32P-end-labeled DNA fragment contains the AP-1–binding site…

32P-end-labeled DNA fragment contains the AP-1–binding site sequence. The DNA was mixed with Fos, FosC (a fragment of Fos), or Jun (all of which would form a homodimer), or with a mixture of Fos and Jun or a mixture of FosC and Jun (both of which would form the two types of homodimer and the heterodimer). Reactions were analyzed by polyacrylamide gel electrophoresis, then autoradiography.  The results are shown below.   This technique is called:

The presence of two copies of the X-chromosome in females bu…

The presence of two copies of the X-chromosome in females but only one in males poses a potential problem for regulation of gene expression: everything else being equal, the higher copy number of the X-linked genes can lead to an imbalanced overproduction of their products in females compared to males. Organisms have evolved different ______  mechanisms to solve this problem. In mammals, for example, the almost complete inactivation of one of the X chromosomes provides the solution to the dosage problem.