what is the difference between the T5 and T7 bacteriophage promoters?
113007
They are promoter sequences originally isolated from different strains of phage.   T7 uses a polymerase different from all the other T bacteriophages, so it is a totally different sequence from the T5 promoter.
29539
No, different genes are coded starting on different strands. However, one strand must be used for one protein; they cannot both be used, because RNA polymerase binds to a start codon and then must procede in the 5' to 3' direction.
491632
tritiated thymidine is a nucleotide with a radioactive label (3H)\n\nDNA synthesis requires thymidine, it's the T in the A/G/T/C that make up the genetic code.\n\nso incorporation of tritiated thymidine is a measure of DNA synthesis, or cell division.
210214
The origin of DNA replication is characterised by A-T rich region. This is because only 2 hydrogen bond are form between this base pair, compare 3 hydrogen bond form between C-G base pair. This allows the enzyme to separate the 2 DNA strands as this A-T rich region is the weakest.
1020699
First of all make sure your template is good quality. Did you extract genomic DNA, do you have a library in plasmids...(?).\nTry re-purifying your template.\n\nMaybe your template is GC-rich or has some secondary structure.\nIs your template very long?If so make sure you let the polymerase is working at the elongating temperature for enough time (1min/kb)\n\nIf you are using plasmid template try not to use too much. Don't put more than 30-40ng DNA in a reaction. \n\nCheck your primers:\n-can they form a dimer?\n-can they anneal at more than one site on the template DNA with a only few mismatches?\n-is the difference in the Tm of the two primers more than 6 C (it shouldn't;ideally they should be the same and I try not to exceed a difference of 4)?\n-do your primers end in more than 3  c or g in a row?\n-what's their Tm and GC content?Tm should not be very low (I design my primers at 56-61) and GC 40-60%.\n\nThe most strigent conditions are using as annealing temperature 2 C below the lowest Tm of the two primers. Try lower temperatures.\n\nYou can try different enzymes Taq, Pfu, Pwo, etc, even mixtures. Not all enzymes have the same processivity.\n\nYou can try different Mg+2 concentrations.\n\nThere are a lot of control experiments you can do depending on your template and primers. Eg if you have a library in a  plasmid that has sites for universal primers you can use one such primer and the other respective primer you designed in order to check if there is something wrong with the quality of your primers. \n\nIf everything is perfectly designed and you've tried evreything but still get a very faint (but of correct size) band, gel purify it and use it as a template for a new PCR. In this case you'll have a very high chance of getting mutations so you'll need to use a high fidelity enzyme like Pwo or Pfu turbo and of course sequence a lot till you get a correct clone.
677350
Wow, this answer is gonna be a long one...   There are numerous studies of the charting of the positions of genes on a DNA molecule or chromosome and the distance between genes of Escherisia Coli. It basically comes down to good old conjugation and transduction.  Having sequenced the E. coli K-12 genome, scienctists are creating a knockout of every gene, a clone of every ORF, and an extensive gene expression data set under a variety of physiological conditions. These clones and data sets are made available freely to the community.  Scienctists have also sequenced six additional enterobacterial strains which are pathogens closely related to E. coli K-12, and many plasmids. The comparative genomics aim of this effort is to characterize the gene pool of horizontally transferred elements and virulence determinants known as the pathosphere.\n\nI put a reference on it so be sure to check it out yourself. \n\nA mutator gene, mutD5, whose phenotype is conditional, has been identified in Escherichia coli. By P1 transduction it has been shown to lie at about 5.7 min on the chromosome, being co-transduced with proA and argF. In rich medium, streptomycin- and nalidixic acid-resistant mutation frequencies are 50 to 100 times higher than those in minimal medium. In minimal medium, the mutD5-induced mutation frequencies are still 50 to 100 times above co-isogenic wild-type (mut+) levels. Similar results were obtained with all markers tested. Mutant frequencies can be raised by thymidine in the medium at concentrations as low as 0.04 μM, or by the endogenous generation of thymidine from thymine plus a deoxyribosyl donor. Deoxyadenosine, various ribonucleosides, thymine, and 2-deoxyribose do not stimulate mutation. None of these effects are related to growth rate, since growth rate and mutation rate can be decoupled completely.\n\nThe gntP gene, located between the fim and uxu loci in Escherichia coli K-12, has been cloned and characterized. Nucleotide sequencing of a region encompassing the gntP gene revealed an open reading frame of 447 codons with significant homology to the Bacillus subtilis gluconate permease. Northern (RNA) blotting indicated that the gntP gene was monocistronic and was transcribed as an mRNA with an apparent molecular size of 1.54 kb. The transcriptional start point was determined by primer extension analysis. The gntP gene was found to be under catabolite repression and was not induced by gluconate. Also, expression seemed to be stringently controlled. Several observations indicated that the GntP protein is an inner membrane protein; it contains characteristic membrane-spanning regions and was isolated predominantly from the inner-membrane fraction of fractionated host cells. A topology analysis predicted a protein with 14 membrane-spanning segments. The inability of a mutant strain to grow on gluconate minimal medium could be relieved by introduction of a plasmid encoding the gntP gene. Finally, the kinetics of GntP-mediated gluconate uptake were investigated, indicating an apparent Km for gluconate of 25 microM.
489439
The short answer is that it is virtually impossible.\n\nThe example you are citing is quite an unusual case in which Corynebacterium diphtheriae produces diphtheria  toxin only when it is infected by a particular phage β, and this is because the toxin-encoding gene is carried by the phage (bacteria targetted virus) and not Corynebacterium diphtheriae itself.\n\nThe phage gains entry to a cell in the same way as any virus - by adhering to, and using to it's advantage particular surface proteins.  This is why HIV can only infect helper T-cells - it gets in by adhering to the CD4 receptor which is specific to these cells.  If any other cell in the body expressed this receptor, they too would be vulnerable to HIV infection.  But they don't.\n\nSo HIV can only infect cells expressing CD4.  So why is it only VIRTUALLY impossible, and not COMPLETELY impossible?  Well, because HIV is a retrovirus, so relies on the Reverse Transcriptase enzyme to replicate it's genome.  The replication is so poor, that mutation occurs on a MASSIVE scale.  A person infected with HIV will typically have 10,000 strains of the same virus!!  As it mutates so quickly, it is argueably just a matter of time before it randomly acquires the ability to infect a bacterium which will after all be more likely to be present in the body of an individual who is immunocompromised with HIV in the first place.\n\nNote:\nThe answer above stating that the HIV virus has an RNA-based genome is true, but completely irrelevant.  Most virusus use RNA rather than DNA, and this has no bearing on their capacity for lysogenic conversion.
109201
Restriction enzymes- they cut the phage's DNA so that the instructions within the DNA don't make any sense anymore and can no longer harm the bacteria. \n\nScientists are now using these restriction enzymes in laboratories to duplicate it in biotechnology testing
439627
It's a strain designation.  BL21 is deficient in a protease, and DE3 can be used with vectors containing the CcdB gene, which is toxic to other bacteria.
703972
The main question is: do you want to make transient or stable transfection. If you want to do stable transfections, then you will need a selective marker such as resistance to G418. \n\nSome vectors also code for a fluorescent protein such as GFP or add a tail to your protein such as a His Tag. This helps for the visualization of your protein or the purification but beware of potentially inactivating additions.\n\nYou will always have a polycloning site so what you want to find is a set of enzymes that you have in the lab in a good amount and work with them. Find the vectors that have their restriction site for the insert.\n\nAs for the promoter of use, ask around in the lab for what works the best with your cell line. It's not such a big choice.
490917
The phenotype is the physical expression of the genotype. In bacteria transformed with the pBLU plasmid and plated on the growth media containing IPTG and X-Gal will grow as either white colonies or blue colonies. pBLU is a plasmid that contains part of a gene called beta-galactosidase. The portion of the plasmid that contains this gene is called the multiple cloning site (MCS). (If you want to introduce foreign DNA into the plasmid, this is where you would introduce it.) The plasmid also has a gene for antibiotic resistance. The bacteria you use for transform with this plasmid must not already have this type of antibiotic resistance. If the bacteria are transformed with pBLU and plated on media with anibiotics only the bacteria that recieved the plasmid will grow. Those that were not transformed will die. If no DNA was inserted into the MCS of the plasmid then the for producing beta-galactosidase will be intact. This gene is called Lac Z. The transcription of this gene must be induced with a chemical called IPTG. So if the agar plate contained IPTG then the Lac Z gene will be induced and the protein beta-galactosidase will be produced. If this protein is produced it will cleave the chemical X-Gal (which was also on the plate) causing the X-gal to change from clear to blue.This causes the colonies to have a blue phenotype.\nIf the Lac Z gene was interrupted by foreign DNA in the MCS then no beta-galactosidase will be produced and the colonies will grow white.
392177
some bacteriophages were radiolabelled with radioactive phosphorous and sulhur. the sulphur bound to the external  protein coat hile the phosphorous bound to the nucleic acid inside. now, these pahges were allowed to infect a bacterial colony. the infected bacterial colony was then separated and subject to centifugation. it revelaed that while the radioactive sulphur was leftbehind in the phages, the bacterium had contracted the radioactive phosphorous. it was suggested that this was because once the phage infected the bacterium, they transfered their DNA into the bacterium. this is called transformation. this has now been verified by other methods. transformation is a very important method for genetic mutation studies.
424788
I see the mRNAs degrade faster than the rRNA. Not sure of tRNAs
62552
DNA is in every cell, but not every gene is expressed in every cell.  The way that the cell controls which genes are activated and which aren't is through DNA-binding molecules called repressors and promoters.  A promoter binds to DNA near a gene and causes transcription of the gene to make mRNA that will go on to serve as a template for protein synthesis.  Conversely, a repressor can bind to a gene and prevent the transcription of that gene into an RNA template (usually depending on conditions in the cell at the time, like chemical messengers or availability of nutrients, etc.).
848007
You get a continuous and discontinuous strand because DNA polymerase only makes DNA in 1 direction (5` to 3`).  The continuous strand is in that orientation anyway, so you get a nice long replication.  The opposit strand is oriented 3` to 5` relative to the polymerase, so the replication has to be broken down into multiple, short, 5` to 3` segments so that replication can occur within the same polymerase macromolecule.\n\nI had to mention  DNA polymerase, it's really impossible to explain this without saying something about how it works :P I did leave out RNA primers though!  If anyone else is curious, the RNA primers are the site of the initiation of replication of each little Okazaki fragment.
1140133
The four nucleotide bases, the building blocks of every piece of DNA, are represented by the letters A, C, G, and T, which stand for their chemical names: adenine, cytosine, guanine, and thymine. The A on one strand always pairs with the T on the other, whereas C always pairs with G. The two strands are said to be complementary to each other. \n\nTo copy DNA, polymerase requires two other components: a supply of the four nucleotide bases and something called a primer. DNA polymerases, whether from humans, bacteria, or viruses, cannot copy a chain of DNA without a short sequence of nucleotides to "prime" the process, or get it started. So the cell has another enzyme called a primase that actually makes the first few nucleotides of the copy. This stretch of DNA is called a primer. Once the primer is made, the polymerase can take over making the rest of the new chain. \n\nA PCR vial contains all the necessary components for DNA duplication: a piece of DNA, large quantities of the four nucleotides, large quantities of the primer sequence, and DNA polymerase. The polymerase is the Taq polymerase, named for Thermus aquaticus, from which it was isolated. \n\nThe three parts of the polymerase chain reaction are carried out in the same vial, but at different temperatures. The first part of the process separates the two DNA chains in the double helix. This is done simply by heating the vial to 90-75 degrees centigrade (about 165 degrees Fahrenheit) for 30 seconds. \n\nBut the primers cannot bind to the DNA strands at such a high temperature, so the vial is cooled to 55 degrees C. At this temperature, the primers bind or "anneal" to the ends of the DNA strands. This takes about 20 seconds. \n\nThe final step of the reaction is to make a complete copy of the templates. Since the Taq polymerase works best at around 75 degrees C (the temperature of the hot springs where the bacterium was discovered), the temperature of the vial is raised. \n\nThe Taq polymerase begins adding nucleotides to the primer and eventually makes a complementary copy of the template. If the template contains an A nucleotide, the enzyme adds on a T nucleotide to the primer. If the template contains a G, it adds a C to the new chain, and so on to the end of the DNA strand. This completes one PCR cycle.  \n\nIf Instead of G if A gets added to C, then its called as mismatch...or mutation which DNA come over by repair mechanism...\n\nhope this helps!!!
857765
In the monomer of DNA, the carbon number of deoxyribose sugar component (circular structured sugar with 5 Carbons) is marked as the first C binding to the Nitrogen base (A, T, G or C), and the 5th C binding to the phosphate group (PO4). \n\nThe 3' and 5' is called basing on the 3rd and 5th carbon in the deoxyribose molecules. DNA polymerization is like this: and individual monomer's phosphate group (which is bound to the 5th C) is added to the 3rd C of the previous monomer in the polymerized chain. The polymerization only occurs in this direction, no reverse direction (no addition of 3rd C of an individual monomer to the phosphate group bound to a monomer in a polymerized chain. That's why they say the DNA polymerization is in 5' to 3' direction.\n\nYou can go to this link to see a picture of the monomer structure and the polymerization: http://cmgm.stanford.edu/biochem/biochem201/Slides/DNA%20Structure/004%20DNA%20Covalent%20Structure.JPG