week five mastering
Streptomycin is a broad-spectrum antibiotic that binds to ribosomes. Which bacterial process does streptomycin inhibit?
Protein synthesis
Sally decides to go through the desensitization program recommended by her doctor. What is the overall purpose/goal of this process?
Repeated exposure to wasp venom antigen will increase the amount of IgG produced by Sally's immune system.
The IgG molecules that are produced during desensitization function as blocking antibodies. These antibodies are extremely effective in providing protection from a hypersensitivity reaction. Why are blocking IgG antibodies so effective at protecting Sally from another anaphylactic response to wasp venom?
The blocking IgG antibodies "outnumber" the IgE antibodies and bind to wasp venom before the IgE antibodies can bind.
What is the hygiene hypothesis?
The idea that childhood exposure to microorganisms helps prevent development of microbial diseases and autoimmune disorders.
Scott's pimples result from the inflammatory response generated in his hair follicles. The statements below describe events that occur during this response. Place the following statements in the chronological order that best describes the sequence of events leading to the appearance of acne.
The sequence of events from beginning to end are: 1.Overproduction of sebum leads to an accumulation in the follicle. 2.P. acnes metabolized glycerol in sebum, forming free fatty acids. 3.Free fatty acids stimulate the release of pro-inflammatory cytokines within the follicle. 4.The blood vessels surrounding the follicle dilate and become more permeable. 5. Immune cells such as neutrophils and phagocytes move into the follicle to try to eliminate P. acnes. 6. The buildup of dead cells, bacteria, and body fluids causes a raised pustule on the skin surface
There are a large number of antibiotics that inhibit protein synthesis at 70S ribosomes found in bacterial cells but do not interfere with protein synthesis at the 80S ribosomes found in eukaryotic cells. Some of these antibiotics bind to the smaller ribosomal subunit and interfere with the reading of the mRNA code, whereas others bind to the larger ribosomal subunit and inhibit the formation of peptide bonds. Unfortunately, some of the antibiotics that inhibit protein synthesis in bacteria exhibit some toxicity to the eukaryotic host cells as well. What is the most likely reason for this toxicity to the host cell?
These antibiotics interfere with protein synthesis within eukaryotic mitochondria.
Why do antibiotics not work against viruses?
Viruses do not contain antibiotic targets.
When the wasps stung Sally, the injection of venom initiated a type I hypersensitivity reaction called anaphylaxis. Which of the following best describes a hypersensitivity reaction?
a reaction that occurs in a sensitized individual resulting in tissue damage rather than immunity
The importance of gastrointestinal microbiota is a focus of this Big Picture Activity and stems from the need to better understand the causes of several gastrointestinal diseases. Which of the following terms describes the cause of inflammatory bowel diseases (IBD)?
autoimmune disease
One of the proposed treatments for IBD mentioned in the activity is transplant of microbes from one individual to another using what is referred to as "fecal microbiota transplantation" (FMT), which includes treatment with oral "poop pills" and also injection of donated stool samples into the rectum. The idea behind this treatment is to replenish microbiota that has been lost from the digestive tract. This treatment has shown to be successful in helping patients with C. difficile infections. Which of the following represents another means of replenishing the microbiota of the gastrointestinal tract?
eating yogurt containing live Lactobacillus cultures
Misuse of antibiotics leads to drug resistant bacterial populations by __________.
killing off all susceptible bacteria, selecting for those bacteria that are naturally resistant
Which of the following is true regarding systemic anaphylactic reactions?
- Systemic reactions can result in a dramatic decrease in blood pressure. - Systemic reactions are commonly associated with injected antigens. - A systemic reaction can be fatal in only a few minutes.
Predict which of the following outcomes would result from taking an antihistamine.
- decreased histamine -based stimulation of cells - decreased permeability of blood vessels - decreased mucus secretions
Identify the statements below that accurately describe the mechanisms through which organisms acquire antibiotic resistance. Select all of the statements that accurately describe the origins and spread of antibiotic resistance.
-Antibiotic-resistance genes can be passed horizontally via bacterial conjugation. -Antibiotic-resistance genes can be passed horizontally via transduction. -Antibiotic resistance is readily transmitted to the next generation during binary fission. -Mutations are the ultimate source of antibiotic-resistance genes. -Antibiotic-resistance genes can be passed from one bacterium to another by bacterial transformation. -Antibiotics select for those microbes that have developed resistance, increasing their frequency in the bacterial population.
Dr. Smith assures Scott that although inflammation may sound scary, there are several possible options for treating Scott's moderate acne. Which of the following would be the most appropriate for Scott's case? Select all that apply.
-Clear Light, a nonchemical, light-based system -topical treatment with a product containing benzoyl peroxide -an oral antibiotic such as erythromycin
Which of the following mediators are involved in anaphylactic reactions?
-Mast cells -IgE -Basophils
Part of the reason for Scott's acne is the overproduction of sebum. Scott's initial instinct is that shutting down production of sebum would be the quickest route to eliminating his acne; however, sebum actually plays an important role in maintaining the skin as a first line of defense against pathogens. Which of the following best describes the role of sebum as a component of the first line of defense?
-Sebum helps to keep the pH of the skin low, which inhibits the growth of microorganisms -Sebum forms a protective layer over the skin.
Consider the different mechanisms through which antibiotics inhibit microbial growth, and consider what changes in the microbe might enable it to resist the inhibitory effects of antibiotics. Select all of the statements that describe a mechanism that would enable a microorganism to resist the action of an antibiotic.
-Target site is modified, so that an antibiotic is unable to bind to its target. -A microbe develops a transport mechanism in the plasma membrane that rapidly pumps antibiotic out of the bacterial cell. -Altered porins in the cell wall block passage of antibiotic through the cell wall. -An enzyme that destroys the antibiotic is produced.
Acne is the result of the inflammatory response. In this case, the inflammation is resulting in acne that is very painful (physically and emotionally) for Scott. However, inflammation is a critical component of a normal immune response. What are the main functions of the inflammatory response? Select all that apply.
-destroying and eliminating the invading pathogen -"walling off" the site of injury or infection -repairing tissue damage resulting from inflammation
Dr. Smith prescribes oral erythromycin for Scott. She also recommends that he consider using an over-the-counter gel or cream containing benzoyl peroxide. Although this regimen should be effective at treating Scott's acne, there are some possible side effects. Which of the following are possible side effects of Scott's treatment? Select all that apply.
-excessive drying of the skin -gastrointestinal problems resulting from a reduction/elimination of normal intestinal flora
Research has indicated that during the inflammatory response to P. acnes, both the classical and the alternative complement pathways are activated. Which of the following are outcomes of activating complement pathways? Select all that apply.
-inflammation -opsonization -cytolysis
The hives that Sally is experiencing are a result of an anaphylactic reaction. This is a multistep reaction resulting from the interaction of the wasp venom and Sally's immune system. Each of the statements below is a step in the anaphylactic response.
1.IgE molecules bind to mast cells and basophils. 2. Antigen molecules cross-link adjacent IgE molecules. 3. Degranulation occurs. 4. Chemical mediators such as histamine are released. 5. Capillary permeability and smooth muscle contractions increase. 6. Neutrophils and eosinophils move to the site.
Some members of the normal microbiota can become opportunistic pathogens when given the proper conditions. One example given in the activity is the overgrowth of Clostridium difficile in an individual undergoing antibiotic therapy. Why might antibiotics increase the chances of an opportunistic infection by the normal microbiota?
Antibiotics that are nonspecific may affect pathogens as well as members of the normal microbiota.
The name Propionibacterium is derived from the fact that the organism produces propionic acid during fermentative metabolism. Which of the following statements about fermentative metabolism is true?
Fermentation produces significantly less ATP than aerobic respiration; however it generates NAD+, which can be used in glycolysis.
Which drug-resistance mechanism would most likely inactivate penicillin, a drug that targets cell wall synthesis?
Inactivation by enzymes
In this activity, you will identify the general mechanism of inhibition for the antimicrobial actions listed. Drag each item into the appropriate bin.
Inhibiting cell wall synthesis -Inhibiting bonding of N-acetyl glucosamine to N-acetylmuramic acid -Inhibiting synthesis of peptide cross-links -Inhibiting lypopolysaccharide synthesis -Inhibiting mycolic acid synthesis Injuring the plasma membrane -Inhibiting fatty acid synthesis Interfering with DNA replication -Interfering with Dna polymerase -Inhibiting DNA gyrase Interfering with RNA synthesis (transcription) -Interfering with RNA polymerase Interfering with protein synthesis -Interfering with activity of 30s ribosomal subunit -Interfering with activity of 50s ribosomal subunit -Interfering with attachment of tRNA to mRNA -Interfering with peptide bond formation, catalyzed by the ribosome
How would exposure to microbes treat Crohn's disease?
Microbes can suppress the action of inflammatory cytokines
