. Which is used to cut DNA molecules at specific points? a restriction enzyme recombinant DNA PCR analysis gel electrophoresis

## Step 1<br />The question asks which tool is used to cut DNA molecules at specific points. The options provided are: a restriction enzyme, recombinant DNA, PCR analysis, and gel electrophoresis.<br /><br />## Step 2<br />A restriction enzyme, also known as a restriction endonuclease, is a protein that cuts DNA at specific points. These enzymes recognize specific DNA sequences and cut the DNA at those points. This property is used in genetic engineering to cut DNA into smaller pieces for further analysis or manipulation.<br /><br />## Step 3<br />Recombinant DNA is a form of DNA that does not occur naturally but is created by combining DNA sequences that would not normally occur together. It is not a tool used to cut DNA.<br /><br />## Step 4<br />PCR analysis, or Polymerase Chain Reaction, is a method used to amplify a specific DNA sequence, creating millions to billions of copies. It does not cut DNA.<br /><br />## Step 5<br />Gel electrophoresis is a technique used to separate DNA fragments based on their size. It does not cut DNA but separates it after it has been cut.