Tools Used to Study Genes

Instructor: Victoria Leo

Victoria teaches college, authors books, has a therapy practice and masters degrees in anthropology and psychology.

For thousands of years, humans have manipulated genes to domesticate plants and animals and create new species. In this lesson, we'll learn about various indirect ways to study genes and the most recent method of direct manipulation of genes.

An Ancient Scientific Path

Have you ever looked at your family tree and found yourself musing on how red hair or blue eyes seem to skip a generation throughout the tree - and then wondered why? Most of us have speculated about aspects of our ancestry from time to time, but did you know that this speculation follows an ancient scientific path? It's true! Creating detailed family trees is one of the oldest methods that scientists use to study genes.

The hundreds of discrete tools used to study genes include tools for both indirect studies of their effects and direct manipulation of DNA.

The Oldest Indirect Tools

The simplest and oldest form of indirect study, selective breeding, produced the first domesticated plants and animals thousands of years ago. The process continues among breeders and scientists today, with new breeds of dogs, cats, and even domesticated foxes. Modern scientists still learn a great deal from looking at directed breeding experiments in non-humans and from looking at human family trees, just as you do with your own family. Scientists first began to suspect that autism spectrum disorders were genetic diseases from studying the ancestors and extended family of severely affected individuals; such families always include less severely affected individuals. More recent genetic studies have confirmed the conclusion about the genetic nature of autism disorders. Many medical breakthroughs have stemmed from studies of identical twins.

Zeroing In on Special Individuals and Studying Non-Human Embryos

Scientists have hundreds of years of experience with the second category of tools for gene study, the extraordinary individual. From developmental disorders like microcephaly (part of the brain missing) through individuals born without limbs and with other biological differences, scientists still start much of their medical detective work with individuals who are different in some way. Medical researchers are intensively studying extraordinary individuals who are repeatedly exposed to the HIV virus as sex workers, but whose immune systems are adept at identifying and neutralizing the invading viruses. Detailed analysis of these individuals' genes is helping researchers get closer to an HIV vaccine.

The third tool in the indirect study of genes is making minute changes in the cells of a non-human organism's earliest embryonic development to see what changes occur as the organism develops through the fetal stage and then birth. Scientists have also used chemicals to ''knock out'' specific genes during embryonic life and traced the changes that occur in the organism's future development.

Direct Manipulation of Genes

Now we are ready to discuss a tool that has taken the world of biology by storm - direct editing of an organism's genome by nucleases and CRISPR. A nuclease cuts out sections of DNA or RNA, and even individual genes, in concert with clustered regularly interspaced short palindromic repeats (CRISPRs, pronounced ''crispers''). The first nuclease, discovered barely a decade ago, was Cas9, shortly followed by Cpf1. The American Association for the Advancement of Science was so impressed with the growing avalanche of research - and research areas - that CRISPR/Cas9 was revolutionizing that they named it the breakthrough of the year (from all areas of science) in 2015. CRISPR tools are being used to create new disease-resistant, and drought- and flood-tolerant, strains of food crops, and new species and breeds of farm animals. Medical researchers are also poised to use CRISPR to study human genes more intensely.

The Benefits and Dangers of Manipulating the Human Genome

Anyone who has suffered along with a loved one with a genetic disease finds it very easy to be excited about the prospect of eliminating diseases that prevent people from enjoying a normal human lifespan, or which impose significant suffering. Using CRISPR techniques to eliminate the one-gene genetic diseases is expected to be possible by 2026, according to scientists using the technique on non-human genomes. Diseases with more complex, multi-gene causes will require more research, but will certainly be available before babies born in 2016 are ready to start their own families. Diseases like cardiovascular disease and diabetes may become rarer as the genes that increase susceptibility to them are eliminated from the human genome.

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