A murder has occurred, and you are asked to help solve it. The police bring you a sample from the crime scene of what they believe is the killer’s DNA and ask you for a chemical analysis. Your study of this sample reveals the presence of adenine, thymine, ribose, and uracil, leading you to conclude that the sample is
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Solution
The available evidence indicates that both DNA and RNA are present in the sample.The logic here is that thymine is unique to DNA, and both ribose and uracil are found only in RNA.With this evidence,however, you can say nothing about the types of RNA present in the sample,or whether the sample is actually from the killer.
Telomerase is an enzyme which is a
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Solution
Telomerase is a ribonucleoprotein which synthesize the rich strand of telomers in DNA. Telomerase is an enzyme that adds specific DNA sequence repeats (“TTAGGG” in all vertebrates) to the 3'end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes.
A short sequence of bases on one strand of DNA is AGTCTACCGATAGT. If this sequence serves as a template for the formation of a new strand of DNA, what will be the corresponding base sequence in the new strand?
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Solution
The complementary base will pair with each base on the template to form the specific sequence shown.
Consider Griffith’s experiments on transformation in Streptococcus pneumoniae. Now imagine that you are extending these experiments by injecting a mixture of heat-killed strain R bacteria and live strain S bacteria into a mouse.The result will be that the mouse will _______, and you will find live strain _______ bacteria in its blood.
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Solution
Since strain R bacteria do not harm the mouse, this experiment is the equivalent of injecting the virulent strain S only. Thus the mouse will die, and you will find living strain S bacteria in its blood.
The primary reason DNA was first thought to be a poor candidate for the hereditary material was that
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Solution
Since the building blocks of DNA were thought to be structurally simple and few number, biologists prior to the 1940s thought that only proteins could have the necessary complexity and diversity to be the hereditary material.
Operon is
Which of the following parts of a DNA molecule are held together by hydrogen bonds?
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Solution
Hydrogen bonds connect the bases on opposite strands of the DNA molecule, which is the reason that the helix can be unwound and separated relatively easily. All other bonds in file molecule are covalent.
The primary purpose of Griffith’s experiments on the Streptococcus pneumoniae bacterium was to
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Solution
Griffith was a physician trying to find away to effectively treat or cure pneumonia. Nothing much was known about the structure or function of DNA at the time he did his work.
Which of the following would you not expect to find in prokaryotic DNA?
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Solution
Histone proteins are used to coil the large amount of DNA found in eukaryotes so that it can be packaged more efficiently within the cell. Prokaryotes do not face this problem because they have much less DNA.
Chromatin structure must be altered in order for gene expression to occur because
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Solution
Nucleosomes condense the DNA. Heterochromatin is transcriptionally inactive, while euchromatin is transcriptionally active.