Concept explainers
Antibiotics are chemically diverse antimicrobial compounds produced by microorganisms. Each antibiotic works by inhibiting a specific cellular process in the target microorganisms. The β-lactam antibiotics, including penicillins and cephalosporins, target bacterial cell wall synthesis and are the most important class of clinical antibiotics. The aminoglycosides, macrolides, and tetracycline antibiotics selectively interfere with protein synthesis in Bacteria. The quinolones are an important class of synthetic antibacterial drugs that inhibit DNA synthesis. Daptomycin and platensimycin are structurally novel antibiotics that target cytoplasmic membrane functions and lipid biosynthesis, respectively.
What are the common sources for natural antibiotics? How do these antimicrobial drugs differ from growth factor analogs, such as the sulfa drugs? Why are β-lactam antibiotics generally more effective against gram-positive bacteria than against gram-negative bacteria?
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Brock Biology of Microorganisms, Books a la Carte Edition
- Your lab was asked to recommend the best treatment for the patient with a urinary tract infection. Based on the sequencing results, the resistance that was observed against the β-lactam antibiotic amoxicillin likely results from the production of a β-lactamase, an enzyme that degrades β-lactams. However, it is still possible to use β-lactam antibiotics to treat infections caused by bacteria that produce β-lactamases. Some β-lactam antibiotics cannot be degraded very easily by β-lactamases. In addition, β-lactam antibiotics are often co-prescribed with β-lactamase inhibitors, drugs that interfere with β-lactamases and protect β-lactams. Therefore, to identify the best treatment for this bacterial infection, further characterization of the β-lactamase enzyme is needed. A recombinant form of the β-lactamase can be produced in a lab strain of Escherichia coli. This enzyme can then be purified, and its activity and inhibition tested using in vitro enzyme assays. To generate the…arrow_forwardIdentify and briefly describe (one sentence) the structural element(s) that allow for the 3 ways by which nutrients go in and out of the cell. a._______________________________________________________________ b._______________________________________________________________ c._______________________________________________________________ 2. Microorganisms can thrive under many different conditions, including high-temperature environments such as hot springs. To function properly, cell membranes have to be in a fluid state. How do you expect the fatty acid content (saturated versus unsaturated) of bacteria living in high-temperature environments might compare with that of bacteria living in more moderate temperatures?arrow_forwardProtein synthesis occurs in all living cells. Why, then, are some antimicrobial drugs that target protein synthesis selectively toxic to bacteria? The protein synthesis in human cells will only occur inside the nucleus. The ribosomes found in human cells and those found in bacterial cells have different structures. Protein synthesis in bacteria is completed by ribosomes, while protein synthesis in humans is completed by polymerase enzymes. The protein synthesis in human cells occurs less frequently than that in bacterial cells.arrow_forward
- The informational biopolymers DNA, RNA and protein all share some features, but differ in others. Which of the following are common features, shared by all three? -the order of monomer addition during synthesis is directed by a template biopolymer. -during synthesis monomers are incorporated in groups of 3. -all contain a phosphate group in the polymer backbone. -during synthesis individual polymer chains are extended at only one of the two ends. -monomer selection during chain growth is an indirect process involving an adaptor molecule. More than one answer is correct Please help I’m confusedarrow_forwardWhich one of the following is NOT a biochemical property associated with exotoxins Group of answer choices binding to cholesterol N glycosidase activity peptidase activity ADP ribosyl transferase activity cAMP activityarrow_forwardName an example of each of the following classes ofcompounds:a. glycoproteinb. proteoglycanc. disaccharided. glycosaminoglycan (GAG)arrow_forward
- A researcher creates random copolymers of three nucleotides each by mixing polynucleotide phosphorylase with guanine and adenine nucleotides in a ratio of 5 guanine nucleotides to 1 adenine. Give the different copolymers produced and their theoretical proportions.arrow_forwardEukaryotic protein synthesis is considerably slower than synthesis of prokaryotes. Explainarrow_forward49. Which of the following are CORRECTLY linked to their requirement for bacterial growth ? Group of answer choices PABA ( para amino benzoic acid) ::::: precursor for folic acid synthesis nitrogen ::::: for amine group ( -NH2)of amino acids & nitrogenous bases heme ::::: critical for cytochromes (in electron transport chain) purines & pyrimidines :::: nucleic acid synthesis phosphorous :::: DNA, RNA, phospholipids all of the above 50. What would you assume about an obligate aerobe ? Group of answer choices they have lipid A in their cell wall it's comparable to a microaerophiles more growth would be observed compared to an anaerobe under similar conditions lower SOD and catalase levels don't match with how it behaves in the presence of oxygen undergoes slow metabolism ( in presence of oxygen) ; more dormant cells than anaerobes can’t tolerate atmospheric oxygenarrow_forward
- All three types of biopolymers are set from the building blocks with similar types of chemical reactions. Draw the chemical reaction formula for the polymerization reaction. Describe two non-covalent interactions that stabilize a tertiary structure of a protein. c.When describing the structure of proteins, it is often done at different levels. Explain what is meant by the following structural levels: primary structure secondary structure tertiary structure quaternary structurearrow_forwardWhich of the following organisms incorporates peptides along with carbohydrates in its cell wall structures? plants animals bacteria fungiarrow_forwardAntibiotics 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 nucleotide sequence of mRNA is converted into the amino acid sequence of a protein. Questions Why is targeting protein synthesis an effective strategy for preventing infection?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning