PCB 3064 Chp 7

cotransduction frequency

(1-d/L)^3 d= distance between two genes in muntues L= size of chromosommal pieces (in minutes) that the phage carrys during transduction P1 2 minutes P22 1 minutes or less

F factor

(Fertility Factor)made by F+ strains. needed to donate genetic material between bacterium A type of DNA that exist independently from chromosomal DNA (Plasmid)

HFR Strains

(High Frequency of Recombination) Strains of E. coli Luca Sforza discorvered HFR can transfer chromosomal genes to F factor strains

What is required in order for genetic material to be transferred between two bacterial cells by conjugation?

Physical connection between two cells

cotransduction mapping

A technique that uses cotransduction frequencies to determine the relative order of multiple genes that are within 2.5 minutes. The frequency of cotransduction is greater for genes that are closer together because they are more likely to be on the same fragment of DNA.

Plasmid

A type of DNA that exist independently from chromosomal DNA; Usually circular DNA

Bacteria may contain different types of

Plasmids

HFR integrate with bacterial chromosomes? Genetic Variation

HFR usually integrate next to the lac+ gene in a chromosome. They recombine and take some of the bacterial chromosome with them as they leave and transfer into another bacterium. Lac+ is transferred first linearly then pro+ later. ( depends where the f factor connects to the DNA)

A bacterium is typically (Blank) for a particular gene, meaning that it only has one copy of the gene.

Haploid

What event is required for genes on an Hfr chromosome to be transferred onto the recipient cell's chromosome?

Homologous recombination because While replication occurs to restore double-stranded DNA structure, recombination is required to integrate genes into the chromosome of the recipient cell.

cotransduction

Process in which two or more genes are transferred together from one bacterial cell to another. Only genes located close together on a bacterial chromosome will be cotransduced.

Conjugation was first observed by

Joshua Lederberg and Edward Tatum in 1946

The incorporation of a transformed DNA fragment into the bacterial chromosome at a random site is called (blank) recombination.

NonHomologous

Genetic Transfer

On which a segment of DNA is transferred from one bacterium to another through three mechanisms: Conugation, Transduction, and Transformation

lytic cycle and lysogenic cycle

Phages have two alternative reproductive mechanisms:

Virulence Plasmids

carry genes that turn bacterium into pathogenic strains

competent cells

cells that are capable of accepting genetic material through transformation; accepts foreign dna

During transformation, homologous recombination may create a region of DNA containing one or more base mismatches that must be repaired. This region is called the ______.

heteroduplex

In order to be replicated independently of the bacterial chromosome, a plasmid must have its own

origin of replication

Transduction process

phages can mutate to take fragments of the hosts DNA to enter other cells. Causing more recombination thus genetic Variation (from (his-) to now being able to absorb histone (his+)

Episomes

plasmids that can integrate into a chromosome

Relaxosomes

protein complex encoded by the F-factor. makes a cut at the origin of transfer and begins to separate the DNA strands

Nucleoproteins

proteins (relaxase) associated structurally with nucleic acids (DNA)

Bacteria

reproduce asexually. Is usually a haploid with regards to certain gene

The competence-stimulating peptide of Streptococcus pneumoniae ______.

stimulates nearby cells to express competence proteins

Transduction

When a virus infects a bacterium and then transfers bacterial genetic material from that bacterial to another

How long does it take for an entire Hfr chromosome to be transferred from an Hfr strain to an F- cell?

1.5 to 2 hours

Prototroph

A bacterium that does not require an added nutrient to their minimal medium

Auxotroph

A bacterium that lacks the ability to syntheisze a molecule it needs to live and needs substance added to their medium

Conjugation

A direct physicla interaction between two two bacterial cells. Onne Donates material to another cell

genetic map unit

A distance on the chromosome map in minutes from the time it takes to enter the f- cell

What is a heteroduplex?

A region of DNA containing one or more mismatches that must be repaired

Base Pairs

BP

Bacteria that can take up DNA from the environment carry genes encoding proteins that aid DNA binding to the cell surface, uptake of DNA into the cytoplasm, and incorporation of foreign DNA into the bacterial chromosome. These proteins are called (Blank) factors.

Competent

Resistance plasmids (R factors)

Contain genes that confer resistance against antibiotics and other types of toxins

Advangtage of GEnetic Transfer

Enhance gentic diversity

Transformation

Gentic material is released into the environment whena bacterial cell dies. Then living bacteria takes the material

horizontal gene transfer (HGT)

The transfer of genetic material to an organism that is not the offspring of the donor organism is referred to as

What is the significance of a plasmid's origin of replication?

It allows the plasmid to be copied separately from the bacterial chromosome.

acquired antibiotic resistance

The common phenomenon of a previously susceptible strain of bacteria becoming resistant to a specific antibiotic.

During conjugation, the starting point and direction of DNA transfer are determined by a DNA sequence within the F factor called the ______.

The origin of transfer

Acquired antibiotic resistance

The phenomenon in which a bacterial strain that is susceptible to a specific antibiotic becomes resistant to that antibiotic is called

Frederick Griffith is known for the discovery of ______.

Transformaation

Which form of genetic transfer involves competence factors?

Transformation

Which of the following statements about transformation is correct? Multiple choice question. Transformation is a natural process that has evolved in some species of bacteria. Transformation occurs only in bacteria that have been genetically engineered. Transformation is a natural process that occurs in some types of eukaryotic cells, but not in bacteri

Transformation is a natural process that has evolved in some species of bacteria.

U-tube

With pressure and suction allows the movemeny of liquid. has a filter in the middle to filter everything but dna. on either side of the U two strands of bacteriawere addeed. proved that without physical contact of both strains, genetic material could not be transferred.

lytic cycle

a viral reproductive cycle in which copies of the DNA are made within a host cell, and make new phages that are then released. But can also mutate to take fragments of the hosts DNA to enter other cells. Causing more recombination thus genetic Varitioin

Sex pili

acts as a attachment rsite that helps bind two bacteriums together

The functions of competence factors include ______.

aiding the uptake of DNA into the cytoplasm of a bacterial cell incorporating DNA into the bacterial chromosome allowing DNA fragments to bind to the surface of a bacterial cell

The functions of competence factors include ______.

allowing DNA fragments to bind to the surface of a bacterial cell aiding the uptake of DNA into the cytoplasm of a bacterial cell incorporating DNA into the bacterial chromosome

F' Factors

an F factor that also carries genes derived from the bacterial chromosome

Horizontal Gene Transfer

an organism incorporates genetic material from another organism without being the offspring of that organism

A Streptococcus pneumoniae cell may begin to express competence proteins if a nearby cell secretes the _____ peptide.

competence- stimulating peptide

During conjugation, the chromosome in the Hfr strain is first (blank) , then transferred into the F— cell, where it may (blank) with the homologous region of the recipient cell's chromosome.

cut; recombine

Degraditive Plasmid

enable bacteria to digest and utilize unusual substances

Col plasmids

encode colicines which are proteins that kill other bacteria

Purpose of bacterial gene mapping

illustrate the mechanism used to transfer Genetic material and helps to understand new mapping strategies.

Wollman and Jacob used a blender to separate bacterial cells in the act of conjugation without killing the cells. Their technique is called (blank) mating.

interrupted

Environmental factors that can influence whether or not a bacterial cell is competent include ______.

ionic conditions temperature nutrient availability

In a conjugation experiment between between the two cells shown here, transfer of both the leu+ and thr+ genes could be monitored by growing the recipient cells on media ______. lacking leucine, but containing threonine containing both leucine and threonine containing leucine, but lacking threonine lacking both leucine and threonine

lacking both leucine and threonine Because the recipient cells lacked genes to make leucine and threonine, they would have to be grown on media that lacked these amino acids to demonstrate the gene transfer occurred.

Conjugation Expirements can Map genes along the E. coli Chromosomes

they analzye by observing the genes that are gained after specific times during conjugations. THey used blender to seperate the strains after letting them conjugate for a certain amount to figure out what genes were closer to the origin of transfer. then put them in a growth medium and analyzed their rate to kill azr genes.

bacteriophages (phages)

viruses that infect bacterial cells