Table of Contents

• Model Citizens
• Sydney Brenner
• C. Elegans
• Other Model Organisms

Model Citizens

Model organisms are used in basic research to answer questions related to human disease and cellular activities. This includes cell growth, division, energy use, and communication. Model Organisms can be both complex and simple. This includes simple cell lines or complex as a mouse in a vivo system. The research can range from prokaryotic (bacteria) to single-cell eukaryotic (yeast), multicellular eukaryotic (fruit flies and worms), and mammalian models (mice and rats). It has shown that all living things share fundamental genetic material, allowing scientists to make comparisons between the model and a higher organism, such as human beings. However, due to the ethical barriers to doing research on human, model organisms help bridge the gap.

Sydney Brenner

Sydney Brenner is a Nobel peace prize winning researcher that used Caenorhabditis elegans (C. elegans) as an experimental model organism in the early 1960s. C. elegans are multicellular eukaryotic organisms that, like humans, are made up of specialized cells and complex systems such as neurons, muscle cells, a digestive and excretory system, and a reproductive system. Brenner went on to discover messenger RNS (mRNA) and defining the triple nature of the genetic code (codons). All this eventually led to his breakthrough in understanding programmed cell death (apoptosis).

C. Elegans

C. elegans respond to chemical, thermal, and mechanical stimuli, but no current scientific evidence indicates that C. elegans experience emotions, including pain. You have probably passed by C. Elegans multiple times in your life. However, you have never noticed it due to the worm’s microscopic nature at one millimeter. It is a free living nematode with an unsegmented cylindrical body with tapered ends, also known as a round worm. They live in temperate soil environments. Like humans, they have muscles, hypodermis, intestines, reproductive, excretory, and nervous systems. However, it has no circulatory or respiratory systems. It has 302 neurons, compared to humans 82 billion neurons. The reason it is such an easy organism to study is due to its clear nature. Researchers are able to visually see its neurons to look at the different connections between them. In just about a three and a half day reproductive cycle, the worm is able to produce three hundred organisms. Its entire genome has been sequenced! C. elegans eat bacteria. Specifically, C. elegans prefer a type of bacteria called Escherichia coli (abbreviated as E. coli). E. coli comes in many strains, but OP50 is the E. coli strain conventionally used as a bacterial food in the laboratory maintenance of C. elegans on agar plates. 

Other Model Organisms

Other examples of model organisms include mouse (mammalian genetics/disease), fruit fly (Drosophila) (genetics/development), zebrafish (Danio rerio) (vertebrate development/genetics), nematode worm (C. elegans) (neurobiology/aging), yeast (S. cerevisiae) (cell biology/genetics), and E. coli (bacteria) (molecular biology/genetics). Mice have been used for enabling breakthroughs in cancer drugs, understanding Alzheimer’s, developing vaccines for Ebola, gene therapy and treatments for diabetes and obesity. Fruit fly have been used to investigate Parkinson’s and ALS. Zebrafish have been used to investigate heart regeneration, Autism, TB, and regenerative medicine.