Lecture 1 Flashcards
Why study viruses?
-Viruses infect all living things
-Viruses are everywhere: outnumbers cellular life 10:1
-We carry viral genomes as part of our own genetic material
-Viruses are important disease-causing agents but not all viruses make you sick
True or false: there are more people on earth than viruses
False: there are more viruses in a liter of costal sea water than there are people on earth
10^31 bacteriophage particles in the ocean
True or false: all viruses are dangerous for us
False: some can be beneficial for us
Viruses catalyse the movement of nutrients from organisms
important players in the regulation of the Earth’s ecology
true or false: viruses can transfer genes between organisms
true
what is the consequence of densovirus on flies
they grow wings
True or false: a virus can’t replace a whole microbiome
false it can in GF mice
What is a virus?
an infecuous, obligate intracellular parasite
what do virus contain?
-genetic material (DNA or RNA)
-Protein coate(capsid)
-In some cases, an envelope (lipid bilayer) derived from host cell membranes
True or false: all viruses go through filters
False: we discovered viruses that are so big like the mimivirus that does not go through the usual filter
usually they are in nm
True or false: we have early recordings of viruses
yes we have dating from egyptians
What are the 3 hypotheses for where viruses come from?
-The virus-first hypothesis
-the regressive or reduction hypothesis
-the progressive or escape hypothesis
What is the virus first hypothesis
Viruses predate or coevolved with their current cellular hosts
What is the regressive hypothesis
Viruses are remnants of cellular organisms (“fourth domain”)
What is the progressive hypothesis?
viruses arose from genetic elements that gained the ability to move between cells
Why are viruses considered as inanimate?
They exist in 2 phases: an inanimate: the virion and a multiplying phases in the infected cell
-viruses are passive: they are completely at the mercy of their environments. They can’t synthesize, exhibit, display, destroy, evade and generate on their own