LSU BIOL 1202 (HRINCEVICH) CH. 27 HW

Because bacteria reproduce asexually, each organism typically obtains its genetic material from only one parent. However, bacteria do have mechanisms for bringing together DNA from different individuals. One of these mechanisms is bacterial conjugation, a process that results in the direct transfer of genetic material from one bacterium to another. The figure shows two examples of bacterial conjugation. In these examples, bacteria with a segment of DNA called an F factor are able to initiate conjugation. An F factor is a piece of DNA that contains about 25 genes. Most of the genes in the F factor are related to the production of a structure called a mating bridge. The mating bridge links two bacterial cells during conjugation, allowing for DNA transfer. The F factor may be found on a separate piece of DNA called an F plasmid, shown in part (a) of the figure. Or it may be found within the main bacterial chromosome, shown in part (b) of the figure. Drag each phrase into the appropriate bin depending on whether it applies to an F+ cell, an Hfr cell, or an F- cell. (Remember that we are only considering conjugation involving the F factor here, and not other mechanisms for transferring genetic material.)

F+ cell: - carries the F factor in a plasmid - may donate a plasmid to another cell Hfr cell: - carries the F factor in its circular chromosome - may donate genes from its chromosome to another cell F- cell: - may become F+ after conjunction with an F+ cell - may receive genetic material, but cannot donate genetic material - may become recombinant after conjunction with an Hfr cell

Organisms that can cause nongonococcal urethritis are classified with _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

b. chlamydias

Which of the following typically produces a recombinant F+ recipient cell? a. conjugation between two Hfr cells b. conjugation between an F+ cell and an F- cell c. conjugation between an Hfr cell and an F- cell d. conjugation between two F- cells

b. conjugation between an F+ cell and an F- cell

Based on your results in Part A, which of the following statements most appropriately reflects the relative effectiveness of the vancomycin treatment, teixobactin treatment, and the control? a. Teixobactin was significantly more effective than the vancomycin at reducing the number of MRSA colonies relative to the control. b. Teixobactin was significantly less effective than the vancomycin at reducing the number of MRSA colonies relative to the control. c. Teixobactin reduced the number of MRSA colonies about as effectively as did vancomycin relative to the control. d. Neither teixobactin or vancomycin were effective at reducing the number of MRSA colonies relative to the control.

c. Teixobactin reduced the number of MRSA colonies about as effectively as did vancomycin relative to the control.

Spiral-shaped bacteria are likely to be placed with _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

c. spirochetes

The figure shows how bacteria reproduce through binary fission. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. 1. Binary fission is a form of _________ because a single individual is the sole parent and passes copies of all its genes to its offspring. 2. During binary fission, DNA replication begins at the __________ and continues all the way around the circular chromosome. 3. When DNA replication is complete and the bacterium has reached twice its original size, the __________ grows inward, dividing the parent cell into two daughter cells. 4. In theory, the two daughter cells are _________ each other and the parent cell. 5. However, mistakes made during DNA replication sometimes result in _________ , changes to the nucleotide sequence of DNA. 6. The rapid reproduction and large population sizes of many bacterial populations mean that even a small mutation rate can lead to considerable _________.

1. asexual reproduction 2. origin of replication 3. plasma membrane 4. genetically identical to 5. mutations 6. genetic variation

True or false? Data showing that the Bacteria were the first lineage to diverge from the common ancestor of all living organisms suggest that the Archaea and Eukarya are more closely related to each other than they are to the Bacteria.

True

What is the difference between an F+ donor and an Hfr donor? a. The Hfr donor has an F factor integrated into its main chromosome, but the F+ donor does not. b. The Hfr donor has an F factor, but the F+ donor does not. c. The Hfr donor has an F plasmid, but the F+ donor does not. d. The F+ donor has an F factor, but the Hfr donor does not.

a. The Hfr donor has an F factor integrated into its main chromosome, but the F+ donor does not.

Which statement is true about obligate anaerobes? a. They are poisoned by O2. b. They will use O2 if it is present, but can obtain energy by fermentation if needed. c. They use O2 for cellular respiration and cannot grow without it. d. They live exclusively by cellular respiration or by anaerobic respiration. e. They obtain energy by oxidizing ferrous ions.

a. They are poisoned by O2.

The asexual reproduction of bacteria described in the Part A figure may seem to suggest that all bacterial cells within a population should be the same. Yet bacterial populations possess considerable genetic variation. You have seen that two significant sources of genetic variation in bacteria are: mutations that arise during DNA replication genetic exchange during bacterial conjugation Genetic variation has allowed many bacteria to evolve resistance to antibiotics, and conjugation plays a particularly important role in the spread of antibiotic resistance from one bacterial species to another. Like the F plasmid, the R plasmid (R stands for "resistance") may allow bacteria to initiate conjugation. The R plasmid contains genes for antibiotic resistance. During conjugation, the R plasmid and its antibiotic-resistance genes are transferred from the donor cell to the recipient cell. The graph below shows how antibiotic resistance can develop in a patient with a bacterial infection. Notice that the bacteria count drops when antibiotic therapy is started, but then rises again as resistance spreads through the population. Drag the labels to their appropriate locations on the concept map below to explore the links between antibiotic resistance, binary fission, and conjugation.

a. antibiotics b. antibiotic resistance c. binary fission d. conjugation e. mutations f. DNA replication g. genetic recombination h. genetic variation

Which of the following could cause DNA from the main chromosome of a donor cell to be incorporated into the main chromosome of the recipient cell? a. conjugation between an Hfr cell and an F- cell b. conjugation between two F+ cells c. conjugation between two F- cells d. conjugation between an F+ cell and an F- cell

a. conjugation between an Hfr cell and an F- cell

The chemoheterotroph Proteus vulgaris is a rod-shaped bacterium classified with _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

a. proteobacteria

An ecological relationship between organisms of different species that are in direct contact can best be described as _____. a. symbiotic b. commensal c. taxis d. parasitic e. mutualistic

a. symbiotic

Which of the following statements best represents the effectiveness of teixobactin and vancomycin in reducing the number of MRSA colonies relative to the control? a. At both treatment doses, vancomycin was significantly more effective at reducing the number of MRSA colonies than both teixobactin and the control. This suggests that vancomycin, not teixobactin, should be used to treat MRSA. b. Both antibiotics substantially reduced the number of MRSA colonies compared to the control. Further, at both the 1 mg/kg and 5 mg/kg doses, there was no significant difference in the number of MRSA colonies, suggesting that teixobactin and vancomycin are equally effective at controlling MRSA. c. At both treatment doses, teixobactin was significantly more effective at reducing the number of MRSA colonies than both vancomycin and the control. This suggests that teixobactin, not vancomycin, should be used to treat MRSA. d. At the 5 mg/kg dose, both teixobactin and vancomycin substantially reduced the number of MRSA colonies compared to the control; however, at the 1 mg/kg dose, the number of MRSA colonies was not significantly different from the control. This suggests that the antibiotics are not effective at low doses.

b. Both antibiotics substantially reduced the number of MRSA colonies compared to the control. Further, at both the 1 mg/kg and 5 mg/kg doses, there was no significant difference in the number of MRSA colonies, suggesting that teixobactin and vancomycin are equally effective at controlling MRSA.

Which statement about endotoxins is true? a. The source of endotoxins is endospores. b. Endotoxins are released only when bacteria die and their cell walls break down. c. An example of a prokaryote that produces endotoxins is Clostridium botulinum. d. Endotoxins are proteins secreted by prokaryotes. e. Endotoxins are components of the cell wall of gram-positive bacteria.

b. Endotoxins are released only when bacteria die and their cell walls break down.

What characteristics were used to classify organisms before Woese's tree of life analysis? a. Number of cells in the organism b. Presence of a membrane-bound nucleus c. Differences in ribosomal RNA sequences d. Composition of the cell wall

b. Presence of a membrane-bound nucleus

Which group was not described in Woese's tree of life analysis? a. Eukarya b. Prokarya c.Bacteria d. Archaea

b. Prokarya

Which molecule did Carl Woese study to produce his tree of life? a. Ribosome b. Ribosomal RNA d. DNA e. Messenger RNA

b. Ribosomal RNA

Suppose conjugation occurs between an Hfr cell and an F- cell. Although not typical, what would have to occur for the recipient cell to become an Hfr cell? a. A portion of the F factor would have to be incorporated into the recipient cell's chromosome. b. The entire F factor would have to be incorporated into the recipient cell's chromosome. c. A portion of the F plasmid would have to be transferred to the recipient cell. d. The entire F factor would have to be transferred to the recipient cell.

b. The entire F factor would have to be incorporated into the recipient cell's chromosome.

Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____. a. photoautotrophs b. chemoautotrophs c. photoheterotrophs d. chemoheterotrophs

b. chemoautotrophs

Finally, let's calculate the standard error (SE) for each treatment using the following formula: SE=s/√n. In this formula, s is the standard deviation of each treatment, and n is the number of observations in each treatment. Drag the standard error values to the last column of the table.

control: 0.14 vancomycin: 0.09 3rd drug: 0.35 Teixobactin: 0.71 5th drug: 0.31

Now that you have a mean value for each treatment, it's important to examine the variation around that mean. To do so, calculate the standard deviation for each treatment using the following formula: s=√1/n−1Σ(xi−x¯)2. Drag the standard deviation values to the last column of the table.

control: 0.27 vancomycin: 0.15 3rd drug: 0.6 Teixobactin: 1.42 5th drug: 0.62

Mean values can be calculated using the following formula: x¯=Σxi/n. In this formula, x i is the value of the ith observation of the treatment variable x, n is the number of total observations, and the Σ symbol indicates that the n values of x are to be added together. Calculate the mean for each treatment. Drag the correct values to the appropriate locations in the table.

control: 9.1 Vancomycin: 8.4 3rd drug: 5.3 Teixobactin: 7.2 5th drug: 4.7

Which of the following statements about phylogenetic trees is true? a. A paraphyletic group has not experienced lateral gene transfer. b. A paraphyletic group consists of an ancestral population and all of its descendants. c. A monophyletic group consists of a common ancestor and some of its descendants. d. A paraphyletic group consists of a common ancestor and some of its descendants.

d. A paraphyletic group consists of a common ancestor and some of its descendants.

According to this phylogenetic tree, which of these pairs of prokaryotic subgroups share the most recent common ancestor? a. Euryarchaeota ... Cyanobacteria b. Proteobacteria ... Crenarchaeota c. Proteobacteria ... Euryarchaeota d. Euryarchaeota ... Crenarchaeota e. Crenarchaeota ... Cyanobacteria

d. Euryarchaeota ... Crenarchaeota

What is lateral gene transfer? a. Inheritance of a gene through mitosis b. Inheritance of a gene through meiosis c. Inheritance of a gene from a parent d. Physical transfer of a gene from a species in one lineage to a species in another lineage.

d. Physical transfer of a gene from a species in one lineage to a species in another lineage.

What usually happens to the recipient cell following conjugation with an Hfr cell? a. The recipient cell becomes an Hfr cell. b. The recipient cell remains an F+ cell. c. The recipient cell may become either an F+ or an Hfr cell. d. The recipient cell remains an F- cell.

d. The recipient cell remains an F- cell.

Streptococcus pyogenes is classified with _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

d. gram-positive bacteria

What is the function of fimbriae? a. They protect the cell from dehydration. b. They are used in motility. c. They are used to transfer DNA during conjugation. d. They are components of the outer cell wall in gram-negative bacteria. e. They are used to attach the cell to its substrate or to other prokaryotes.

e. They are used to attach the cell to its substrate or to other prokaryotes.

The prokaryotic cells that built stromatolites are classified as _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

e. cyanobacteria

The prokaryotic cells that were the first to add significant quantities of oxygen to Earth's atmosphere are classified as _____. a. proteobacteria b. chlamydias c. spirochetes d. gram-positive bacteria e. cyanobacteria

e. cyanobacteria

The prokaryotic organisms most likely to be found living in salt ponds are the _____. a. methanogens b. Korarchaeota c. thermophiles d. extremophiles e. halophiles

e. halophiles

Bioremediation is _____. a. the modification of prokaryotes for industrial purposes b. the use of prokaryotes in producing pharmaceutical products c. the use of biological processes to remedy diseases d. the use of prokaryotes in producing transgenic organisms e. the use of organisms to remove pollutants from the environment

e. the use of organisms to remove pollutants from the environment

The standard error that you calculated in Part D indicates how greatly the mean would likely vary if the experiment were repeated. If repeated, the new mean would typically lie within two standard errors of the original mean (that is, within the range x¯x¯ ± 2SE). This range provides a rough but useful indication of whether two means differ from one another. For example, if the interval surrounding the mean for one treatment overlaps the interval surrounding the mean for another treatment, this would suggest that the two means were approximately equal and hence that the treatments from which the means were calculated were roughly similar in their overall effect. The x¯x¯ ± 2SE values have been computed for you and are provided in the table. Select the graph that best represents the data provided in the table.

graph with control first on the x-axis and small standard deviation bars