How did Seymour Benzer use deletion mapping to construct fine-scale maps of the rII region of the T4 bacteriophage genome?
What will be an ideal response?
He used deletion mutants, which, unlike point mutants, have lost a segment of DNA and cannot revert to a wild-type state. He crossed unknown point mutants with standard (known) deletion mutants for different segments of the rII region to determine which crosses could result in wild-type recombinant phage. Those that could not must have used point mutants with a mutation in the region of the deletion. This could be repeated in crosses between the point mutant and smaller secondary reference deletion mutants until the point mutation was localized to within a very small segment of the rII region.
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How do cells "interact" with the extracellular matrix?
A. through cadherins B. through integrins C. through gap junctions D. through tight junctions
Which of the following statements is correct?
a. Intracellular digestion is seen in mammals. b. Intracellular digestion never involves choanocytes. c. Extracellular digestion must involve choanocytes. d. Extracellular digestion may take place in a tube contained inside the body. e. Most animals experience both intracellular and extracellular digestion.
If you found a species of plant consisting of widely separated small populations, what might you expect?
A. low genetic diversity B. bottleneck effects C. increased likelihood of extinction D. genetic isolation among subpopulations E. All of the answer choices are correct.
How many molecules of ATP are needed to reduce one molecule of carbon dioxide to carbohydrate by oxygenic phototrophs during the dark reactions of photosynthesis?
A. 3 B. 2 C. 10-12 D. 4