Inquizitive chapter 12

Why do scientists study bacteriophages?

Phages can make bacteria pathogenic. They interact with bacteria in all ecosystems. They are easy to grow and manipulate.

Which of the following statements correctly describe viruses?

Viral species can only infect a limited number of host species. Viruses are obligate intracellular pathogens.

Viruses are nature's minimalists. Because of their small genomes, they are very difficult to treat and eradicate. Which of the following are reasons why the small size of viral genomes poses difficulties for medical treatment?

Viruses mutate very rapidly. Antiviral drugs are difficult to discover. Antiviral medications often target host cell processes.

How might a virus evolve to infect a new species?

a genetic mutation in the spike protein a mutation that decreases the immune response

Viruses bind to receptors on host cell surfaces. What type of receptor does influenza virus bind?

a surface receptor found in many species

What is the name of the process that allows for a large change in a viral genome that potentially enables a virus to evade the immune system?

antigenic shift

There are more than 100 different strains of HPV. Which of the following determines the location on the human body that HPV infects?

cell-surface receptors

What term describes the range of tissue types a virus can infect?

tissue tropism

In which process does a virus transfer one host's genes to another host?

transduction

By what process do viruses induce carcinogenesis?

transformation

Why is agar needed in a plaque assay?

Agar keeps viruses from spreading to all the cells in the experiment.

In the United States, most sexually active people are infected with human papillomavirus.

True

Where on this curve are progeny virions being assembled?

Eclipse Period

Reverse transcriptase is an enzyme made by RNA viruses to transcribe their genome to messenger RNA.

False

Small RNA viruses are commonly phagocytosed by cells.

False

Why do small viral genomes produce many proteins?

Genes are expressed in overlapping reading frames.

Gardasil protects against which virus?

HPV

Which parts of the HIV life cycle are targets/potential targets for antiviral drugs?

The HIV virion attaches (1) The vision fuses to the membrane and releases its core in the cytoplasm.(2) The core dissolves, and the RNA chromosomes are copied/replaced to make double-stranded DNA (3) The viral DNA integrates in a host chromosome (5) Viral RNA transcripts express capsid and reverse transciptase proteins(7) The membrane-embedded Env proteins assist the packaging of the RNA dimers plus Gag-Pol peptides into the core.(11) *If spike proteins bind to CD4 and CCR5 receptors of a neighboring cell, cell fusion allows core particles to enter a new cell.

Viral genomes can be encoded by RNA or DNA.

True

Viruses have characteristics of both living and nonliving things.

True

Viruses that integrate into the host cell chromosome have the potential to cause cancer.

True

Match each antiretroviral medication to the part of the HIV life cycle that it targets

The virion fuses to the cell membrane and releases its core into the cytoplasm. Correct label: enfuvirtide The HIV virion attaches to receptors in the cell membrane. Correct label: maraviroc Viral RNA transcripts express capsid and reverse transcriptase proteins. Correct label: protease inhibitors The core dissolves, and the RNA chromosomes are copied/replaced to make double-stranded DNA. Correct label: AZT Correct label: emtricitabine Correct label: tenofovir The viral DNA integrates in a host chromosome. Correct label: raltegravir (Page 390)

What causes the sudden appearance of new pandemic influenza virus strains?

genetic reassortment between different influenza viruses close interaction between birds, swine, and humans in live animal markets (wet markets)

When growing viruses in the lab, you also need which of the following items?

host cells

Suppose a virus is able to infect chimpanzees but no other great apes. What is the chimpanzee called in regards to this species of virus?

host range

Which of these common viruses contains a segmented genome?

influenza virus

Which viral genes are responsible for transforming cells?

oncogenes

What is the name for the double-stranded DNA copy of a retroviral genome that integrates into the host genome?

provirus

Place the events in the order in which most viruses infect cells (not all choices may be used).

recognize and attach to the host cell genome entry genome replication progeny virion assembly virion exit and transmission

Viruses evolve rapidly in part because of the error-prone nature of their replication enzymes, but not all viruses evolve at the same rate. Which of these viruses have a high rate of genetic mutation and adaptation?

retroviruses segmented viruses

All retroviruses contain genes for which of the following?

reverse transcriptase capsid envelope

Retroviruses rely on these enzymes to integrate their genome into the host chromosome.

reverse transcriptase integrase

Viral capsids are highly complex structures but are only formed using a small number of proteins. What geometric feature allows viral capsids to be formed from so few proteins?

symmetrical

The Baltimore model is used to classify a virus based on which aspects of its life cycle?

whether it is single or double stranded whether it has a DNA or RNA genome how it makes its messenger RNA (mRNA)

Match the examples with the levels of virus evolution

within a host community Correct label: equine herpes versus murine herpes within a viral species population Correct label: herpes simplex 1 and herpes simplex 2 Correct label: varicella-zoster versus cytomegalovirus within an individual organism Correct label: hepatitis C and HIV