Chapter 5 and 6 quizzes

Chapter 5 and 6 quizzes - Chapter 5 1. During the Sanger...

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Chapter 5 1. During the Sanger dideoxy sequencing method of determining the sequence of DNA, the purpose of the dideoxy nucleotide is a. to contain a fluorescent or radiolabeled group to be used in the detection of DNA fragments of different sizes following electrophoresis. b. to terminate the process of DNA synthesis in a controlled fashion. c. to serve as a primer for the initiation of synthesis of newly formed DNA Correct. The absence of a 3'-OH group means that one a dideoxy nucleotide is incorporated into a growing chain, no further nucleotides can be added. 2. In constructing an oligonucleotide probe based on information from a protein's sequence, one often chooses (if possible) regions of a sequence containing tryptophan or methionine residues. Why? a. The synthesis of most proteins starts with methionine or a derivative thereof, so a methionine codon assures one will start at the beginning of the gene. b. These two amino acids are both encoded by multiple codons such that the degeneracy of the genetic code makes it possible for a number of sequences to recognize and bind to the target sequence. c. As these two amino acids have only one codon, the oligonucleotide probe will have a greater specificity for the DNA fragment being sought. Correct. The more precisely the sequence of the probe matches that of the target sequence, the fewer false positives one will encounter. 3. Following digestion of a DNA sample with restriction enzymes and separation of the resulting fragments by electrophoresis, one often uses DNA probes and a blotting procedure to identify the fragment containing the gene of interest. This process is known as a. Southern blotting b. Northern blotting c. Western blotting Correct. Probing DNA fragments with DNA probes is an approach developed by Edwin Southern. 4. The process of PCR (polymerase chain reaction) would not be possible were it not for the use of a DNA polymerase from a thermophilic bacterium. Why? a. The thermophilic DNA polymerase has a temperature optimum of 72C. b. The thermophilic DNA polymerase must be stable at the high temperatures necessary to separate the two strands of DNA c. The thermophilic DNA polymerase prevents the DNA from separating into two strands, maintaining the double helical structure at the high temperatures used in PCR. Correct. The separation of DNA strands is normally done at 95C. The polymerase used must be stable at
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This homework help was uploaded on 04/17/2008 for the course CHE 312 taught by Professor Disney during the Spring '08 term at SUNY Buffalo.

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Chapter 5 and 6 quizzes - Chapter 5 1. During the Sanger...

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