In the absence of growth factor, most animal cells will stop the cell cycle at a restriction point in what stage?
a. S phase
b. M phase
c. G2 phase
d. G1 phase
Ans: d. G1 phase
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Which of the following stages occurs immediately after the development of the zygote?
A. the development of the proembryo B. the heart stage when the cotyledon develops C. the development of globular stage D. the torpedo stage embryo forms
Water is important to the interactions of biological molecules because it ____.
A. is a good buffer B. destabilizes temperature C. is a poor solvent for polar and ionic substances D. has weak cohesive properties E. promotes hydrophilic interactions
Which of the following is notan example of a regulatory DNA site?
A. enhancer B. insulator C. repressor D. operator
In the treatment of ADA deficiency and SCID, which cell type was targeted for gene therapy?
A. Fibroblasts B. Embryonic stem cells C. Hematopoietic stem cells D. Lymphocytes E. Neutrophils