You have isolated a piece of DNA that you believe contains an interesting gene. Using a mix of RNA polymerase and ribonucleotides, you perform in vitro transcription
However, even though all of your controls work, no mRNA is created from your DNA fragment. Working backward, you note that your DNA preparation removed approximately 250 base pairs from the 5' end of the gene. The most likely explanation is that during DNA preparation
A) the termination signal was removed.
B) the RNA polymerase became inactivated.
C) the 5' methyl guanosine cap was removed.
D) the promoter was removed.
E) None of these explains the negative results.
Answer: D
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Which is not a model for membrane structure?
A) Overton lipid coat B) Langmuir monolayer C) Gorter and Grendel bilayer D) Singer and Nicholson fluid mosaic E) Watson and Crick double helix
Which statement best explains why modern seedless vascular plants are confined largely to wet or humid environments?
a. They require external water for reproduction. b. They do not have true roots. c. They lack stomata. d. They have a dominant sporophyte generation. e. They do not have flowers or fruits.
Evolution can be defined as
A) one species diverging into two species. B) a change in the genetic makeup of a population over time. C) a change in the phenotype of an individual over his or her lifetime. D) a change in the genetic makeup of an organism over time. E) an individual changing into another species.
Some flowers have distinctive patterns that only reflect ultraviolet light and therefore are invisible to humans. Which statement about such markings is not correct?
A. The ultraviolet patterns repel birds and bats from the flowers. B. Carotenoid pigments are responsible for the ultraviolet patterns. C. Flowers with ultraviolet patterns usually appear yellow or orange to humans. D. The ultraviolet patterns often form a conspicuous central bull's eye or identify the best landing sites. E. The ultraviolet patterns are highly visible and attractive to bees.