Intro Deck

Question 1

What is a virus?

Answer 1

An obligate intracellular parasite that can only replicate in living cells

Question 2

What is a virion?

Answer 2

The extracellular form of a virus

Question 3

What are the 2 or 3 things a virus is composed of

Answer 3

1. genome
2. capsid (protein coat around the capsid… when found with the genome it is called the nucleocapsid)
3. sometimes an envelope

Question 4

What are the 3 variations of genome

Answer 4

1. RNA or DNA
2. single strand or double strand
3. • strand or - strand

What is a positive and negative strand? positive strand is same sense as viral mRNA and negative is complementary to the viral mRNA

Question 5

What are the 5 criteria for classifying a virus

Answer 5

1. type of genome
2. symmetry of capsule: helical, icosahedral, complex
3. envelope (yes or no)
4. mode of replication
5. tropism or pathology

Question 6

What are the 8 steps of virus replication

Answer 6

1. binding to surface receptor
2. penetration through the plasma membrane
3. uncoating
4. synthesis of viral mRNA (transcription)
5. synthesis of viral proteins
6. amplification of viral genome (replication)
7. assembly of progeny virions
8. egress from infected cell

Question 7

What are the 3 pathways that a virus enters a cell

Answer 7

1. fusion of the envelope with the surface plasma membrane
2. receptor-mediated endocytosis followed by fusion with the endosome membrane
3. lysis of the endosome

A host cell can be permissive or non-permissive which will lead to a productive or non-productive infection