A molecular biologist treats a 600-kb length of linear DNA with HindIII restriction endonuclease. Following gel electrophoresis, the biologist observes that there is only one band on the gel corresponding with the migration distance of the 200-kb molecular weight marker. Assuming that no procedural errors were made, what can be concluded from these results?
A. There were no HindIII recognition sequences present in the original DNA.
B. Three HindIII recognition sequences were present in the original DNA.
C. One HindIII recognition sequence was present in the original DNA.
D. Two HindIII recognition sequences were present in the original DNA.
Answer: B
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For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate
and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work? A) There is no radioactive isotope of nitrogen. B) Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long. C) Although there are more nitrogens in a nucleotide, labeled phosphates actually have sixteen extra neutrons; therefore, they are more radioactive. D) Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
Rank the elements carbon, phosphorus, calcium, and iodine in order of decreasing number of energy shells/levels
A. CPCaI B. ICaPC C. IPCCa
During endocytosis, if a bacterial cell is not degraded and bacterial DNA is taken up by the eukaryotic cell, what may have occurred?
A. vertical evolution. B. horizontal gene transfer. C. vertical exon shuffling. D. chromosomal duplication and genomic exchange. E. both chromosomal duplication and vertical evolution.
Matching I. Choose the most appropriate answer for
each. 1. ___ colchicine 2. ___ deletion 3. ___ duplication 4. ___ inversion 5. ___ monosomy 6. ___ translocation 7. ___ triploidy 8. ___ trisomy A. 3n; generally sterile B. a chromosome segment is permanently transferred to a nonhomologous chromosome C. (2n – 1); a zygote deprived of a chromosome D. a repeat of a particular DNA sequence in the same chromosome or in nonhomologous ones E. (2n + 1); three chromosomes of the same kind are present in a set of chromosomes F. a piece of the chromosome is inadvertently left out during the repair process G. inhibits microtubule assembly; used in karyotyping H. a chromosome segment that has been cut out and rejoined at the same place, but backward