Micro: Genetic Recombination

Transduction

- Bacteriophage serves as a carrier of DNA from a donor cell to a recipient cell - Two types: Generalized and Specialized - One way of how we get genetic diversity

Transformation

- Chromosome fragments from a lysed cell are accepted by a recipient cell; The genetic code of the DNA fragment is acquired by the recipient - Donor and recipient cells can be unrelated

3 Means of Genetic Recombination in Bacteria

- Conjugation - Transformation - Transduction

Transposons

- Special DNA segments that have the capability of moving from one location in the genome to another; "jumping genes" - Cause rearrangement of genetic material - Can move from one chromosome site to another, from a chromosome to a plasmid, or from a plasmid to a chromosome - May be harmful or beneficial

F' (Prime) Conjugation

- When an HFr cell deintegrates, it can revert to an F+ cell - When an HFr cell deintegrates improperly, it may leave a piece of the plasmid behind or take some of the host cell's chromosome with it - This will change the genome

F' and F- Conjugation

2 F'

F+ and F- Conjugation

2 F+

HFr and F- Conjugation

2 HFr F-pillus is what holds them together

Mutation

A change in phenotype due to a change in genotype (nitrogen base sequence of DNA); Increases diversity and their ability to survive

Specialized Transduction

A highly specific part of the host genome is regularly incorporated into the virus; During the lysogenic cycle (temperate)

Indicator Organism in the Ames Test

A mutant strain of Salmonella typhimurium that has lost the ability to synthesize histidine. This mutation is highly susceptible to back-mutation

Wild-Type

A natural, nonmutated characteristic; Wild strain

What is the difference between the F+ cell and HFr cell?

An F+ cell has the plasmid outside the chromosome. An HFr cell has the plasmid incorporated (episome)

Mutant Strain

An organism that has a mutation showing variance in morphology, nutritional characteristics, genetic control mechanisms, resistance to chemicals, etc

The Ames Test

Any chemical capable of mutating bacterial DNA can similarly mutate mammalian DNA. Agricultural, industrial, and medicinal compounds are screened using this test.

In order for it to uptake the genetic material, it must be ____?

Competent

F- Cell

Doesn't have the f-plasmid

When is a competent factor produced?

During the log (exponential) growth phase; Therefore, expect transformation to occur during the log (exponential) growth phase

F+ Cell

Has the f-plasmid

F-plasmid

Has the genes that code for the creation of the f-pillus

HFr Cell

High frequency of recombination; Like an episome; When it leave, it can take a piece of the bacteria; Cell is more likely to undergo conjugation; When conjugation occurs, a portion of the chromosome and a portion of the fertility plasmid are transferred to the recipient

What does the Ames test tell us?

If something is found to be mutagenic, it is possible to also be carcinogenic. The way they know is by looking at things known to be carcinogenic. OR Something that is possibly carcinogenic might be detected by its ability to cause a mutation

Transcription

Information stored on the DNA molecule is conveyed to RNA molecules through this process

Reverse Mutation

Mutation back to original form

Genetic Recombination

Occurs when an organism acquires and expresses genes that originated in another organism

Spontaneous Mutations

Random change in the DNA due to errors in replication that occur without known cause

Generalized Transduction

Random fragments of disintegrating host DNA are picked up by the phage during assembly; Any gene can be transmitted this way; During the lytic cycle (virulent)

Induced Mutations

Result from exposure, to known mutagen, physical (primarily radiation) or chemical agents that interact with DNA in a disruptive manner

What is the difference between a rough and smooth colony?

Rough colonies have no capsule while smooth colones have a capsule.

Mutagen

Something that causes a mutation

Behind the Ames Test

Take something that is already a mutagen (Salmonella that does not produce histidine). Expose it to a potential mutagen and find whether is reverts back to a wild type. A normal wild type Salmonella does produce histidine in the media. A mutagen does need histidine added to the media to grow since it does not have histidine.

Translation

The information contained in the RNA molecule is then used to produce proteins in this process

What is the purpose of the Ames Test?

To help identify whether or not a particular compound is mutagenic or carcinogenic

Horizontal Gene Transfer

Transfer of genetic material from one mature bacterium to another

Hypermutation

Under mutation more frequently and at the end of this, can survive in an environment that they would have not been able to survive

How does an F-pillus form?

When there is an interaction with another organism

Fertility, Conjugative, or F-Plasmids

Which are capable of conjugation and result in the expression of sex pili

Resistance Plasmids

Which contain genes that provide resistance against antibiotics or poisons. They are historically known as R-factors, before the nature of plasmids was understood

Col Plasmids

Which contains genes that code for bacteriocins, proteins that can kill other bacteria.

Degradative or Metabolic Plasmids

Which enable the digestion of unusual substances

Virulence Plasmids

Which turn the bacteria into a pathogen