b
In his work with pneumonia-causing bacteria and mice, Griffith found out that
a. the protein coat from pathogenic cells was able to transform nonpathogenic cells.
b. heat-killed pathogenic cells caused pneumonia.
c. some substances from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic
d. the polysaccharide coat of bacteria caused pneumonia.
What is the basis for the differences in how the leading and lagging strands of DNA molecules are synthesized?
a. The origins of replication occur only at the 5'end.
b. Helicases and single-strand binding proteins work at the 5' end.
c. DNA polymerase can join new nucleotides only to the 3'end of a pre-existing strand.
d. DNA ligase works only in the 3'->5' direction.