Gene Transfer

Vertical Gene Transfer

Occurs when an organism replicates its genome and passes it on to its own progeny (child). Cell replicates its genome and reproduces by cell division and the daughter cell receive a copy of the genome from the parent cell

Horizontal Gene Transfer

When genetic material such as part of the genome or a plasmid is transferred between individuals of unrelated generations, can occur between the same or different species

Conjugation

Transferring copies of plasmids through a sex pilus, mediated by sex fertility or F factor

Horizontal gene transfer

Transformation

A bacteria dies, releasing its DNA into the environment, another bacteria picks up this DNA

Horizontal Gene Transfer

Transduction

DNA is mistakenly transferred from one bacteria to another by a bacteriophage (virus) when the protein coat takes up bacteria DNA instead of the viral DNA

Horizontal Gene Transfer

Fertility or F Plasmid

The location for the gene coding for the sex pili in conjugation

F+ Cell

Bacteria cells with F plasmid in conjugation, called the donor since they will donate a copy of the F plasmid

F- Cell

Bacteria without the F plasmid, called the recipient since they will receive a copy of the F plasmid

Frederick Griffith

First to discover bacteria transformation in 1928, discovered that DNA could be passed from dead cells to live cells

Streptococcus Pneumoniae Smooth Strain

Pathogenic and deadly, smooth colony appearance is cause by the bacteria having a capsule, allowing it to evade the mouse’s immune system

Streptococcus Pneumoniae Rough Strain

Non pathogenic or harmless to mice, this strain does not have a capsule

Mouse Death

Griffith Experiment, Mouse infected with smooth strain bacteria

Mouse Survival

Griffith Experiment, mouse infected with rough strain bacteria

Mouse Survival

Griffith Experiment, mouse infected with smooth strain bacteria destroyed by heat

Mouse Death

Griffith Experiment, Mouse infected with a mixture of rough strain and smooth strain bacteria destroyed by heat

By making a capsule from the smooth strain

How did the mouse die with a mixture of rough strain and smooth strain bacteria destroyed by heat?

Step One of Transduction

The phage attaches to the surface of the bacteria

Step Two of Transduction

The viral DNA enters the host cell

Step Three of Transduction

Bacteriophage DNA replicates and phage proteins are made

Step Four of Transduction

New phage particles are assembled

Step Five of Transduction

The cell lyses, releasing the newly made phages