A) Restriction enzymes
B) Gel electrophoresis
C) Phage vectors
D) DNA cloning
E) Infection

A) They cut at regular intervals,every 4,000 base pairs.
B) They prefer to cut at DNA that has been methylated.
C) Restriction sites are palindromic sequences.
D) They only cut eukaryotic DNA.
E) An active restriction enzyme consists of one subunit.

A) before 1800.
B) between 1800 and 1900.
C) between 1900 and 1930.
D) between 1930 and 1950.
E) after 1950.