Question

Name: Extra Credit 4 questions; 30 points total 1. Provide a short description (1-2 sentences) of both evolutionary hypotheses discussed in class, the Red Queen and Constant-Diversity (6 points). 2. There are three different types of viral replication in host cells: cytopathic, noncytopathic and abortive Define each type of replication and what type of disease would you suspect to be typical of each (9 points)

Answer 1

1. The “Red Queen” hypothesis in evolution is related to the coevolution of species. It states that species must continuously adapt and evolve to pass on genes to the next generation and also to keep from going extinct when other species within a symbiotic relationship are evolving.

2. Cells that support viral replication are called permissive. Infections of permissive cells are usually productive because infectious progeny virus is produced. Most productive infections are called cytocidal (cytolytic) because they kill the host cell. Infections of nonpermissive cells yield no infectious progeny virus and are called abortive.

cytopathic, meaning that cells are killed during the course of infection, The changes in cell morphology caused by the infecting virus are called cytopathic effects (CPE). Common examples are rounding of the infected cell, fusion with adjacent cells to form a syncytia (polykaryocytes), and the appearance of nuclear or cytoplasmic inclusion bodies. Inclusion bodies may represent either altered host cell structures or accumulations of viral components.

Some viruses are inherently noncytopathic because their replication programs are relatively benign, while others actively maintain a noncytopathic state by shutting down proapoptotic mechanisms, by activating antiapoptotic mechanics, or by inducing alternative transcription programs that preserve the viral genome without virion production.

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