Inheritance of Genes in Bacteria: 3

Horizontal gene transfer is when __. It was originally thought that __. This assumption was overturned in the 1990s when complete genome sequences were obtained for a variety of bacterial species.

Comparisons of these sequences revealed that the __, suggesting that the barriers to __ are much less rigid than previously thought. It also became clear that although we know a great deal about the processes by which plasmids and chromosomal genes move within species, we know much less about how genes are transferred from one species to another

Plasmids can be transferred between bacteria by __

Bacteria can exchange genes by __; it is __.

The donor cells are referred to as __ and the recipient cells are __

Conjugation involves a __, which__

Explain the fertility factor and formation of the tubelike pilus.

What is the difference between F+ and F-?

Conjugation is always between __. The F+ cell, the one that __, initiates __by __, which __. The two cells become __, and what happens? 

Replication is by the __, with the parent plasmid remaining in the F+ cell and the copy transferring to the recipient F- cell as it is rolled off of the parent.

The F- cell therefore becomes __ 

Theoreticalyl, this should mean that, over time, all E. coli bacterial will become F+. Why is this not the case?

A large number of bacterial species are able to __in the same way as E. coli, and in all of these the process is controlled by a __. Fertility plasmids of this type are called __, which means that they can __ and __

__ and __are two distinct functions, and only self-transmissible plasmids are able to direct both

A few other plasmids can only __ and not __, and some can __

Other plasmids are totally __and can neither __ nor __

Chromosomal genes can also be transferred during __

Bacterial conjugation is important because it does what?

There are several ways, the first being simply that __. This occurs fairly infrequently.

More important are the __ properties of two special types of donor cell, called __.

In Hfr cells, the F plasmid has done what? 

The integrated form of the F plasmid can still do what, but in this case, in a ddition to transferring itself, it also does what?

It takes approximately 100 minutes for the entire E. coli chromosome to be transferred in this way, but conjugation rarely continues for this long. Termination of conjugation interrupts the DNA transfer, so usually only what happens?

F’ cells, the second type of donor cell regularly assoiated with transfer of chromosomal genes, occasionally arise from __ when the __ becomes excised from the genome

Normally this event results in an__, but sometimes __ is not entirely accurate, and a small segment of the adjacent bacterial DNA is also snipped out

This leads to an __ that carries a segment of the bacterium’s genome, possibly including a few genes

Conjugation involving an F’ cell always results in __

Bacterial genes can also be transferred __ between donor and recipient

Bacteria can also acquire segments of chromosomal DNA from other cells by processes that do not involve __ via __ and __

Transformation: __

Some bacteria have efficient mechanisms for __ 

The outer membranes of these species contain __

Other species, including E. coli, do not have __, but some DNA can still penetrate the outer surface of the bacterium and enter the cell

Transduction: __

Some bacteriophages do not immediately __. Instead, the virus genome becomes __, just like an F plasmid in an Hfr cell

The integrated virus genome is called a __

At some stage the prophage will __

 This is accompanied by __, some of which, by chance, will be about the same size as the bacteriophage genome

By mistake, one of these small chromosome fragments might be __. The resulting particle is still __, as infection is solely a function of the proteins within which the DNA is enclosed. The fragment of bacterial DNA can therefore be transferred to a new cell when that recipient becomes “infected” with the __

Transferred bacterial DNA can become a permanent feature of the recipient’s genome If the DNA that is acquired by __, __, or __,  it will be able to __, adding to the __ This is the outcome of most __events and might also arise from __, as it is quite possible for plasmid DNA to be taken up from the environment in this way

__ is immensely important in microbiology because it is responsible for the __ 

This brought about the evolution of __

Chromosomal DNA that is acquired might be __ for the __

 Sometimes DNA can __. For this to happen, the DNA must __

This is possible if the transferred DNA has the __, as will be the case if it comes from the same species.

The segment of transferred DNA might then __

If this happens then the recipient bacterium will __. As the genes are the same as the ones that it had before, the replacement might appear to be immaterial.

But, bacterial genes, just like eukaryotic genes, have variant forms called __, each one that it had before, the replacement might appear to be immaterial

But bacterial genes, just like eukaryotic genes, have variant forms called __, each one with a slightly different DNA sequence Transfer might therefore result in the __. Its biological characteristics might therefore change in a small way

Genome sequencing projects have told us that __.

Suggested mechanism: __

The incoming DNA is unlikely to have __ with any part of the recipient’s chromosome, so __is assumed to occur __

Once it becomes a part of the chromosome, the new DNA, and any genes it contains, will __

__ might not happen very frequently, but it occurs often enough for bacteria to acquire, from time to time, new genes from other species