Indicate true (T) and false (F) statements below regarding gene control. Your answer would be a four-letter string composed of letters T and F only, e.g. TTFT.
( ) Development of multicellular organisms from a fertilized egg only rarely involves DNA rearrangements in specialized cells.
( ) A typical human cell expresses less than 1% of its approximately 30,000 genes at any given time.
( ) Genes that are expressed in all cell types usually vary in their level of expression in different cell types.
( ) Many differentiated plant cells can be fully de-differentiated and give rise to an entire plant.

The majority of transcription regulators make sequence-specific contacts with DNA in the major groove. In the two diagrams below, where are the contact surfaces that are exposed in the major groove?

Considering the diagrams below that show hydrogen-bond donors and acceptors as well as hydrophobic groups in four DNA base pairs, which of the following do you think is the most difficult to accomplish by DNA-binding proteins?