Many virologists note that viruses which have a genome made up of RNA will tend to evolve faster than those viruses whose genome is made up of double-stranded DNA. Most evolutionary biologists now accept that RNA was the first nucleic acid molecule to evolve to store information. Why is this early “RNA world” more likely when you consider how RNA polymerases (such as primase) and DNA polymerases start replicating nucleotide chains?

You are studying RNA viruses and have discovered a new one that grows well in a culture of eukaryotic cells. You know that the virus is a single-stranded RNA virus, but you don’t know if it is plus or minus stranded. Your lab-mate says, “Well, just treat your cell culture with cyclohexamide and see if the virus replicates its genome.” You know that cyclohexamide inhibits protein elongation by binding to eukaryotic ribosomes. What is the basis of your lab-mate’s suggestion?

You are studying RNA viruses and have discovered one that grows well in a culture of eukaryotic cells. You know that the virus is a single-stranded RNA virus, but you don't know if it is positive or negative stranded. Your lab-mate says, "Well, just treat your cell culture with cyclohexamide and see if the virus replicates its genome." You know that cyclohexamide inhibits protein elongation by binding to eukaryotic ribosomes. What is the basis of your lab-mate's suggestion?

Which of the following statements most accurately describes the action of the enzyme RNA polymerase?Select one  1.) RNA polymerase will transcribe only the exons by skipping over the introns within a eukaryotic gene sequence 2.) RNA polymerase will transcribe both DNA strands, moving in the 3' to 5' direction for one strand and 5' to 3' on the other 3.) RNA polymerase will transcribe both DNA strands, but only one RNA molecule will be used during translation 4.)None of the statements accurately describe the function of RNA polymerase

For many years, scientist believed that proteins were the source of heritable information. There are many thousands of different proteins in a cell, and they mediate the cell’s metabolism, producing the traits and characteristics of a species. Researchers working with DNA viruses proved that it is DNA that stores and passes on genes. They worked with viruses with an outer coat of protein and a DNA strand inside. How did they prove that it was DNA, not protein, which is the primary source of heritable information?

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.

Viruses are made up of the same biomolecules as cellular organisms (DNA, RNA, proteins, lipids, etc.), which are synthesized through enzymatic dehydration reactions from building blocks and disassembled by enzymatic hydrolysis. They infect cells and replicate themselves using resources from the host cells. Scientists discovered a previously unknown strain of virus in the tropical Pacific Ocean and it can infect higher-order eukaryotes. Initial analysis revealed that the virus is mainly composed of nucleic acids, proteins, and lipids. Chemical analysis after complete hydrolysis revealed the following building blocks (by weight): Chemical components Nucleosides Amino acids Lipids, phosphates, and carbohydrates Percentage by weight 20 30 50 Analysis of percentages of nucleosides yielded the following results (by molar ratio): Nucleosides A G T C U Percentage by mole 19 29 19 29 4 Which of the following events mostly involves hydrolysis reaction after the virus infects…

Bacteria exposed to viruses incorporate sections of the virus’s DNA into the CRISPR array sequences in their genome. This mechanism allows bacteria to fight off the viruses, like an immune response: the information in CRISPR spacers served as “coordinates” for recognizing and cutting up invading DNA sequences. Describe what might happen under the conditions described after a bacteriophage infects a bacterial cell and releases its DNA into the bacterial cell.   Explain why: 1. The invading phage DNA is recognized by the Cas proteins but not inserted into the CRISPR array region of the bacterial genome: The bacteria will be unable to elicit an immune response and will succumb to the phase infection 2. The cas genes on the bacterial genome contains a missense mutation that increases its cleavage/cut activityThe bacteria will elicit an immune response that will successfully fight the phage infection

You are a virologist studying a newly isolated viral strain and have sequenced its genome. You find that the genome contains 25% A, 55% G, 20% C, and 10% U. Which of the following conclusions is likely correct? This is a single-stranded RNA virus   This is a single-stranded DNA virus   This is a double-stranded RNA virus   This is a double-stranded DNA virus   No conclusions can be drawn from this information

The virus causing the 2009 Flu Pandemic contained sequences from bird, pig, and humans. Why? The infected individuals happened to be infected with all three virus types. The human was likely infected with various bacterial strains that contained all three RNA viruses. The virus was descended from a common ancestor of bird, pig, and human flu viruses. Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly.