What is the total number of nucleotides in the recognition sequence for $EcoR\,I$?

Who discovered that restriction enzymes have the capability of cutting $DNA$ strands in a particular fashion,which left what has become known as 'sticky ends' on the strands?

Which of the following palindromic base sequences can be easily cut in the middle by some restriction enzymes?

Which statement is correct regarding the $DNA$ polymerase used in $PCR$?

$A$: Restriction enzymes belong to a larger class of enzymes called nucleases.
$R$: Each restriction enzyme recognizes a specific palindromic nucleotide sequence in the $DNA$.

Pathogenic bacteria gain resistance to antibiotics due to changes in their: