Intro to biotechnology

Key points:

• Biotechnology is the use of an organism, or a component of an organism or other biological system, to make a product or process.
• Many forms of modern biotechnology rely on DNA technology.
• DNA technology is the sequencing, analysis, and cutting-and-pasting of DNA.
• Common forms of DNA technology include DNA sequencing, polymerase chain reaction, DNA cloning, and gel electrophoresis.
• Biotechnology inventions can raise new practical concerns and ethical questions that must be addressed with informed input from all of society.

Introduction

What is biotechnology?

• Beer brewing. In beer brewing, tiny fungi (yeasts) are introduced into a solution of malted barley sugar, which they busily metabolize through a process called fermentation. The by-product of the fermentation is the alcohol that’s found in beer. Here, we see an organism – the yeast – being used to make a product for human consumption.
• Penicillin. The antibiotic penicillin is generated by certain molds. To make small amounts of penicillin for use in early clinical trials, researchers had to grow up to $500$500 liters of “mold juice” a week$^1$start superscript, 1, end superscript. The process has since been improved for industrial production, with use of higher-producing mold strains and better culture conditions to increase yield$^2$squared. Here, we see an organism (mold) being used to make a product for human use – in this case, an antibiotic to treat bacterial infections.

• Gene therapy. Gene therapy is an emerging technique used to treat genetic disorders that are caused by a nonfunctional gene. It works by delivering the “missing” gene’s DNA to the cells of the body. For instance, in the genetic disorder cystic fibrosis, people lack function of a gene for a chloride channel produced in the lungs. In a recent gene therapy clinical trial, a copy of the functional gene was inserted into a circular DNA molecule called a plasmid and delivered to patients’ lung cells in spheres of membrane (in the form of a spray)$^3$cubed.
  In this example, biological components from different sources (a gene from humans, a plasmid originally from bacteria) were combined to make a new product that helped preserve lung function in cystic fibrosis patients.

What is DNA technology?

Examples of DNA technologies

• DNA cloning. In DNA cloning, researchers “clone” – 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 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.
• Polymerase chain reaction (PCR). Polymerase chain reaction is another 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. 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.
  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).

  Based on similar diagram in Reece et al.$^5$start superscript, 5, end superscript
• DNA sequencing. 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.

  [What is a genome?]

Biotechnology raises new ethical questions

• Some of these relate to privacy and non-discrimination. For instance 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?
• Other questions relate to the safety, health effects, or ecological impacts of biotechnologies. For example, crops genetically engineered to make their own insecticide reduce the need for chemical spraying, but also raise concerns about plants escaping into the wild or interbreeding with local populations (potentially causing unintended ecological consequences).
• Biotechnology may provide knowledge that creates hard dilemmas 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.

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