Why must primary cell cultures be restarted every so often when preparing primary cell cultures to observe morphological changes caused by cells infected by a virus? Why are tumor cells preferred? Why are non-enveloped viruses generally more resistant to disinfectants than are enveloped viruses? A public health physician isolated large number of phages from rivers used as a source of drinking water in western Africa. They physician is very concerned that humans might become ill from drinking this water, although she knows that the phages specifically attack bacteria. Why is she concerned?

Why must primary cell cultures be restarted every so often when preparing primary cell cultures to observe morphological changes caused by cells infected by a virus? Why are tumor cells preferred? Why are non-enveloped viruses generally more resistant to disinfectants than are enveloped viruses? A public health physician isolated large number of phages from rivers used as a source of drinking water in western Africa. They physician is very concerned that humans might become ill from drinking this water, although she knows that the phages specifically attack bacteria. Why is she concerned?

Biology Today and Tomorrow without Physiology (MindTap Course List)

5th Edition

ISBN:9781305117396

Author:Cecie Starr, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Christine Evers, Lisa Starr

Chapter10: Biotechnology

Section: Chapter Questions

Problem 2CT

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In 2006, the US Food and Drug Administration (FDA) approved the use of bacteriophage preparation that can be used on ready-to-eat meat and poultry products to kill Listeria monocytogenes, a bacterium that causes listeriosis. Some people may have concerns about the use of phages in foods. From what you have learned about bacteriophages and viruses, why do you think we do not have to be concerned about the presence of bacteriophages in food?
Assume you isolate a single stranded (+) RNA virus. When you examine the proteins in the virus, you find that it does NOT contain replicase enzymes within its capsid. Which of the following is true? This virus must have a gene that encodes replicase. This virus will not be able to enter a host cell. Its genome cannot be translated (the process of translation) by the host cell ribosomes. A DNA copy of the viral genome has to be made before viral genes are expressed. This virus must lack surface antigens.
Which biological system contains a protein nucleocapsid surrounding 2 antiparallel polynucleotide strands (held together by hydrogen bonds), with deoxyribose sugars, but no ribose sugars? a single-stranded RNA viroid (like avocado sun blotch viroid) a double-stranded RNA virus (like the reovirus family) a single-stranded DNA virus (like fX174 virus of E. coli) a double-stranded DNA virus (like the smallpox virus) a single-stranded RNA virus (like tobacco mosaic virus)
Imagine that you are a student in Alfred Hershey and Martha Chase’s lab in the late 1940s. You are given five test tubes containing E. Coli bacteria infected with T2 bacteriophages that have been labeled with either 32P or 35S. Unfortunately, you forget to mark the tubes and are now uncertain about which tubes is which. You performed their blender experiment and got the following results. Which tube out of these 5 contains E. Coli infected with 32P-labeled phage? Explain your answer.
In 1918, an influenza pandemic that originated with avian flu killed 50 million people. Researchers isolated samples of that virus from bodies of infected people preserved in Alaskan permafrost since 1918. From the samples, they sequenced the viral genome, then reconstructed the virus. The reconstructed virus is 39,000 times more infectious than modern influenza strains, and 100 percent lethal in mice. Understanding how this virus works can help us defend ourselves against other deadly influenza strains that arise. For example, discovering what makes it so infectious would help researchers design more effective vaccines. Critics of the research are concerned: If the virus escapes the containment facilities (even though it has not done so yet), it might cause another pandemic. Worse, terrorists could use the published DNA sequence and methods to make the virus for horrific purposes. Do you think this research makes us more or less safe?
About the technique of phage display: MOLECULAR BIOLOGY_advanced The Escherichia coli cell infected by the phage codifies for the optimized ligand when the phage DNA integrates in the DNA of the bacteria. Phages are selected if they express on their surface the optimized ligand. One selects Escherichia coli cells that are resistant to the phage infection. More than one optimized ligand can be selected during the panning procedure. The ligand to be selected on the surface of the phage is non-covalently linked to one of the surface proteins.
Which of the following is a known characteristic or procesds that can lead to genetic changes in some viruses? When two different viral strains of the same type of virus infect a single individual, reassortment/mixing of segmented genome pieces can occur, resulting in new combinations of segments. Genetic rearrangements of the viral genome occurs as a result of duplicate operons in the viral genome undergoing homologous recombination. Environmental conditions trigger the SOS response in viruses, and leads to generation of errors/mutations in the viral genome. Viral RNA polymerases display proofreading capability in replicating the viral genome of certain viruses.
One of the reasons why phage therapy has not been applied widely is that bacteria can become resistant to bacteriophages as well, through mutations in genes encoding for specific proteins. What would be a protein in the bacterial cell that, if mutated, would make that cell resistant to phage infection?
1 mL of a bacteriophage suspension is mixed with 20 mL of a bacterial culture and 50% of the phages adsorb. We know that the bacteriophage suspension had a concentration of 1x1010 viruses per mL, and the bacterial culture had a concentration of 3x108 bacteria per mL. What fraction of the cells is multiple infected?
According to Philip Bell’s viral eukaryogenesis hypothesis, genes for DNA replication, RNA transcription, protein translation, and histone proteins were all provided by: an endosymbiotic gram-negative eubacterium an endosymbiotic archaeobacterium a gram-positive eubacterial host cell a double-stranded DNA virus an archaeobacterial host cell
Arrange the following list into the correct sequence for part of the cycle of a retrovirus: 1. dsDNA integrated into host DNA 2.viral proteins synthesized on host ribosomes 3. viral DNA uses host enzymes to transcribe viral RNA 4. reverse transcriptase catalyzes synthesis of ssDNA 5. synthesis of second DNA strand (a) 5, 2, 1, 3, 4 (b) 5, 2, 3, 4, 1 (c) 4, 5, 1, 3, 2 (d) 4, 1, 2, 3, 5 (e) 2, 1, 3, 4, 5
Some mutations that occur in bacteria can cause the loss of phage receptors, and these bacteria become phage resistant. In order for a phage to infect the host bacterium, it is preferred that the cell wall is newly synthesized.why ?