A scientist uses radioactive isotopes to label a double-stranded molecule 4 points
of DNA. Then the DNA undergoes replication in a non-radioactive
medium. Where are the two original radioactive strands of DNA?
O
a. Both strands are intact, and both are part of the same molecule of DNA.
b. Both strands are intact, and each is part of a different molecule of DNA.
c. One strand is intact, while the other strand is broken apart and distributed among
the new DNA molecules.
d. Both strands are broken apart, and their pieces are distributed among the new DNA
molecules.

Mr. j, age 42, is a construction worker in las vegas. he recently noticed that a mole on his face seemed to be getting larger and darker. at first he did not worry because he was in the sun a lot and assumed the change may have been caused by sunburn. after a month, not only was the mole larger and darker, but it appeared to be “bumpy.” his doctor diagnosed a malignant melanoma skin cancer following biopsy of the nevus. mr. j reports pain in his right shin that does not go away when he puts his feet up or sleeps. discussion questions 1. relate mr. j’s skin changes to the warning signs for malignant melanoma. (see malignant melanoma.) 2. discuss the normal progression of this malignancy. what is the significance of the bone pain that mr. j is experiencing? (see malignant melanoma.) 3. discuss the treatment available for this patient and the prognosis for recovery. (see malignant melanoma.)