Concept explainers
Videos
Unwelcome Dinner Guests
How do harmful bacteria get into our food? Marty foodborne illnesses result from consumption of contaminated beef. The intestinal tracts of about a third or the cattle in the United States carry bacteria that are harmful to humans, and these bacteria can be transmitted to humans when a meatpacker accidentally grinds some gut contents into hamburger. Similarly, chicken feces may splash onto eggs, setting the stage for harmful bacteria to enter the eggs through tiny cracks or when the consumer breaks the egg and its contents contact the shell. Produce such as lettuce, spinach, tomatoes, and melons can also become contaminated if farm fields are exposed to animal feces, which can be deposited by deer or wandering domestic animals or carried from nearby ranches and feedlots in dust or runoff. The warm, moist environments in which sprouts are grown provide excellent growing conditions for any harmful bacteria that may have been present on the seeds from which the sprouts were produced.
How can you protect yourself from the bacteria that share our food supply? It's easy: Clean, cook, and chill. Cleaning helps prevent the spread or pathogens. Wash your hands before preparing food, and wash all utensils and cutting boards after preparing each item. Thorough cooking is the best way to ensure that any bacteria present in food are killed. Meats, in particular, must be thoroughly cooked; food safety experts recommend using a meat thermometer to ensure that the thickest part of cooked pork or ground beef has reached 16CTF. The safe temperature for cuts or beef, veal, or lamb is 145°F; for all poultry, 165°F. The color or cooked meat can be an unreliable indicator of safety, but when a meat thermometer is unavailable, try to avoid eating meat that is still pink inside, especially ground beef. Fish should be cooked until it is opaque and flakes easily with a fork; cook eggs until both white and yolk are firm. Finally, keep stored food cold. Pathogens multiply most rapidly at temperatures between 4CT and 140CF. So get your groceries home from the store and into the refrigerator or freezer as quickly as possible. Don’t leave cooked leftovers unrefrigerated for more than 2 hours. Thaw frozen foods in the refrigerator or the microwave, not at room temperature. A little bit of attention to food safety can save you from unwelcome guests in your food.
CONSIDER THIS Consumer groups contend that we can improve food safety by giving government agencies additional funding and greater authority to inspect rood processing plants and order recalls of contaminated food. Opponents or such steps argue that we need not empower government agencies because the best protection against rood contamination is informed consumers, who will stop buying products from companies that have produced unsafe foods. Would you support or oppose additional government oversight of food safety?
Want to see the full answer?
Check out a sample textbook solution
Chapter 20 Solutions
Biology: Life on Earth with Physiology (11th Edition)
- Overview of Transformation Protocol -Prepare competent bacteria for transformation: Treat starter E. coli bacteria with CaCl2and Competent Cell Solution (CCS). Store on ice until transformation procedure. Competent cells are cells that are likely to take up foreign DNA and be transformed. This step increases the likelihood that the E. coli cells will take up the introduced vector and be transformed. -Transformation procedure: Obtain two microcentrifuge tubes containing your competent cells. Label one tube +DNA and one -DNA. Add CaCl2 to both tubes. Add the transformation mix containing the plasmid DNA to the tube labeled +DNA. Do not add any plasmid DNA to the -DNA tube. Incubate both tubes on ice for 10 minutes. Then, place both tubes in a 42\deg C water bath for 45 seconds. Replace the tubes in an ice bucket for 2 minutes. Add recovery broth to both tubes. Incubate both tubes in a 37 C water bath for 5 minutes. Questions: 1) What differences would you expect to see between the…arrow_forwardOverview of Transformation Protocol -Prepare competent bacteria for transformation: Treat starter E. coli bacteria with CaCl2and Competent Cell Solution (CCS). Store on ice until transformation procedure. Competent cells are cells that are likely to take up foreign DNA and be transformed. This step increases the likelihood that the E. coli cells will take up the introduced vector and be transformed. -Transformation procedure: Obtain two microcentrifuge tubes containing your competent cells. Label one tube +DNA and one -DNA. Add CaCl2 to both tubes. Add the transformation mix containing the plasmid DNA to the tube labeled +DNA. Do not add any plasmid DNA to the -DNA tube. Incubate both tubes on ice for 10 minutes. Then, place both tubes in a 42\deg C water bath for 45 seconds. Replace the tubes in an ice bucket for 2 minutes. Add recovery broth to both tubes. Incubate both tubes in a 37 C water bath for 5 minutes. Questions: 1)What is the selectable marker in this experiment? How…arrow_forwardBased on your results, which suspect's DNA best matches the DNA found at the crime scene?arrow_forward
- In oxidase test with Pseudomonas aeruginosa, the cell cultures on the slide turn colorless to be purple after tetra-methyl-p-phenylenediamine dihydrochloride (TMPD) is added. In the reaction, OTMPD is electron acceptor O cytochrome c is the electron source oxygen is terminal electron acceptor OH2 produced is electron donorarrow_forwardYou will use the following scenario to answer a group of 5 questions. You have isolated a microbe from an environmental sample. The microbe has the ability to perform a new metabolic reaction at a very low temperature, so you are excited that it could be a new species. You have shipped your samples off for sequencing and are now waiting for the results. Out of curiosity (and maybe boredom...) you decide to test your culture for the Catalase and Oxidase enzymes. Upon testing your sample for catalase, you don't see any bubbles; however, you do see a color change to purple during the Oxidase test. What results can you conclude from this? O Catalase-/ Oxidase + O Catalase +/ Oxidase + Catalase + / Oxidase- O Catalase / Oxidase - O None of the abovearrow_forwardWhich of the following is not a strength of using 16S rRNA for phylogenetic analyses? OA. It's cheap OB. It's easy to do C. It can be used to identify all the way down to the strain level OD. Both A & B OE. None of the abovearrow_forward
- Why are molecular approaches important to the field of microbial taxonomy and phylogeny? Phylogenetic inferences based on molecular approaches provide the most robust analysis of microbial evolution currently available. It allows for the collection of a large and accurate dataset from many organisms Almost no fossil record was left by microbes when compared to plants and animals All of the above None of the abovearrow_forwardYou will use the following scenario to answer a group of 5 questions. You have isolated a microbe from an environmental sample. The microbe has the ability to perform a new metabolic reaction at a very low temperature, so you are excited that it could be a new species. You have already cultured it and gone through the plate isolation procedure. Before you ship your samples off for sequencing, you want to do one final check of the A260 ratios. You get back the following ratios: A260/280 ratio is 1.89; A260/230 is 2.01. These ratios are close enough to the accepted "pure" values so they could be considered "pure" and mostly (if not completely) free of contaminants from the PCR process. True Falsearrow_forwardYou will use the following scenario to answer a group of 5 questions. You have isolated a microbe from an environmental sample. The microbe has the ability to perform a new metabolic reaction at a very low temperature, so you are excited that it could be a new species. After receiving your sequence back from the sequencing lab, you feel that you have, in fact, discovered and isolated a new species. You ask a fellow labmate about how you should proceed, and he tells you the following is the proper way to introduce a new species for recognition: Cultures have to be sent to international culture collections. Then a paper must be published describing the new organism and providing a genus and species name. You recall learning about this in your Microbiology course in college. Is this information from your colleague true or false? True Falsearrow_forward
- is often a good indication of phylogenetic relatedness in phenotypes. Life-cycle patterns Cleavage patterns O Gene expression O Morphological similarityarrow_forwardWhich of the following is a weakness of using 16S rRNA for phylogenetic analyses? It can only go down to the family and genus levels It takes months to complete O Both of the above O None of the abovearrow_forwardAn unrooted tree containing ten unrelated species can become rooted by adding a descendant group related to two of the species. an unrelated outgroup. O a distantly related outgroup. O a descendant related to only one of the species.arrow_forward
Biology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStax
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning
Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning