remove introns and splice together exons Nucleotides are added from the 5' to 3' end tRNA anticodon binds to the corresponding mRNA codon STOP codon results in terminationarrow_forward
- Some antibiotic drugs fight infection by interfering with DNA replication, transcription, or translation in bacteria. Indicate whether each of the following antibiotic drug effects is on replication, transcription, or translation. HINT Each answer (replication, transcription, and translation) is used only once for the following: a. Rifampin binds to bacterial RNA polymerase. b. Streptomycin binds bacterial ribosomes, disabling them. c. Quinolone blocks an enzyme that prevents bacterial DNA from unwinding.arrow_forwardWhich of the following would shift the reading frame in mRNA? substitution of a purine-pyrimidine pair by a pyrimidine-purine base? Introduction of a silent mutation insertion of a new base pair in the DNA deamination of cytosine to uracilarrow_forwardAn antibiotic is a drug that kills or inhibits the growth of microorganisms. The use of antibiotics has been of great importance in the battle against many infectious diseases caused by microorganisms. The mode of action for many antibiotics is to inhibit the translation process within bacterial cells. Certain antibiotics selectively bind to bacterial (70S) ribosomes but do not inhibit eukaryotic (80S) ribosomes. Why would an antibiotic bind to a bacterial ribosome but not to a eukaryotic ribosome? Why does this binding inhibit growth?arrow_forward
- Each of the following statements about protein synthesis is false.Correct each to make a true statement. a. In a gene, each nucleotide specifies one amino acid in a protein sequence. b. A transcription factor must bind to the promoter region of a gene before the enzyme DNA synthetase is able to bind and begin transcription. c. The enzyme RNA polymerase builds a strand of transfer RNA, whose codons are complementary to DNA’s triplets. d. Proteins destined for secretion from the cell enter the nucleus after translation, to be folded and modified. e. During translation, amino acids are delivered by the messenger RNA transcriparrow_forwardWhich of the following statements regarding the genetic code is false? The genetic code is nearly universal. Each codon codes for only one amino acid. Three different codons function to terminate translation. There is a single initiation codon. Each amino acid is encoded by a single codon.arrow_forwardWhich of the following statements about translation is false? In eukaryotes, the 5' cap and the 3' poly(A) tail are involved in translation initiation. Peptidyl-transferase activity during translation is the property of a ribozyme. A base at the first position of an anticodon on the tRNA would pair with a base at the third position of the mRNA. The growing peptide chain is transferred from the tRNA in the P site to the tRNA in the A site. Ribosomes move along an mRNA in the 3’ → 5' direction.arrow_forward
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning