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.