Microbio Unit 5 (Viruses)

Viral genomes are protected by...

• Polysaccharide network

• Protein coat known as a capsid

• Double membrane

• Cytoskeleton proteins forming a ring

Some viruses have a phospholipid membrane. This is derived from...

• The extracellular environment

• Host nuclear membrane

• Translation of viral genes

• Host plasma membrane

Which is NOT a possible capsid morphology (shape)?

• tetrahedral

• helical

• icosahedral

• complex

Viruses can have the following genetic material, EXCEPT...

• double-stranded RNA

• single-stranded RNA

• triple-stranded DNA

• single-stranded DNA

Viral life cycles...

• Involve a specific host

• Prefer certain tissue or cell types (tropism)

• Can be lytic or lysogenic

• All of the above

Inhibition of the interaction between HIV gp120 and host T cell CD4 would...

• Prevent viral attachment to T helper cells

• Allow attachment, but prevent replication

• Allow replication, but prevent budding

• Allow budding, but virions would be noninfectious

HIV reverse transcriptase...

• Copies genomic RNA to DNA

• Makes few mistakes during replication

• Degrades DNA after replication

• Has protease activity

What is TRUE about retroviral genes?

• env codes for matrix & capsid proteins

• gag codes for reverse transcriptase

• env is cleaved by viral protease into gp160

• pol codes for a polyprotein, processed by viral protease

Phage replication is indicated by...

• Turbidity (opaqueness) on a bacterial lawn

• Clearings (plaques) on a bacterial lawn

• Inability to pass through a membrane filter

• Growth on mammalian cells

Getting rid of phage lambda protein "cII" would cause...

• Entry into the lytic cycle rather than lysogenic cycle

• Integration of the phage into the bacterial genome

• Prevention of viral DNA injection

• Blockade of theta replication