Chapter 18 Flashcards
what is a virus?
an infectious particle made only of a strand of DNA or RNA surrounded by a protein coat
describe the structure of a virus?
nucleic acid core and protein coat
why do viruses not have scientific names?
they are unliving
what is a disease causing agent called?
pathogen
what are four key characteristics that all living things share?
abilities to reproduce, use nutrients and energy, grow and develop, and respond to environments
what are viroids?
infectious particles that cause disease in PLANTS
what are viroids made of?
single stranded RNA and a protein coat
how are viroids transported?
through seeds and pollen
what is a prion?
an infectious particle made only of proteins that can cause other proteins to fold incorrectly
what happens when proteins are folded incorrectly?
they do not function properly
what is unusual about prions?
they are infectious yet contain no genetic material
what disease do prions play a part in?
mad cow disease/bse
what is the unifying characteristic of protists, fungi, plants, and animals that are all in the domain archaea?
they all have a nucleus
how do humans get bse?
eating meat from animals infected from the disease
name the domain each kingdom is in?
bacteria-bacteria
fungi protest animal- eukarea
archae- archae
diseases brought on by prions are always what?
fatal
why are these prion diseases always deadly?
the body has no immune response against a protein
what is the common factor between viruses, bacteria, viroids, and prions?
they can all cause infection
true or false: viruses are all the same shape and enter host cells the same way
false: viruses differ in shape and in ways of entering host cells
what is a virion?
a single, viral particle made up of genetic material surrounded by a capsid
what is a capsid?
the protein shell that surrounds virions; sometimes surrounded by a lipid envelope that is a protective outer coat of virus, from which spiky structures of proteins and sugars stick out
when and only when can viruses reproduce?
after they have attached to a host cell
what is an obvious trait of some viruses that can be used for identification?
spikes
how does a virus attach to a host cell?
virus identifies its host by fitting its surface proteins to receptor molecules on the surface of a host cell, like a key fitting a lock
