Meselson-Stahl Experiment showed thatDNA replication is semi-conservative. In theexperiment, DNA was originally labeledwith ¹5N. Then ¹5N-labeled DNA wasduplicated in the presence of ¹4N-nucleotides. It was found that the second-generation daughter DNA (after two roundsof replication) consists ofall ¹4N-DNAO b. 50% of hybrid 15N-¹4N DNA and 50% ¹5N-DNAall 15N-DNAd. 50% of hybrid ¹5N-¹4N DNA and 50% ¹4N-DNA15all hybrid ¹5N-14N DNAa.C.e.

During DNA replication, each polynucleotide strand serves as a template for the production of a…

Answered: Meselson-Stahl Experiment showed that…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Similar questions

In the experiment of Mesel- Question 3 son and Stahl on DNA replication, if the cells are cultured for many generations in a medium containing heavy nitrogen (N 15) and thereafter transferred to a medium containing only light nitrogen (N 14), what percentage of double- stranded DNA is composed of two heavy chains after one generation? A 25 B 75 C 0 D 50 E 100
On paper, replicate the following segment of DNA: 5’ A T C G G C T A C G T T C A C 3’ 3’ T A G C C G A T G C A A G T G 5’a. Show the direction of replication of the new strands and explainwhat causes lagging and leading strands to show different patternsof replication.b. Explain how this is semiconservative replication. Are the newstrands identical to the original segment of DNA?
When DNA replication was investigated by using heavy, N15 DNA to mark the original molecules, and light, N14 DNA to mark the newly synthesized molecules, one band was found in the middle of the centrifuge column after one round of replication, and two bands were found (middle and top of column) after 2 rounds of replication. Imagine that after 1 round of replication 2 bands were found, one at the bottom and one at the top of the centrifuge column. In that case, what model of DNA replication would have been supported? The dispersive model The conservative model The Franklin model The semi-conservative model
On further analysis of the DNA described in conceptual questionC21, you discover that the triplex DNA in this alien organism iscomposed of a double helix with a third strand wound within themajor groove (just like the DNA in Figure shown). How would youpropose that this DNA is able to replicate itself? In your answer,be specific about the base-pairing rules within the double helixand which part of the triplex DNA would be replicated first.
. E. coli chromosomes in which every nitrogen atom is labeled (that is, every nitrogen atom is the heavy isotope15N instead of the normal isotope 14N) are allowed to replicate in an environment in which all the nitrogen is 14N.Using a solid line to represent a heavy polynucleotidechain and a dashed line for a light chain, sketch each ofthe following descriptions:a. The heavy parental chromosome and the productsof the first replication after transfer to a 14N medium,assuming that the chromosome is one DNA doublehelix and that replication is semiconservative.b. Repeat part a, but now assume that replication isconservative.c. If the daughter chromosomes from the first divisionin 14N are spun in a cesium chloride density gradientand a single band is obtained, which of the possibilitiesin parts a and b can be ruled out? Reconsider theMeselson and Stahl experiment: What does it prove?
Draw a diagram of replication that is occurring at theend of a double-stranded linear chromosome. Showthe leading and lagging strands with their primers.(Indicate the 5′ and 3′ ends of the strands.) What difficulty is encountered in producing copies of bothDNA strands at the end of a chromosome?
Richard Boyce and Paul Howard-Flanders conducted an experimentthat provided biochemical evidence that thymine dimers areremoved from DNA by a DNA repair system. In their studies, bacterialDNA was radiolabeled so the amount of radioactivity reflectedthe amount of thymine dimers. The DNA was thensubjected to UV light, causing the formation of thymine dimers. When radioactivity was found in the soluble fraction, thymine dimershad been excised from the DNA by a DNA repair system.But when the radioactivity was in the insoluble fraction, the thyminedimers had been retained within the DNA. The following tableillustrates some of the experimental results involving a normalstrain of E. coli and a mutant strain that was very sensitive to killingby UV light: Explain the results found in this table. Why is the mutant strainsensitive to UV light?
In the Meselson-Stahl experiment on DNA replication, what fraction of the DNA was composed of one light strand and one heavy strand ("hybrid") after one generation of growth in medium containing 14N? After two generations of growth in a medium containing 14N? What fraction of hybrid DNA is expected after n generations of growth in a medium containing 14N?
Imagine you have three test tubes containing identicalsolutions of purified, double-stranded human DNA.You expose the DNA in tube 1 to an agent that breaksthe sugar-phosphate (phosphodiester) bonds. Youexpose the DNA in tube 2 to an agent that breaks thebonds that attach the bases to the sugars. You exposethe DNA in tube 3 to an agent that breaks the hydrogen bonds. After treatment, how would the structuresof the molecules in the three tubes differ?
(d) Write down the sequences of the templates that would give the tetranucleotides shown in I and II. In each case, label the 5' and 3' ends and indicate which template base is used first. (e) What difference would it make to bidirectional DNA replication if both modes of chain extension were equally favourable? I II
Reiji and Tuneko Okazaki conducted a now classic experiment in1968 in which they discovered a population of short fragmentssynthesized during DNA replication. They introduced a shortpulse of 3H-thymidine into a culture of E. coli and extracted DNAfrom the cells at various intervals. In analyzing the DNA aftercentrifugation in denaturing gradients, they noticed that as theinterval between the time of 3H-thymidine introduction and thetime of centrifugation increased, the proportion of short strandsdecreased and more labeled DNA was found in larger strands.What would account for this observation?
Which of the following statement(s) is/are false/incorrect? You may select multiple options, if necessary. ☐ Experiments support bidirectional movement of multiple replication forks at eukaryotic chromosomes. O Mg++ ions play important roles during DNA synthesis Synthesis of DNA is semi-conservative ✔ Beta clamp reduces DNA polymerase processivity ✔ DNA polymerase III uses ATP as a source of energy to drive the polymerization reaction forward O Tautomers enhance chances of correct nucleotide incorporation during DNA synthesis

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