Phage DNA- he Phage Infects bactertal coll Donor coll- (Infacted by a virus) that Is hes. Host DNA Is digostad Into fragmonts, and phago DNA and proteins are made. his Phagas assemble; occasionally a phago carrles a fragment of the host cell chromosome. In this casa, It carrles the hts gane Transduction in bacteria. Genes+Traits During transduction, a phage carries a segment of bacterial DNA from a donor to a recipient cell. In this case, the phage carried a segment of DNA with the his+ gene and transferred this gene to a recipient cell that was originally his- (unable to synthesize histidine). Following transduction, the recipient cell became his+, and thus able to synthesize histidine. Transducing phage with host DNA Transducing phage Injects Its DNA into a recipient cell that Racombination his- Raciplent coll- The transduced DNA Is recombined Into the chromosome of the reciplent cell. his Recombinant bacterium The racombinant bacterium's genotype has changed from his- to his".

Phage DNA- he Phage Infects bactertal coll Donor coll- (Infacted by a virus) that Is hes. Host DNA Is digostad Into fragmonts, and phago DNA and proteins are made. his Phagas assemble; occasionally a phago carrles a fragment of the host cell chromosome. In this casa, It carrles the hts gane Transduction in bacteria. Genes+Traits During transduction, a phage carries a segment of bacterial DNA from a donor to a recipient cell. In this case, the phage carried a segment of DNA with the his+ gene and transferred this gene to a recipient cell that was originally his- (unable to synthesize histidine). Following transduction, the recipient cell became his+, and thus able to synthesize histidine. Transducing phage with host DNA Transducing phage Injects Its DNA into a recipient cell that Racombination his- Raciplent coll- The transduced DNA Is recombined Into the chromosome of the reciplent cell. his Recombinant bacterium The racombinant bacterium's genotype has changed from his- to his".

Biology: The Unity and Diversity of Life (MindTap Course List)

15th Edition

ISBN:9781337408332

Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Chapter20: Viruses, Bacteria, And Archaea

Section: Chapter Questions

Problem 3DAA: Bacteriophage-Inspired Antibiotics Although bacteriophages have been infecting bacteria for billions...

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An ade+ arg+ cys+ his+ leu+ pro+ bacterial strain is knownto be lysogenic for a newly discovered phage, but the siteof the prophage is not known. The bacterial map isleucysarghisadeproThe lysogenic strain is used as a source of the phage, andthe phages are added to a bacterial strain of genotypeade- arg- cys- his- leu- pro-. After a short incubation,samples of these bacteria are plated on six differentmedia, with the supplementations indicated in thefollowing table. The table also shows whether colonieswere observed on the various media.PresenceMedium Ade Arg Cys His Leu Pro of colonies1 - + + + + + N2 + - + + + + N3 + + - + + + C4 + + + - + + N5 + + + + - + C6 + + + + + - NNutrient supplementation in medium(In this table, a plus sign indicates the presence of anutrient supplement, a minus sign indicates that asupplement is not present, N indicates no colonies, and Cindicates colonies present.)a. What genetic process is at work here?b. What is the approximate locus of the prophage?
In the lysogenic cycle of bacteriophages, which of the fol-lowing is true?(a) Lysogeny is the term applied to a temperate phage thatdoes not replicate itself independently and does not lysethe bacterial host cell.(b) Phage DNA is incorporated into the host bacterium’sDNA, at which time it is called a prophage.(c) Temperate phages can be replicated either as a pro-phage along with bacterial chromosomal replicationor can suddenly revert to the lytic cycle by replicatingthemselves and assembling into new phages.(d) All the above are true.(e) a and c only.
Bacteriophage-Inspired Antibiotics Although bacteriophages have been infecting bacteria for billions of years, no mechanism, has evolved in bacteria to prevent the viruses from lysing the cell walls of their hosts. Now, scientists are targeting the same bacterial wall components that bacteriophages do. The goal is to develop antibiotics that bacteria will be less likely to develop resistance to. FIGURE 20.22 shows the results of a study to test Epimerox, a new bacteriophage-inspired antibiotic, against Bacillus anthracis, the bacterial species that causes the disease anthrax. FIGURE 20.22 Effect of Epimerox on the survival of mice with anthrax. Mice were infected with the bacteria B. anthracis. One group of 15 then began receiving a drug-free buffer solution 3 hours later. Another 15 were treated with Epimerox beginning 3 hours after infection. A third group of 15was treated with Epimerox beginning 24 hours after infection. In studies with Bacillus anthracis cells grown in culture, no Epimerox-resistant cells were observed. Explain why this result is consistent with the scientists' goal for developing this drug.
Bacteriophage-Inspired Antibiotics Although bacteriophages have been infecting bacteria for billions of years, no mechanism, has evolved in bacteria to prevent the viruses from lysing the cell walls of their hosts. Now, scientists are targeting the same bacterial wall components that bacteriophages do. The goal is to develop antibiotics that bacteria will be less likely to develop resistance to. FIGURE 20.22 shows the results of a study to test Epimerox, a new bacteriophage-inspired antibiotic, against Bacillus anthracis, the bacterial species that causes the disease anthrax. FIGURE 20.22 Effect of Epimerox on the survival of mice with anthrax. Mice were infected with the bacteria B. anthracis. One group of 15 then began receiving a drug-free buffer solution 3 hours later. Another 15 were treated with Epimerox beginning 3 hours after infection. A third group of 15was treated with Epimerox beginning 24 hours after infection. What do these data indicate regarding the optimal time to begin Epimerox treatment?
Host DNA is digested into small pieces, which are occasionally assembled with phage proteins, creating a phage with bacterial chromosomal DNA. If the breakage of the chromosomal DNA is not random (i.e., it is more likely tobreak at certain spots as opposed to other spots), how might suchnonrandom breakage affect cotransduction frequency?
If you extract the DNA of the coliphage φ X174, you willfind that its composition is 25 percent A, 33 percent T,24 percent G, and 18 percent C. Does this compositionmake sense in regard to Chargaff’s rules? How wouldyou interpret this result? How might such a phage replicate its DNA
If a single bacteriophage infects one E. coli cell present in a cultureof bacteria and, upon lysis, yields 200 viable viruses, howmany phages will exist in a single plaque if three more lytic cyclesoccur?
Decoding a DNA Message 2. AAT CTC CGA GCT TTG TAG TTA CCC ATT TAG AGT ATC TAG TTG TGT CTC GCT CTC AGG TGC TAT TTG CCT ACT
7. Replication factor C plays which of the following roles in eukaryotic DNA replication?A. the sliding clampB. the clamp loaderC. the DNA ligaseD. a single-stranded DNA binding proteinE. a cofactor required for activating the DNA polymerase 8. Phages that program the host cell for continued particle releasing without killing the cell are called ____________ phages.A. lyticB. lysogenicC. temperateD. chronicE. none of the above 9. Retroviruses use _______ to make a DNA copy of their RNA genome.A. restriction enzymesB. DNA polymerase IC. RNA polymerase IID. reverse transferaseE. reverse transcriptase
Experimentally, when an E. coli bacterium already has a λ prophageintegrated into its chromosome, another λ phage cannot usually infectthe cell and establish the lysogenic or lytic cycle. Based on yourunderstanding of the genetic regulation of the phage λ reproductivecycles, why do you think the other phage would be unsuccessful?
Decoding a DNA Message 1. CGA ACT AGA TAA CCC TTA TAG AAA TAT ACA CGC TTG TGA AAC ATA ATC CGG CTG CAA CGT TTA ACA CTC CTA ATT AGG ACA TAA CTC TTG ACA CTT ACT TAG AGA ACT CTC CGC TCA TAG GAG ATA ATT TAC TAA AGA TGA CGG TTT CTT TTG ACT CGA AGC ATT TAC CGC CCC TAG ATC 2. AAT CTC CGA GCT TTG TAG TTA CCC ATT TAG AGT ATC TAG TTG TGT CTC GCT CTC AGG TGC TAT TTG CCT ACT
19. An investigaor is conducting a study of n outbreak of severe nausea, vomitting and diarrhea among28 guests in a hotel. It is found that the affected guests stayed in rooms located in the east wing of the thrid floorof the hotel during a single3-week period. The causal virus most likely has which of the following chracteristics? (A) DNA genome (B) Helical symmetry (C) No envelope (D) No polymerase gene (E) Segmented genome