Chapter 18 Bio 121

Bacterial gene transfer can occur in three ways:

1. Conjugation 2. Transformation 3. Transduction

How do bacteria cells divide

not by mitosis, but instead by a process called "binary fission"

Host range

the infection target of viruses. The host range denotes what species the virus can inject, and what type of cell it is capable of infecting. Thus, some viruses can only infect certain types of bacteria (These are called bacteriophages or just phages). Other viruses have more specific targets. HIV for example, has a host range of primates (species) and T-cells (cell type).

Transduction

When viral particles are assembled, sometimes they incorporate pieces of host cell DNA. These pieces can be transferred to a newly infected bacterial cell, and integrate into its genome

Transformation

does not involve direct cell contact. when a cell dies, pieces of DNA fragments in the outside environment can be taken up by bacterial cells (through a protein channel) and these pieces of DNA can integrate into the host cell genome.

Bacterial plasmids

Extrachromosomal circular pieces of DNA. Have their own ORI, so they can be replicated. They are naturally occurring. Unlike bacterial chromosomes, bacterial plasmids can be transferred from one bacteria to another (by conjugation)

Prions

Prions are infectious particles only made up of protein.

The reproductive cycle of viruses is composed of ...

A.) Attachment B.) Entry (entry of genetic material) C.) Integration * (sometimes skips this step, it this step is included, the virus enters the lysogenic stage/latency period: i.e., the stage where the viral genes are not expressed, and thus the virus is dormant) D.) Synthesis of viral components E.) Assembly of the virus F.) Release: Note: D-F represents the lytic cycle, where the cell membrane can burst open, and viruses are released and can go on to infect new cells.

Viroids

infections particles only made up of RNA.

Viruses

infectious, non-living particles simple made out of genetic material (some have DNA or some Have RNA), and a protein shell (called a capsid). some viruses also have a membrane/envelope/phospholipid bilayer that surrounds it.

Conjugation

involves direct cell contact, a sex pillus to form a cytoplasmic connection, with the ultimate goal of replicating and transferring plasmids.