.What does it mean to say that DNA is replicated by a semiconservative mechanism? Describe the experiment of Meselson and Stahl and how it showed that DNA replication is semiconservative

2. Dr. Kim at Ewha Research Center performed shotgun Sanger sequencing on an unknown DNA sample, and obtained the following reads (12 reads). Since the length of each read is quite short, Dr. Kim ran the original sample in a gel electrophoresis, and realized that the original DNA is just 50 base pairs long. (Please note that the resolution of gel electrophoresis is not so good. Thus, we cannot figure out the exact length of DNA using gel electrophoresis in the real world.) 1) САСТС ССAGT GTACC T 3) GGAGT CAАТC GC 5) GGCTG TGCTT GG 7) GATGG CTGTG 9) CAGTG TAССT GCA 11) TGCAA GCCGA G 2) AGCCG AGATG GCTG 4) CTGCA AGCCG A 6) CTTGG AGTCA ATCGC 8) САСТС ССAG 10) GCTGT GСТTG G 12) TGCTT GGAGT (a) Find the sequence of the original DNA (reconstruction), and align each read with the reconstructed DNA sequence. (hint: put all reads on a ppt slide, and move them around to find overlaps.) (b) Calculate coverage at each nucleotide position of the reconstructed DNA, i.e., how many reads cover that…

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36. Which is the sequence of steps used to amplify DNA with PCR during a single cycle? 1) Primers bind (anneal) to complementary sequences of the target DNA. 2) DNA is heated to a high temperature to cause denaturation (DNA is single-stranded). 3) DNA polymerase extends the 3’OH of primers to make copies of the target DNA. A) 1, 2 and 3 B) 3, 2, and 1 C) 2, 1, and 3 D) 1, 3, and 2

The correct answer for this homework problem is D because the sythase is moving that direction so it can't be the starting point, right?

2. Dr. Kim at Ewha Research Center performed shotgun Sanger sequencing on an unknown DNA sample, and obtained the following reads (12 reads). Since the length of each read is quite short, Dr. Kim ran the original sample in a gel electrophoresis, and realized that the original DNA is just 50 base pairs long. (Please note that the resolution of gel electrophoresis is not so good. Thus, we cannot figure out the exact length of DNA using gel electrophoresis in the real world.) 1) САСТС ССAGT GTACC T 3) GGAGT CAАТC GC 5) GGCTG TGCTT GG 7) GATGG CTGTG 9) CAGTG TACCT GCA 11) TGCAA GCGA G 2) AGCCG AGATG GCTG 4) CTGCA AGCCG A 6) CTTGG AGTCA ATCGC 8) САСТС ССAG 10) GCTGT GCTTG G 12) TGCTT GGAGT (a} Find the sequence of the original DNA (reconstruction), and align each read with the reconstructed DNA sequence. (hint: put all reads on a ppt slide, and move them around to find overlaps.) (b) Calculate coverage at each nucleotide position of the reconstructed DNA, i.e., how many reads cover that…

3. In the following drawing, the top strand is the template DNA, and the bottom strand shows the lagging strand prior to the action of DNA Polymerase I. Three Okazaki fragments are shown and the RNA primers (asterisks) have not yet been removed. 3'- -5' 5********** RNA primer Left Okazaki fragment ↑ RNA primer ↑ -||- Middle Okazaki fragment -||- *********** RNA primer Right Okazaki fragment -3' A. Which Okazaki fragment was made first, the one on the left or the one on the right? B. Which RNA primer would be the first one to be removed by DNA polymerase I, the primer on the left or the primer on the right? For this primer to be removed by DNA polymerase I and for the gap to be filled in, is it necessary for the Okazaki fragment in the middle to have already been synthesized? Explain why. C. Let's consider how DNA ligase connects the left Okazaki fragment with the middle Okazaki fragment. After DNA polymerase I removes the middle RNA primer and fills in the gap with DNA, where does DNA…

5. Shorthand DNA is written as antiparallel arrows with 5' and 3' ends. 3' a) What do the 5' and 3' ends signify? b) To which end are new nucleotides added when building a DNA strand?

57. You learn that a Mars lander has retrieved a bacterial sample from the polar ice caps. You obtain a sample of these bacteria and perform the same kind of experiment that Meselson and Stahl did to determine how the Mars bacteria replicate their DNA. Based on the following equilibrium density gradient centrifugation results, what type of replication would you propose for these new bacteria? band position 28060 8 8 before after 1st N₁4 after 2nd replication replication A) conservative B) semiconservative dispersive C) D) semiconservative or dispersive E) conservative or dispersive after 3rd replication

The antibiotic Cipro (ciprofloxacin) inhibits DNA gyrase found in bacteria. Why would this stop bacteria from dividing? Group of answer choices 1. DNA polymerase I could not remove RNA primers 2. Helicase would not be able to fully unwind the replication bubble due to stress in the DNA 3. Okazaki fragments would come off of the newly replicated DNA dnaA would not bind to the OriC 4. DNA Polymerase III would be halted on only the lagging strand