Bacterial Viruses

Lecture Outline:

1. Hallmarks that distinguish a living from a nonliving system (self-feeding, self-replication, differentiation, chemical signaling, and evolution). Why are virus not considered living by some people?

2. Properties of viruses:

3. General step in replication of a virus:

4. Examples of how certain phage replicate:

5. Lysogeny: Phage l (lambda). Fig. 13.6

6. Lysogenic conversion (new cell properties acquired as a consequence of carrying or harboring a prophage)- examples See Table 13.3

7. Mechanisms to resist phage infection- lack or modify phage receptor and/or make a restriction endonucleases that recognizes specific DNA sequences of phage genome. Restriction endonucleases, have ability to recognize specific nucleotide sequences within a DNA molecule, and cut the DNA. Cells protects own DNA by modifying a nucleotide within sequence recognized by a specific restriction endonuclease. In general, only one restriction endonuclease and modifying enzyme per species.

Learning Objectives:

Examples of lysogenic conversion: