Microbio Exam 3
What are the steps of bacterial transformation?
1. bacteria encounters foreign DNA from the environment 2. DNA binds to the DNA-binding proteins (receptors) 3. Nuclease dissociates the DNA into single strands 4. a single stranded fragment of DNA is imported into the cell 5. This fragment is protected by nucleases by competence specific single strand DNA binding proteins 5. RecA protein delivers the single stranded DNA into the host-chromosome via RecA-mediated homologous recombination 6. foreign DNA is duplicated with bacterial DNA after the next round of cell division
How long does Hfr conjugation take?
100 minutes
The Calvin cycle pathway requires _________total atp input and ____ total NADPH input
9 atp and 6 NADPH
What is a plasmid DNA cloning vector?
A plasmid DNA cloning vector is a small, circular piece of DNA that is used to carry and replicate foreign DNA in a host organism, usually bacteria. Cloning vectors are commonly used in molecular biology research to create recombinant DNA molecules, which are formed by combining DNA from different sources.
What is a F' plasmid
A plasmid that contains some of the original chromosomal DNA along with the F factor genes.
Describe F' conjugation
A process that occurs when the F factor leaves the host chromosome incorrectly to create the F' plasmid and becomes an episome leaving some of the F factor genes behind in the bacterial chromosome. However the F' plasmid episome brings some chromosomal genes with it (ones that were nearby the F factor) The F' plasmid can be transferred to a recipient bacteria by F' conjugation
What type of metabolism do fungi have
Absorptive metabolism which involves secreting enzymes that break down complex organic molecules in their environment into smaller, more easily absorbed molecules that can be taken up by the fungal cells.
After the sex pilus establishes contact between F+ and F- cells what does it do next?
After contact is made, pilus retracts, bringing cells into close contact and the F+ cell assembles a type of IV secretion apparatus. Think of the Type IV secretion apparatus like a bridge that connects the F+ and F- cells. The F factor plasmid technically moves through the type IV secretion bridge
What does RecA protein do in transformation ?
After extracellular DNA is taken up by a bacterial cell, the RecA protein binds to the single-stranded DNA (ssDNA) and mediates its pairing with homologous sequences in the host genome.
What organisms are protists?
Algae, Protozoa, and slime molds
The Chromalveolata supergroup is a large diverse group of eukaryotic organisms that include two subgroups which are ?
Alveolata and Stramenopila
What did the U tube experiment reveal regarding conjugation?
An experiment designed to investigate the mechanism of genetic exchange between bacterial cells Two strains of Salmonella typhimurium, each with different nutritional mutations, were cultured in each arm of the U-tube A filter was used to block direct bacterial contact between the two strains Prototrophic colonies of Salmonella typhimurium were produced at a high efficiency, indicating that genetic exchange had taken place Further experiments revealed that a small bacteriophage, phage P22, was able to pass through the filter and infect the bacterial cells The P22 bacteriophage carried a prophage, a segment of chromosomal DNA from the parental bacterial cells, which could integrate into the recipient bacterial chromosome This experiment demonstrated that physical proximity between bacterial cells was not necessary for genetic exchange to occur and paved the way for further research into the mechanisms of horizontal gene transfer in bacteria.
Approximately how many cells of E.coli spontaneously revert from auxotrophic form to prototrophic form? What is the problem that can arise from this conversion?
Approximately 1 in 10^6 cells revert If a single auxotrophic marker is used to select for a specific genetic trait, the presence of spontaneous reverse-mutation events can confound the analysis.
Describe Dictyostelium Discoideum
Are slime molds Model organism for research Feeds on bacteria and yeast Apart of the Amoebozoa supergroup Exhibits both unicellular and multicellular behavior The change from Unicellular to multicellular is triggered on nutrient limitation
What are the two modes of spore formation for reproduction for fungi?
Asexual (vegetative) Sexual
Lichens fungi
Associations with algae or Cyanobacteria
What bacteria became more tractable for transformation research then streptococcus pneumonia?
Bacillus (was easier to manipulate and more efficient)
What did Antony Van Leeuwenhoek discover?
Bacteria Sperm cells Blood cells Protists
What are bacterial plasmids?
Bacterial plasmids are small, circular, double-stranded DNA molecules that can exist independently of the host chromosome or integrate reversibly into the host chromosome as episomes. Some genes apart of plasmids may include antibiotic resistance, virulence factors, metabolic enzymes, etc.
Who earned Nobel prize for one gene/one enzyme
Beadle and Tatum
Which experiment proved that direct cell contact was necessary for conjugation to occur?
Bernard Davis U-tube Experiment Used auxotrophs
Mycelium (plural mycelia)
Bundles or tangled masses of hyphae
What type of heterotrophic organism are fungi?
Chemoorganoheterotrophs which means that they obtain their carbon and energy from organic molecules that they absorb from their environment.
The Archaeplastida supergroup is a diverse group of eukaryotic organisms that includes the sub group _____________
Chloroplastida
How are cilia structured?
Cilia are made up of a series of microtubules arranged in a "9+2" pattern consisting of nine outer tubules and two inner tubules.
What is the property of conjugative plasmids?
Conjugative plasmids such as the F plasmid can transfer copies of themselves to other bacteria during conjugation
What are two classes part of the Eumycotozoa group
Consists of Myxogastria and Dictyostelia
What are the benefits of fungi
Decomposes Industrial fermentations (fermented foods and beverages) Steroids, antibiotics and other drugs Model eukaryotic organism for research
Avery, MacLeod, McCarty experiment outcome?
Determined that DNA was Griffith's "Transforming Factor."
The alveolata subgroup consists of three major groups of organisms which are
Dinoflagellates (Dinoflagellates) Ciliates (Ciliates) Apicoplexans (Apicoplexans)
In Hfr conjugation, the direction of transfer depends on what?
Direction of transfer depends on the orientation of the F factor.
Are donor genes (chromosomal genes) transferred during F+ x F- mating to the recipient cell?
Donor genes are usually not transferred along with the F plasmid. (Rare instances do occur)
What are dynein arms?
Dynein arms are molecular motors that are attached to the outer tubules of the cilia. They are responsible for generating the force that drives the movement of the cilia. Dynein arms use energy from ATP hydrolysis to move along the microtubules, causing the cilia to bend and generate movement.
How do yeasts reproduce?
Either asexually by budding Or Sexually by formation of spores
What is the favored type of method for transforming E.coli
Electroporation Involves the application of an electric field to create pores in the cell membrane
When the F factor that is chromosomaly located in the Hfr chromosome leaves the chromosome it becomes an ________
Episome
Are protists and fungi eukaryotic or prokaryotic?
Eukaryotic
Fungi secrete what type of enzymes to digest insoluble matter which can then absorb the solubilized nutrients
Exoenzymes
are the F factor genes the first or last to be transferred in Hfr conjugation?
F Factor genes are the last to be transferred, which is why F- recipient is only very very rarely converted to F+ (generally it stays F-)
How did Falkow and Baron estimate the size of the F factor plasmid?
Falkow and Baron estimated the size of the F factor plasmid to be approximately 60 kilobases (kb) by measuring the amount of DNA in the satellite band that was found in a distinct location in the CsCl gradient centrifugation. The F factor plasmid had a different base composition than the bacterial chromosome, which allowed it to be separated and identified in this way. This experiment was a significant step in understanding the structure and function of plasmids
What was the experiment conducted by S. Falkow and L.S. Baron in 1961 to isolate the F factor plasmid?
Falkow and Baron mixed an F+ strain of E. coli with a distantly related species called Serratia marcescens. Through their experiment, they were able to transfer the F factor plasmid from the E. coli to the Serratia marcescens bacteria. To isolate the F factor plasmid, they used CsCl gradient centrifugation to separate the F factor plasmid from the bacterial chromosome based on differences in their density.
True or false: the low frequency of recombination observed for any marker in a cross (10-7) because every F+ cell can transfer any portion of the genome with low but equal probability?
False: this was one of the hypothesis by Wollman and Jacob (but not the true one)
Define exogenote
Foreign DNA that is transferred to recipient Exogenote refers to the genetic material that is acquired by a bacterial cell from an external source.
What was the significance of Hotchkiss 1950s?
Found that DNA from both penicillin-resistant and streptomycin-resistant Streptococcus pneumonia can be used to transform sensitive to resistant Streptococcus pneumonia
Who set the stage for fractionation experiments?
Fredrick Griffith
What are fungi spores
Fungi reproduce by producing spores, which are small, single-celled structures that can be dispersed by wind, water, or other means to start new fungal colonies. Fungal spores can be produced either sexually or asexually, depending on the species.
How was the Davis U-tube experiment done
One auxotroph is locked in on side of tube and another auxotroph on the other side (Each auxotroph was 180% opposite of the other meaning if one auxotroph was T-, L-, then the other auxotroph was T+,L+) The solution inside the tube was able to go back and forth b/w the two auxotrophs but with a filter that did not allow direct contact of the cells (DNA molecules could pass b/w chambers) If direct contact was not needed for conjugation then both auxotrophs would become protorophs Once he performed the experiment and isolated the auxotrophs on minimal media, he realized that neither was able to grow on the media Proved that direct contact was required.
How many cells need to have the f factor for conjugation to occur?
Only one! Cross must be F+ x F-
In specialized transduction only a specific portion of bacterial genome is transferred that is ______
Only the part of the bacterial genome that is adjacent (next to) the integration site of the prophage Remember a prophage is a type of temperate phage A prophage is a bacteriophage that has integrated its genetic material into the hosts bacterium
What is more efficient regarding genetic information transfer? Hfr or F+ x F- conjugation
If the goal is to transfer a large amount of chromosomal DNA between bacterial cells, Hfr conjugation is generally considered more efficient than F+ x F- conjugation.
What is the F' plasmid?
Imprecise excision of the F plasmid from the chromosome of an Hfr cell may lead to the production of an F' plasmid that carries chromosomal DNA adjacent to the integration site
Describe fungi dimorphism in animals
In animals fungi are typically yeast inside host and filamentous (mold) outside of host
How does generalized transduction occur?
In generalized transduction, a bacteriophage can transfer a random piece of bacterial DNA from a donor cell to a recipient cell. This can occur when the bacteriophage mistakenly packages a segment of the donor cell's DNA into its viral capsid instead of its own DNA. When this bacteriophage then infects a recipient cell, it can deliver the donor DNA into the recipient's genome, potentially conferring new genetic traits.
Describe fungi dimorphism in plants
In plants, filamentous (mold) in host and yeast outside of host
Just read but know that interrupted Hfr conjugation is a way to map genes
Interrupted mating is a technique used to map the order and relative distance between genes on a bacterial chromosome. In this technique, the conjugation process is stopped at various time intervals by physically separating the donor and recipient cells. By analyzing the transferred DNA at different time points, the order and relative distance between genes on the chromosome can be determined.
What is generalized transduction mapping?
Is a technique used to establish gene linkage and determine the relative distances between genes on a bacterial chromosome. This technique is based on the frequency of cotransduction, which is the probability that two genes will be transduced together in a single transducing particle. If two genes are located close together on the chromosome, there is a higher likelihood that they will be carried on the same DNA fragment and be transduced together. The frequency of cotransduction is therefore higher for genes that are close together than for genes that are further apart.
Once the F factor is transferred to the F- bacterium, what happens to that F- bacterium?
It becomes F+ and gains the ability to transfer the F factor to other F- bacteria. This allows for the rapid spread of the F factor and any other gens it carriers throughout a population of bacteria.
What's an Hfr cell?
It stands for high frequency recombinant cell Occasionally the F plasmid may integrate itself into the bacterial chromosome of the donor cell to produce what is known as an Hfr cell. An Hfr cell is able to transfer portions of its chromosome to a recipient cell during conjugation.
______________ devised methods to look for low frequency events that would provide evidence for genetic recombination, such as the transfer of genetic material from one bacterial cell to another through conjugation.
Lederberg
Who discovered bacterial conjugation ?
Lederberg and Tatum (1946 recombination experiments)
The identification of the F fertility factor in male (donor) strains was accomplished by two independent experiments conducted by ________________, and ___________.
Lederberg and Tatum. And William Hayes
Who discovered Transduction (generalized transduction)
Lederberg and Zinder Attempted to analyze conjugation in Salmonella typhimurium Initially thought they observed evidence of conjugation between two multiply auxotrophic strains Further experiments revealed the mechanism responsible for genetic transfer was a form of transduction, which they termed generalized transduction
What colony got transformed to what in Fred Griffith experiment?
Living R bacteria + heat-killed S bacteria====== has been transformed to living S
What are the two different life cycles of phages upon infecting a bacterial cell
Lytic cycle and the lysogenic cycle
In F' conjugation what is the recipient cell called?
Merozygote
What are cilia?
Microscopic, hair-like structures that protrude from the surface of certain cells in many organisms.
Fungi are found where?
Moisture, the appropriate temperature and suitable organic nutrients are present
_________ exist primarily as filamentous hyphae
Molds
filimentous fungi are known as
Molds
What are two extra things Griffith found out during his experiments ?
Mouse is not essential for transformation process Cultivating living R in the presence of S cell-free extract (the goodies inside a lysed cell) produces the same result
In Hfr conjugation do the recipient cells have the ability to become F+ after completion? Why or why not?
NO, This is because during Hfr conjugation, only a portion of the F plasmid DNA is transferred to the recipient cell along with the chromosomal DNA. Thus the recipient cell does not receive the entire F plasmid and is not able to become a complete F+ cell.
Can the F factor cause the recipient bacterium to become auxotrophic?
NO, the transfer of the F factor plasmid does not typically result in any changes to the recipient cell's ability to synthesize essential nutrients
During F' conjugation, does the F' plasmid become incorporated into the chromosomal DNA?
No chromosomal integration
Is E.coli naturally competent?
No, E.coli must be treated with CaCl2 (calcium chloride) in order to undergo transformation
Does the entire donor chromosome of Hfr cells become donated to the recipient bacteria?
No, the process is interrupted before the entire chromosome can be transferred
Do transducing phages contain the phage genome?
No, transducing phages involved in generalized transduction do not contain a phage genome.
Define merozygote
Recipient cell that is partially diploid as result of transfer process. partially diploid," because it has two copies of that particular gene or DNA (that came from foreign DNA), but only one copy of everything else in its genome (that did not come from foreign DNA). When the the transferred genetic material integrates into the recipient cell's chromosome, the resulting cell is referred to as merozygote.
What does low frequency of recombination mean?
Refers to the low observed rate of genetic recombination between two bacterial strains during mating experiments.
Rubisco enzyme
Ribulose-1,5-bisphosphate carboxylase oxygenase Considered the most abundant protein on Earth Catalyzes the addition of CO2 to Ribulose 1,5 bisphosphate (CO2 fixation)
Lederberg adapted the reasoning used by ________ and ______ in their discovery of the jackpot nature of motion to examine genetic recombination
Salvador's Luria and Max Delbruck
Describe fungi dimorphism
Some fungi can change from yeast form to mold (filamentous form) A yeast-filamentous shift
Specialized transduction only occurs with ______________
Specialized transduction occurs only with temperate phages that have established lysogeny Occurs when prophage is incorrectly excised.
What is the bacteriophage called when it does not immediately undergo the lytic cycle
Temperate
Are fungi mainly terrestrial or aquatic
Terrestrial
What did Wilson say in 1925 regarding the Avery-Macleod-McCarty experiment?
That since proteins had so much more diversity then nucleotides, then the differences between different chromosomes depend on their protein components and not upon their nucleic acids
The Amoebozoa supergroup is a diverse group of unicellular eukaryotic organisms that contains what subgroup?
The Eumycetozoa group is a sub-group within the Amoebozoa supergroup
What is the F (fertility) factor?
The F factor is a piece of DNA that allows bacteria to transfer genetic material, including plasmids and genes, from one bacterium to another during conjugation. The F factor is a self-transmissible plasmid, which means that it can replicate and transfer itself from one bacterium to another during conjugation. Carries the genes necessary for sex pilus formation and plasmid transfer
After the IV secretion apparatus forms and creates a channel b/w the donor and recipient bacterium, what occurs next?
The F factor plasmid must first replicate within the F+ donor cell using a mechanism called rolling circle replication. During the process, a single strand of DNA within the plasmid is displaced and transferred to the F- recipient cell through the Type IV secretion apparatus
In F+ x F- mating does the F plasmid become integrated into the bacterial chromosome of the recipient?
The F plasmid in the F+ cell does not integrate into the host chromosome of the F- cell and instead exists as a separate, self-replicating circular piece of DNA.
What did Hfr mapping experiments discover in terms of the F factor incorporated into the Hfr donor cell?
The data led to the idea that Hfr strains contain the F+ factor integrated in different orientations in different regions of the genome in each different Hfr strain
Before 1943, why were experiments regarding genetic recombination not convincing?
The events occurred at too low a frequency to be detected by the methods used at the time
What are hyphae?
The filaments of a mold One important characteristic of hyphae is that they are often coenocytic, meaning that they contain multiple nuclei within the same "cellular compartment." This is in contrast to the cells of most other eukaryotic organisms, which have a single nucleus per cell. In coenocytic fungi, the nuclei can divide and replicate independently of one another, which allows the fungus to grow rapidly and adapt to changing environmental conditions. Some hyphae are also divided into distinct compartments by septae, which are thin walls that separate one part of the hypha from another.
How was the first Hfr donor strain discovered?
The first Hfr donor strain was discovered in 1950 by Italian geneticist Luigi Luca Cavalli-Sforza using a chemical called nitrogen mustard to induce mutations in bacterial cells. He found that one strain of bacteria showed a 1000-fold increase in the number of recombination that were able to grow on minimal media.
What do Competence-specific, single- strand DNA-binding protein do?
The main function of competence-specific SSBs is to bind to single-stranded DNA (ssDNA) that is generated during the process of DNA uptake and protect it from degradation by nucleases. Also can assist in integration of the single stranded DNA into the bacterial genome
What is the most common to least common form of horizontal gene transfer
The most common is conjugation The second most common is transduction The least common is transformation
What are the nine outer tubules of cilia?
The nine outer tubules of cilia are arranged in a circular pattern around the central pair of inner tubules.
What does Excision or Loop out mean in regards to Hfr conjugation?
The process by which the F factor loops out of the chromosome and resumes its independent existence as a plasmid. Known as the F' plasmid If the integration of the F factor into the chromosome is reversed, the F factor can "loop out" of the chromosome and become a plasmid, carrying chromosomal DNA with it to create an F' plasmid.
What occurs when the DNA from a transducing phage does not incorporate into the recipient chromosome in transduction?
The transduced DNA in abortive transductants is not stably transferred, and the recipient cell will lose the transduced genes over time, so it's only a temporary stage. However, genes within the transduced DNA can still be expressed at this time.
What is bacterial conjugation?
The transfer of genes between bacteria that depends on 1) direct cell to cell contact mediated by the F pilus (aka sex pilus, aka conjugation pilus) 2) A type of IV secretion system.
Where does the transferred DNA of Hfr conjugation go in the recipient cell?
The transferred DNA then begins to recombine with the recipient cell's chromosome, replacing any homologous regions of DNA that may be present.
What occurs after the the F factor replicated single strand is transferred into the recipient cell?
The transferred strand serves as a template for the recipient cell to produce a complementary strand, resulting in the formation of a double-stranded F factor plasmid within the recipient cell.
What are the two inner tubules of cilia?
The two inner tubules of cilia are complete core tubules located in the center of the cilia and are connected to each other by radial spokes.
What provided insight into the structure of the E.coli genome?
The use of multiple Hfr strains in mapping experiments
Idk if this is high yield but: What did Wollman and Jacob do to create a genetic map of the E. coli chromosome?
They crossed many genetically mapped F- strains with an Hfr strain called Hfr Hayes, which had a known integration site for the F-factor on its chromosome. By measuring the time it took for different genetic markers to be transferred from the donor Hfr cell to the recipient F- cell, they were able to determine the relative order and distance between the markers on the chromosome. The result of their experiment was a linear map of the E. coli chromosome, showing the relative positions of the genetic markers along the length of the chromosome. the term "genetic map" refers to a diagrammatic representation of the relative positions of genes or genetic markers along a chromosome or genome.
How did lederberg resolve the problem with auxotrophic E.coli spontaneously reverted back to prototrophic?
To address this problem, Lederberg proposed the use of multiple auxotrophic markers in experimental designs. By using multiple markers, the probability of simultaneous reversion to prototrophy is much lower, making genetic analysis more feasible.
What are two objections to the Avery, Macleod, McCarty and Macleod Results?
Trace amounts of proteins beyond the limits of detection was present with DNA (co purifying) and this protein was the genetic material DNA was only the scaffold but the protein was protease-resistant
What is the name of the bacteriophage that has incorporated some of the host DNA into its head?
Transducing phage
In horizontal gene transfer in prokaryotes, are genes transferred to the same or different species?
Trick question but genes can be transferred to the same or different species.
True or False: Is the low frequency observed because there are different Hfr mutants hidden in the F+ population, each able to transfer a different region of the genome with high probability?
True: the other hypothesis by Wollman and Jacob
Difference between specialized and generalized transduction
Unlike specialized transduction, which transfers specific genes located adjacent to the prophage insertion site, generalized transduction packages a random piece of bacterial DNA.
______________and __________ are two classes of fungi that are important plant pathogens, causing diseases known as "rusts" and "smuts," respectively.
Urediniomycetes and Ustilaginomycetes
Generalized transduction is a form of transduction that occurs during the _________ cycle of certain bacteriophages
lytic
Mycelium
mass of hyphae (branched)
Whats a prototroph bacteria?
prototrophs are strains that are able to synthesize all of the essential nutrients they need for growth and reproduction. They were originally identified based on their ability to grow in minimal medium, which contains only the basic nutrients required for microbial growth. Derived from "protos" (first/minimal) and "trophe" (food)
What does prophage mean
refers to the state of a bacteriophage genome when it integrates into the chromosome of a bacterial cell and replicates passively along with the bacterial chromosome as a part of it. Replicates passively means that the phage DNA is not actively producing new phage particles but is simply copying itself every time the bacterial DNA replicates. Prophage= "lysogenic phage" However, when the conditions become favorable, the prophage can exit the chromosome and enter the lytic cycle, resulting in the production of new phage particles and cell lysis. ——— Exposure to stress such as UV light can trigger excision from host chromosome
Mycotoxicology is
study of fungal toxins which are mycotoxins and their effects
Mycology is
study of fungi
in order for a bacterium to be able to transfer genetic material to another bacterium through conjugation, it must have ____________________.
the F factor present in its DNA (in one parent in the cross)
What does wild type mean?
the most common, non-altered form of a gene (normal genetic makeup for the particular species)
What did Harriet Taylor discover? 1949
to restore the ability to make capsules when the DNA was added from an organism that has the ability to make capsules Extremely rough + Rough bacteria ======= transforms into Rough bacteria R bacteria + S bacteria ====== transforms into S bacteria Extremely Rough + S bacteria ====== transforms into Rough bacteria
Molecular biologist exploit _____________ as "delivery vehicles" to clone DNA
transducing phage particles
What is bacterial transformation?
uptake of naked DNA by a competent cell followed by incorporation of the DNA into the recipient cell's genome
Transduction is a common mode of horizontal gene transfer in bacteria, which is mediated by ___________
viruses called bacteriophages or phages.
What is the name of unicellular fungi
yeast
Fungi include what three categories?
yeasts, molds, mushrooms
Describe the difference between lytic and lysogenic cycle
—- In the lytic cycle, the phage hijacks the bacterial cell machinery to produce multiple copies of itself, leading to the lysis (bursting) of the bacterial cell and the release of new phage particles. In contrast —-during the lysogenic cycle, the phage genome integrates into the bacterial chromosome and becomes a prophage. The prophage replicates with the bacterial chromosome and is stably inherited during cell division. (Such phage do not immediately begin their lytic cycle after entering the host)
How is the F factor transferred?
When a bacterium with the F factor comes into contact with a bacterium lacking the F factor, the F factor can be transferred through a conjugation pilus that connects the two cells. The F factor is transmitted by physical contact between the donor and recipient cells
Describe how the recipient cell during F' conjugation becomes a merozygote
When a cell receives an F-plasmid, it can become partially diploid for the genes carried by that plasmid. This means that it now has two copies of those genes: one on the original chromosomal DNA and one on the new F-plasmid. The cell is called a merozygote, which is like a partial diploid cell
What's an auxotroph bacteria
Word used to describe type of bacterial strain They were originally identified because they require a specific nutritional source that is present in a complete medium but not in a minimal medium. Auxotrophs are strains that have lost the ability to synthesize certain essential nutrients, such as amino acids or vitamins, and require these nutrients to be provided in their growth medium. Derived from "aux-" (increase) and "trophe" (food)
What organisms are fungi
Yeasts, molds, and mushrooms
Can plasmids be taken up by bacteria through the process of transformation?
Yes Once the plasmid has been taken up by the bacteria, it can replicate independently of the bacterial chromosome.
Are the tra genes still functional of the F plasmid when it is incorporated into the chromosomal DNA?
Yes the tra genes are apart of the F factor that are necessary for conjugation, they are still functional and present.
Was Hershey surprised that DNA was the genetic material instead of proteins?
Yes, even Hershey himself believed that protein would be the result of his experiment
Is competence of bacteria different in different stages of the cell cycle?
Yes, the competence of the cell is affected by the stage of the cell cycle. the cells are most competent for transformation in the earlier stages of cell division
Does increasing the amount of DNA extract for competent bacteria increase the uptake?
Yes, the receptors are saturable — the more DNA added, the greater the uptake by the cells — when the receptors are saturated, adding more DNA does not affect the uptake
For bacteria that are competent, are there receptors on the cell surface that are responsible for binding to DNA and facilitating its entry into the cell?
Yes, there are DNA accepting receptors on the cell surface of competent cells (thats how they pick up DNA from the environment)
Are fungi aerobic or anaerobic?
aerobic (some are facultative anaerobes) (Obligate anaerobic fungi) are found only in rune of cattle
In microbiology, the terms "___________" and "___________" are used to describe different types of microbial strains based on their nutritional requirements.
auxotroph prototroph
During the lytic cycle, the phage infects the bacterial cell and replicates its own genome while also doing what to the host genome?
breaking down the host genome into fragments. Accidentally, some of these fragments of bacterial DNA may be packaged into phage particles instead of the phage genome, producing generalized transduction particles.
What is cAMP
cyclic adenosine monophosphate, a signaling molecule in many organisms
Mycoses is
diseases caused by fungi
Define endogenote
genome of recipient The endogenote refers to the DNA (genome) that is originally present in the bacterial
Mycorrhizae fungi
-live in intimate contact with the roots of plants
Describe Lederberg experiment E.coli genetic cross to discover conjugation?
1) Two Auxotrophic E.coli are grown together overnight ————Controls of each are grown separately as well (One requires methionine in the media to grow) (One requires proline in the media to grow) 2) Collect organisms by centrifugation And the are put on minimal medium to grow 3) If the organisms grow on minimal media then recombination has occurred which means conjugation has occurred. The yield received by this experiment is one colony formed for every 10^7 bacteria plated (low yield but normal for this type of experiment) To ensure that the colonies formed are a result of genetic exchange and not just the individual strains, controls for reversion are conducted. This involves plating each strain separately on minimal medium to see if they can grow independently.
Avery-MacLeod-McCarty experiment?
1) Removed proteins, lipids, polysaccharides, RNA from the S cell extract 2) saw no difference and the the rough colony still turned into a smooth colony and the mouse died 3) Removed DNA and the rough colony stayed a rough colony and the mouse lived
What genes in the f plasmid encode proteins that are components of the type IV secretion system? What about the gene that encodes pilin protein?
1) TraK, traB, TraP 2) TraA
What are the steps of generalized transduction from the picture on slides
1) phage infects bacteria 2) Host DNA is hydrolyzed into pieces, and phage DNA and proteins are made 3)Phages assemble; occasionally a phage carries a piece of the host cell chromosome 4) cell lysis 5) transducing phage injects its DNA into a new recipient cell 6) The transduced DNA is recombined into the chromosome of the recipient cell. This results in the recipient bacteria being His-, Lys- to become His+, Lys+ after transduction (for example)
What two things did Davis say/prove regarding Bacterial conjugation
1) showed that direct contact of cells is essential 2) showed that gene transfer is polar (no reciprocal) ————-This means that only one of the two cells involved in the conjugation event actually donates genetic material, while the other cell only receives genetic material.
Give me three main points about transduction
1) transduction is the transfer of bacterial genes by viruses (phages) 2) Bacterial genes are incorporated into the phage genome by "errors" that occur as the phage propagates 3) The phage that carry the bacterial DNA transfer that DNA to a new bacterium upon infection
Dunedin walks in the ________ direction along the microtubule
(-)
In transduction if the DNA does not integrate into the recipient chromosome (to become stable), the recipient is called an __________
"abortive transductant."
Generalized transduction just read (entire process)
Generalized transduction is a form of transduction that occurs during the lytic cycle of certain bacteriophages. Both virulent and some temperate phages can carry out generalized transduction. During the lytic cycle, the phage infects the bacterial cell and replicates its own genome while also breaking down the host genome into fragments. Accidentally, some of these fragments of bacterial DNA may be packaged into phage particles instead of the phage genome, producing generalized transduction particles. Unlike specialized transduction, which transfers specific genes located adjacent to the prophage insertion site, generalized transduction packages a random piece of bacterial DNA. Consequently, the transduced DNA may contain any gene or genomic region. When the transducing phage infects a new bacterial host, it injects the transduced bacterial DNA. The injected bacterial DNA can integrate into the recipient bacterial chromosome, potentially providing new genetic traits to the recipient bacterial cell. Generalized transduction is an important mechanism for horizontal gene transfer in bacteria and can contribute to the spread of antibiotic resistance genes among bacterial populations.
What organism is apart of chloroplastida?
Green algae Grows in fresh/salt water, soil and in/on other organisms
What is Hfr mapping?
Hfr mapping is a technique used to map the relative location of bacterial genes. The method is based on the observation that chromosome transfer during conjugation between an Hfr (high-frequency recombination) strain and an F- (lacking F-factor) strain occurs at a relatively constant rate. The interrupted mating experiment is used to determine the order and timing of gene transfer. The cells are harvested at specific time intervals after conjugation begins and analyzed to determine which genes have been transferred. The order in which the genes are transferred reveals their relative location on the bacterial chromosome. By analyzing the pattern of gene transfer at different time intervals, the relative location of the genes on the bacterial chromosome can be determined.
In Hfr cells, where is the fertility (F) factor located?
Hfr strains contain the F factor integrated into their chromosome. (The F plasmid integrated)
(Fred Griffith) In order for streptococcus pneumonia to be pathogenic what does it require?
Pathogenicity requires capsule S=== smooth colony formers, make capsule R== rough colony formers, no capsule Rough colony formers are mutants of smooth colony formers that do not produce a capsule
Fungi are a major cause of _____ diseases
Plant
Hershey-Chase Experiment (1952)
Used radioactive material to label DNA and protein; infected bacteria passed on DNA; helped prove that DNA is genetic material not proteins Ran 2 experiments each with a certain label: ——DNA of a bacteriophage labeled with a phosphate isotope ——Protein of a bacteriophage coat labeled with Sulfur When ran experiments: 1) They noticed most of the sulfur remained with the virus and did not enter the bacteria (= protein not inherited) 2) most of the labeled DNA from the virus was injected into the bacteria. It was also inherited and passed onto the new virus generation. (Concluded DNA was the genetic material) In this experiment, Hershey and Chase used a bacteriophage virus to infect bacteria. They labeled the viral DNA with radioactive phosphorus-32, and the protein coat of the virus with radioactive sulfur-35. The idea was to see which of these two components of the virus entered the bacterial cell during infection, and which one was responsible for directing the synthesis of new viruses. The researchers found that only the labeled DNA entered the bacterial cell, while the labeled protein coat remained outside. This suggested that the DNA was the hereditary material responsible for directing the synthesis of new viruses.
Both _______ and ______ phages can carry out generalized transduction
Virulent and temperate phages
