Biotechnology review

Key terms

Biotechnology

DNA technologies

Examples of DNA technologies

• Polymerase chain reaction (PCR) is a widely used DNA manipulation technique, one with applications in almost every area of modern biology. PCR reactions produce many copies of a target DNA sequence starting from a piece of template DNA. This technique can be used to make many copies of DNA that is present in trace amounts (e.g., in a droplet of blood at a crime scene).
• Gel electrophoresis is a technique used to visualize (directly see) DNA fragments. For instance, researchers can analyze the results of a PCR reaction by examining the DNA fragments it produces on a gel.
  Gel electrophoresis separates DNA fragments based on their size, and the fragments are stained with a dye so the researcher can see them. They can then be used as a way to compare how similar DNA samples are to one another.

  DNA fragments migrate through the gel from the negative to the positive electrode.

  After the gel has run, the fragments are separated by size, with the smallest ones near the bottom (positive electrode) and the largest ones near the top (negative electrode).

• In DNA cloning, researchers make many copies of a DNA fragment of interest, such as a gene. In many cases, DNA cloning involves inserting a target gene into a circular DNA molecule called a plasmid. The insertion is done using enzymes that “cut and paste” DNA, and it produces a molecule of recombinant DNA.
  The plasmid can be replicated in bacteria, making many copies of the gene of interest. In some cases, the gene is also expressed in the bacteria, making a protein (such as the insulin used by diabetics).

  Insertion of a gene into a plasmid.

• DNA sequencing involves determining the sequence of nucleotide bases (As, Ts, Cs, and Gs) in a DNA molecule. In some cases, just one piece of DNA is sequenced at a time, while in other cases, a large collection of DNA fragments (such as those from an entire genome) may be sequenced as a group.

Bioethics

Examples of bioethical considerations

• Privacy and non-discrimination: Should your health insurance company be able to charge you more if you have a gene variant that makes you likely to develop a disease? How would you feel if your school or employer had access to your genome?
• Safety, health effects, or ecological impacts of biotechnologies: For example, some genetically engineered crops can make their own insecticide, reducing the need for chemical spraying. However, this raises concerns about plants escaping into the wild or interbreeding with local populations, potentially causing unintended ecological consequences.
• Difficult decision-making for individuals: For example, a couple may learn via prenatal testing that their fetus has a genetic disorder. Similarly, a person who has her genome sequenced for the sake of curiosity may learn that she is going to develop an incurable, late-onset genetic disease, such as Huntington's.

Common mistakes and misconceptions

• Science alone cannot determine how these biotechnology should or shouldn’t be used. Biotechnology is not inherently unsafe, untested, or unpredictable, and scientific research and development can make new information, techniques, and knowledge available. However, it's important for all members of society to have their voices heard in the conversation about biotechnology inventions and products that can affect our everyday lives.
• Clones are not formed instantly. A common belief is that if a clone is created, it would appear at the same age as the original. For example, if an embryo of an organism is cloned, it must have time to develop into a full-grown individual, much like any other embryo. Because the clone grows and has its own experiences, it may not act anything like the original, even if it is a genetic copy.

  Image of the taxidermied remains of Dolly the cloned sheep, in the National Museums of Scotland, Edinburgh.

  In addition, not all clones are created artificially. Clones are simply identical genetic copies, and many organisms naturally reproduce through cloning. For example, bacteria reproduce by binary fission, during which they copy their DNA and divide into two.