Which of the following is notan example of a regulatory DNA site?
A. enhancer
B. insulator
C. repressor
D. operator
C
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What must be true of any organ described as vestigial?
A) It must be analogous to some feature in an ancestor. B) It must be homologous to some feature in an ancestor. C) It must be both homologous and analogous to some feature in an ancestor. D) It need be neither homologous nor analogous to some feature in an ancestor.
In science, experiments are widely used. Are experiments better than observational studies? Discuss the merits and shortcomings of both types of studies.
What will be an ideal response?
Baculovirus genomes are 133.9 kb long and encode over 150 genes. This suggests that
A. their protein structures are very complex. B. their protein coats consist of very few types of protein subunits. C. their genetic material is RNA. D. their genetic material is DNA. E. they have a small host range.
Tamoxifen is a drug that is used to treat breast cancer. It inhibits the activities of the estrogen receptor in breast epithelial cells, which are the cells that are relevant to breast cancer. One of the concerns that scientists had during the development of Tamoxifen as a therapy for breast cancer was that other cell types require estrogen signaling for their function. For example, it is known
that cells in bone tissue require estrogen signaling. As a result, there was a concern that use of Tamoxifen would lead to bone loss in patients. In reality, however, researchers were surprised to find that Tamoxifen actually led to an increase in bone density in breast cancer patients. At the same time, Tamoxifen did inhibit the activity of the estrogen receptor in breast epithelial cells in these patients. What is the best explanation for this finding? A. Tamoxifen binds different parts of the estrogen receptor in different tissues. B. The estrogen receptor is bound to different coactivators in different tissues. C. Tamoxifen can only enter certain cell types. D. Bone cells make use of a different type of estrogen receptor that does not bind to Tamoxifen.