Look at Chargaff’s Data for humans. Calculate the ratio of A to T and G to C? Show your work
A to T ratio: __
What does this ratio tell you?
G to C ratio: __
What does this ratio tell you?

Quickly review the data for the other organisms in the table. Do the ratio findings only occur for human DNA? Explain.

If you were Chargaff, what conclusion would you draw based on the data comparison?

Chargaff also compared the base pairing ratios of different organisms. Compare the human DNA base composition to the other organisms. Do any of the other organisms have the same percentage distribution as human DNA? Explain.

Which organism has the closest base composition to the human’s? ______________

Which organism’s base composition is furthest from the human’s? _______________

If you were Chargaff, what conclusion would you draw based on this data comparison?