chapter 25 section 1 Flashcards
what is a virus ?
a nonliving particle composed of a nucleic acid and a protein or lipoprotein coat
what is a capsid?
the protein coat that surrounds the nucleic acid in a virus
what is a retrovirus?
a virus that contains RNA and the enzyme reverse transcriptase
what is a viroid?
smallest known particles that are able to replicate.
consists of a short, single strand of RNA and has no capsid
what is a prion?
abnormal forms of protein that clump together inside a cell
the diameter of viruses range from about
20-250 nm (nanometers)
viruses can reproduce
only within host cells
the enzyme reverse transcriptase uses
RNA as a template to make DNA
the grouping of viruses is based partly on the
presence or absence of an envelope
a disease causing particle made of RNA without a capsid is called
a viroid
what did wendel stanley do
crystallize the tobacco mosaic virus
what did wendel stanleys work suggest about the nature of viruses
that viruses were chemicals rather than tiny cells
2 strucutres of cells but not viruses
nucleus
cytoplasm
2 activities of cells but not viruses
cells can reproduce without help
cells are living organisms
what is the function of the glycoprotein on the surface of enveloped viruses
the viruses use glycoprotein to attach to the surface of a host cell
