Chapter 6: Viruses Flashcards
Viruses characteristics
- considered particles
- are not alive
- ultra microscopic
- DNA/RNA allows them to reproduce
what does the term virus mean in Latin?
poison
who coined the word for virus
L. Pasteur
what do viruses have in common with cells?
the presence of nucleic acids
what type of microscope is necessary to observe viruses?
electron microscope
- they are measured in nanometers
what is a capsid
- a layer of protein acting as a shell surrounding the virus’ genetic material
what is an intracellular parasite
can only reproduce inside the cell
What is the largest virus?
poxviruses; size of small bacteria
How many genes does the Hepatitis B virus have?
4
what is the smallest virus?
parvovirus
what is Reverse Transcriptase and what is an example of a virus with such feature?
an enzyme present in some RNA viruses that allows the mRNA to be converted back to DNA
ex. Retrovirus
- this does not happen in regular biology
when is a virus considered a naked virus?
it only consists of a capsid
when is a virus classified as an enveloped virus?
virus has extra layer of phospholipids (envelope) in addition to the capsid
what are spikes and their function?
aka peplomers
- made of a glycoprotein
- function is to recognize a receptor to bind to a cell to reproduce
- acts as a key finding a lock
examples of complex viruses
- bacteriophages: viruses that affect bacteria
- T4 virus (looks like a spacecraft)
- poxviruses
what are the different type of viral morphology?
- naked
- enveloped
- complex
what is the genome?
sum of all genetic information carried by an organism or virus
describe the genome of a virus
consists of only the necessary enzymes to cause infection
ex. T4 has a special enzyme that, when attached, opens a hole in a cell to inject its DNA into the host cell
what kind of genetic material does a virus have?
DNA or RNA, but not both
- single stranded DNA
- double stranded DNA
- double stranded RNA
- single stranded RNA
examples of single stranded DNA viruses
- parvovirus: kills puppies
- geminivirus: in agriculture
what is meant by linear non fragmented
genome is organized in a continuous sequence, round or linear when stretched
what is meant as linear fragmented
ex. flu virus has 8 pieces of RNA
ex. reovirus has 11 pieces of RNA
example of double stranded RNA
- reoviridae
»>rotavirus: causes diarrhea in children
which DNA virus has both double and single stranded portions of DNA?
Hepatitis B
- considered a defective virus