Concept explainers
Introduction:
Bacterial cells can be classified as gram-positive or gram-negative, depending upon the ability to retain the stain. The gram-positive bacteria have a thick layer of peptidoglycan, while the gram-negative bacteria have a thin layer of peptidoglycan cell-wall. The crosslinking of a peptidoglycan in gram-positive bacteria helps it retain the crystal violet stain (
Answer to Problem 1TYK
Correct answer:
Pili keep them attached to the urethral walls.
Explanation of Solution
Explanation/justification for the correct answer:
Option (d) is pili. Pili are the hair-like structures that arise from the cell walls of the bacteria. Pili are mostly present in gram-negative bacteria and help them adhere to a surface like other prokaryotic cells or tissue membranes like the urethral lining in humans. Hence, option (d) is the correct answer.
Explanation for incorrect answer:
Option (a) is sex pili. The sex pili are extended for conjugation, in which the one bacterium exchanges genetic material with another, under adverse conditions. Sex pili do not help in adherence to the host tissues. So, it is an incorrect option.
Option (b) is flagella. Flagella are hair-like extensions that help in the locomotion of a microbe. The flagella move with the help of motor proteins, allowing the bacteria to move from one location to another. So, it is an incorrect option.
Option (c) is capsule. The capsule is a diffused glycocalyx present in the gram-negative bacteria. It protects the bacteria from antibiotic effects. The peptidoglycan of cell-wall protects the bacteria from adverse environments. So, it is an incorrect option.
Therefore, it can be concluded that the bacterial cells that are present in the urethra are gram-negative as their surface is covered with pili that help them adhere to the urethral walls.
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Chapter 26 Solutions
Biology: The Dynamic Science (MindTap Course List)
- You 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_forwardWhy 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_forward
- You 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_forwardis often a good indication of phylogenetic relatedness in phenotypes. Life-cycle patterns Cleavage patterns O Gene expression O Morphological similarityarrow_forward
- Which 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_forwardWhat is the most appropriate purpose of building a phylogenetic tree? They look awesome You can use a tree to compare morphological characteristics of organisms It can be used to establish and analyze evolutionary relationships between species All of the abovearrow_forward
- Which of the following sequencing techniques can identify down to the strain level? O Multilocus sequence typing Genomic fingerprinting Whole genome sequencing OSNP analysis All of the abovearrow_forwardWhat is the "gold standard" that is currently applied to species designations in microbiology? 97% between species: 50% among whole genome 90% between species: 75% among whole genome 99% between species; 97% among whole genome 97% between species: 70% among whole genome Onone 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 decided to send your sample off for sequencing. You need to determine which type of sequencing to use for the preliminary identification of your species. You decide that, for now, you only need to be able to identify the family and genus levels. Which type of sequencing do you think is the most appropriate? O Genomic Fingerprinting O Whole Genome Sequencing O 16S rDNA Sequencing O DNA-DNA hybridization Nextarrow_forward
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