Consider the regulation of galactose metabolism through GAL4. Which of the following would result from a mutation that allowed GAL3 to bind to GAL80 in the absence of galactose?
A. GAL4 would no longer be able to bind to the DNA; thus, transcription of the genes involved in galactose metabolism would occur.
B. Transcription of the genes involved in galactose metabolism would occur both in the presence and in the absence of galactose.
C. GAL80 would no longer be able to stimulate transcription of the genes involved in galactose metabolism.
D. There would be no change in the regulation of galactose metabolism because GAL3 normally binds to GAL80 to cause a conformation change in GAL80.
E. GAL80 would be able to bind to GAL4, and transcription of the genes involved in galactose metabolism would be repressed.
Ans: B. Transcription of the genes involved in galactose metabolism would occur both in the presence and in the absence of galactose.
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In Drosophila, the hunchback gene encodes a protein (HB) that is required in the correct concentrations for proper segmentation of the embryo. In the zygote and embryo, the expression of hunchback is stimulated by high concentrations of Bicoid protein. You manipulate a Drosophila embryo to have high Bicoid concentrations throughout. Which of the following would occur?
A. The HB protein would not be produced at all. B. The HB protein would be produced throughout the entire embryo. C. Segmentation would not occur correctly. D. The HB protein would not be produced at all and segmentation would not occur correctly. E. The HB protein would be produced throughout the entire embryo and segmentation would not occur correctly.
What do binary fission and mitosis have in common?
a. They both occur in prokaryotic cells. b. They both occur in plant cells. c. They both require DNA replication before cell division. d. They have nothing in common.
Which of the following does NOT follow the base pairing rule?
A. A with T B. G with C C. U with D D. U with A
What would be the outcome, in genetic terms, of recombination between sister chromatids?
a. Genetic diversity is unaffected. b. Genetic diversity is decreased. c. Genetic diversity is increased. d. Nonhomologous chromatids are formed.