Homework Help: Science: Biology: DNA Manipulation

DNA Manipulation can be divided into four different categories:

• cutting
• separating
• reading
• splicing

Cutting DNA

DNA can be cut precisely by using proteins known as restriction enzymes. There are over one-hundred different restriction enzymes we know of, and each one cuts a different area of DNA. Therefore, when a scientist wants to cut DNA, he or she can mix the appropriate enzyme with DNA, and a chemical reaction will occur. The result is cut DNA.

Separating DNA

After DNA is cut, it's not separated yet. To separate DNA, scientists can use a process known as electrophoresis. In electrophoresis, DNA is placed in a special gel. Parts of the gel are positively charged, and DNA is negatively charged. Therefore, DNA fragments move toward specific areas of the gel. Different fragments move at different speeds toward the positive charges, enabling scientists to separate DNA.

Reading DNA

To read DNA, scientists first place it in a test tube full of DNA polymerase. A complementary strand is created, and the complementary strand is separated using electrophoresis. The result is the base sequence of the original strand. Today, reading DNA is so common that computers complete sequencing without human aid.

Splicing DNA

To splice means to join. In other words, scientists can join to fragments of DNA just as they can separate them. When some restriction enzymes cut DNA, they leave a single stranded region on each side of the cut DNA. Therefore, if two fragments of DNA are cut by the same enzyme the singe-stranded regions can put the fragments back together. Additional enzymes can then be used to make the splice permanent.

Homework Help: Science: Biology

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