Figure 10.22. VIRUSES: GENES IN PACKAGES. Viruses Components Infection cycle 3. DNA, RNA viruses 4. Uses of viruses. Components of a virus (phage). 1. Protein coat = capsid 2.genetic material DNA or RNA 3. enzyme. Components of a virus. Membranous envelope. envelope capsid
3. DNA, RNA viruses
4. Uses of viruses
1. Protein coat = capsid
DNA or RNA
Phage DNA directs host cell to make more phage DNA and protein parts. New phages assemble.
Phage attaches to bacterial cell.
Phage injects DNA.
Cell lyses and releases new phages.
Cell lyses,releasing phages
Phage injects DNA
Occasionally a prophagemay leave the bacterialchromosome
Lysogenic bacteriumreproduces normally,replicating the prophageat each cell division
New phage DNA andproteins are synthesized
Phage DNA inserts into the bacterialchromosome by recombination
RNA synthesisby viral enzyme
RNA synthesis(other strand)
Figure 10.20A, B
Makes use of viral ability to enter only cells of one type
Allows targeting of therapy to tumor cells
Enables identification of small tumor sites