Chapter 26 Review

Virus

Infectious particle of genetic material in a protein coat; cannot replicate outside a host.

Capsid

Protein shell that encloses viral genome, made of capsomeres.

Capsomere

Protein subunit that builds the capsid.

Helical Virus

Rod-shaped virus with helical capsid arrangement.

Icosahedral Virus

Virus with 20-sided polyhedral capsid.

Viral Envelope

Membrane around some viruses; derived from host and contains viral glycoproteins.

Host Range

Set of host species a virus can infect.

Lytic Cycle

Viral replication cycle ending in host cell lysis and death.

Virulent Phage

Phage that only replicates via the lytic cycle.

Lysogenic Cycle

Phage genome integrates into host DNA and replicates without killing host.

Prophage

Phage DNA integrated into bacterial chromosome.

Temperate Phage

Phage that switches between lytic and lysogenic cycles.

Restriction Enzymes

Bacterial enzymes that cut foreign DNA.

CRISPR-Cas System

Adaptive bacterial defense that cuts viral DNA using stored viral sequences.

Retrovirus

RNA virus that uses reverse transcriptase to make DNA.

Reverse Transcriptase

Enzyme that transcribes viral RNA into DNA.

Provirus

Integrated viral DNA that is a permanent part of host genome.

Positive-sense RNA

Viral RNA that can be directly translated as mRNA.

Negative-sense RNA

Viral RNA that must be converted to positive-sense RNA.

Vaccine

Harmless derivative of a pathogen that stimulates immunity.

Prion

Infectious misfolded protein causing neurodegenerative disease.