. A closed circular supercoiled DNA is relaxed by treatment withtopoisomerase. No matter how much enzyme is used, or how longthe experiment is run, the experimenter always finds a gel elec-trophoresis pattern indicating some DNA with one, two, and threesuperhelical turns in addition to the relaxed (nicked) circle (see fig-ure). Suggest an explanation for this observation.Nickedcircle+

DNA topoisomerases are enzymes that relieve the topological strains in the DNA by creating single or…

Answered: . A closed circular supercoiled DNA is…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter28: Dna Metabolism: Replication, Recombination, And Repair

Section: Chapter Questions

Problem 9P: Heteroduplex DNA Formation in Recombination From the information in Figures 28.17 and 28.18, diagram...

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1) Which statement below explains the trick in sanger sequencing that produces fluorescently labeled fragments at every length within a fragment? a) When synthesizing a copy of the DNA to be sequenced, a high concentration of fluorescently labeled dideoxynucleotides (ddNTPs) are used along with a low concentration of deoxynucleotides (dNTPs) to produce the chain termination events at every location in the sequence. b) When synthesizing a copy of the DNA to be sequenced, fluorescently labeled dideoxynucleotides (ddNTPs) are used instead of deoxynucleotides (dNTPs) to produce the chain termination events at every location in the sequence. c) When synthesizing a copy of the DNA to be sequenced, a low concentration of fluorescently labeled dideoxynucleotides (ddNTPs) are used along with a high concentration of deoxynucleotides (dNTPs) to produce the chain termination events at every location in the sequence. d) When synthesizing a copy of the DNA to be sequenced, fluorescently labeled…
In experiments using polymerase chain reactions (PCR), it is often more difficult to amplifythrough regions of DNA that are high in GC content versus those regions that are either lower inGC content or are AT-rich. Based on your knowledge of DNA structure, explain why.
That's the result of Gel electrophoresis of genomic DNA ( Of genomic DNA extraction experiment), please discuss the results and label and name the image to illustrate the answer? - Marker band sizes in gel: From top (well side) to bottom the bands have the following size in base-pair/bp- 6751,3652,2827,1568,1118,825,630
In Noll’s experiment , explain where DNase I cuts the DNA. Why were the bands on the gel in multiples of 200 bp at lower DNase I concentrations?
Biochemistry: Site-directed mutagenesis, in which individual amino acid residues are replaced with others, is a powerful method to study enzyme mechanisms. In experiments with particular enzyme, various lysine residues were replaced with aspartate, yielding the results summarized in the table below: Enzyme Form: Enzyme Activity (U/mg) Native enzyme: 1,000 U/mg Recombinant Lys 21 to Asp 21: 970 U/mg Recombinant Lys 86 to Asp 86: 100 U/mg Recombinant Lys 101 to Asp 101: 970 U/mg a. What might be inferred about the role of Lys 21, 86, and 101 in the catalytic mechanism of this enzyme? b. Discuss where within the enzyme one might find Lys 21 and 101. Are these residues likely to be evolutionary conserved in this enzyme? Explain c. Is Lys position 86 likely to be evolutionary conserved? Explain
Suppose that a replicative DNA polymerase had its 3′ exonuclease site 1.5 nm from the polymerase site, rather than the 3.0 nm seen in Klenow fragment. How would this change affect the fidelity of the enzyme? Why? Describe an additional change that could give this enzyme the same fidelity as Klenow fragment while retaining the 1.5-nm inter-site distance.
Homologous Recombination, Heteroduplex DNA, and Mismatch Repair Homologous recombination in E. coli leads to the formation of regions of heteroduplex DNA. By definition, such regions contain mismatched bases. Why doesnâ€™t the mismatch repair system of E. coli eliminate these mismatches?
Heteroduplex DNA Formation in Recombination From the information in Figures 28.17 and 28.18, diagram the recombinational event leading to the formation of a heteroduplex DNA region within a bacteriophage chromosome.
Although DNA polymerases require both a template and a primer, the following single-stranded polynucleotide was found to serve as a substrate for DNA polymerase in the absence of any additional DNA.3′ HO-ATGGGCTCATAGCCGGAGCCCTAACCGTAGACCACGAATAGCATTAGG-p 5′What is the structure of the product of this reaction?
Can you please help with 1a please picture with 1 graph is for question 1a) picture with 4 graphs is for question 1b) 1a) E. coli DNA and binturong DNA are both 50% G-C. If you randomly shear E. coli DNA into 1000 bp fragments and put it through density gradient equilibrium centrifugation, you will find that all the DNA bands at the same place in the gradient, and if you graph the distribution of DNA fragments in the gradient you will get a single peak (see below). If you perform the same experiment with binturong DNA, you will find that a small fraction of the DNA fragments band separately in the gradient (at a different density) and give rise to a small "satellite" peak on a graph of the distribution of DNA fragments in the gradient (see below). Why do these two DNA samples give different results, when they're both 50% G-C? 1b) If you denatured the random 1000 bp fragments of binturong DNA that you produced in question 1a by heating them to 95ºC, and then cooled them down to 60ºC and…
The enzymes ECORI and HINDIII are called "compatible" enzymes. DNA cut with these enzymes can be ligated together, but it will usually not be able to be recut with the original enzymes. If that procedure were carried out, what would the DNA sequence be?
The temperature at which a DNA sample denatures can be used to estimate the proportion of its nucleotide pairsthat are G- C. What would be the basis for this determination, and what would a high denaturation temperature for aDNA sample indicate?

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