Chapter 22 - The Viruses

Question 1

What do Viruses lack?

Answer 1

Ribosomes - therefore they cannot be classified w/in 3 domains

Question 2

baltimore scheme

Answer 2

viral classification scheme - focuses on relationship between a viral genome and how it produces mRNA.

Question 3

Class I: dsDNA

Answer 3

Have genome the exact same as the host cell they are infecting - therefore host enzymes can be used for replication and protein production

Question 4

Class I: dsDNA pathway

Answer 4

dsDNA -> mRNA -> Protein

DNA-dependent RNA-polymerase produces mRNA, host ribosome produces protein

Question 5

Class I: dsDNA genome replication

Answer 5

requires DNA-dependent DNA-polymerase from either host or virus

Question 6

Class I: dsDNA - T4 - how is gene expression controlled?

Answer 6

Host RNA polymerase binds to viral DNA, begins transcribing early genes right after DNA is injected into the cell. An early protein then modifies host RNA polymerase so it no longer recognize host promoters, moves to transcribe middle-stage proteins. Then RNA polymerase will code for late stage proteins.

Question 7

concatemers

Answer 7

several viral genomes are linked together due to short single-stranded regions with terminal repeats - because of several dsDNA replications

Question 8

Productive Infection

Answer 8

Results in an explosive viral population, cell death, and development of disease signs, during which neurons are infected.

Question 9

Latent infection

Answer 9

Develops in the neurons, allowing the virus to remain undetected in the host.