— 600

—u 450

300

— 150

A.    Martian DNA is made up of small chromosomes.

B.    Martian DNA is bound in nucleosomes that are spaced roughly 150bp apart

C.    Martian DNA is bound in nucleosome-like structures but spaced unevenly ranging from 150bp to 750bp.

D.    Micrococcal nuclease does not work very well on Martian DNA.

E.     All of the above

49.   Prolactin and glucocorticoids can both regulate the transcription of the casein gene. Although one is a protein and the other a steroid hormone, they are similar in that they: A. Are both nuclear receptor ligands.

B. Either directly or indirectly modify the binding of transcription factor homodimers to the casein promoter region to activate transcription.

C. Are both produced and act within the target cell.

D.   Do not circulate in the blood.

E.    Directly interact with RNA polymerase Il.

50.   DNAse I is used in footprinting to:

A.    Cleave all of the target DNA at every base-pair leaving only the DNA protected by the DNA binding protein.

B.    Bind to DNA to protect regions bound by the DNA binding protein.

C.    Cleave at specific sites along the DNA sequence to identify the underlying response element.

D.    Cleave essentially every DNA target molecule at a frequency of once per DNA molecule in regions unprotected by the DNA binding protein.

E.     Cleave the labelled end of the DNA target so that it does not cause background noise when the autoradiogram of the footprint is generated.