A model organism is a species that has been widely studied, usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages. Model organisms are non-human species that are used in the laboratory to help scientists understand biological processes. They are usually organisms that are easy to maintain and breed in a laboratory setting. For example,  they may have particularly robust embryos that are easily studied and manipulated in the lab, this is useful for scientists studying development, or they may occupy a pivotal position in the evolutionary tree, which is useful for scientists studying evolution. In researching human disease, model organisms allow for a better understanding of the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency to humans, to react to disease or its treatment in a way that resembles human physiology as needed. Although biological activity in a model organism does not ensure an effect in humans, many drugs, treatments and cures for human diseases are developed in part with the guidance of animal models.

Saccharomyces cerevisiae- Saccharomyces cerevisiae is a species of yeast. It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology. It is the microorganism behind the most common type of fermentation. S. cerevisiae has developed as a model organism because it scores favourably on a number of these criteria. S. cerevisiae has been highly studied as a model organism to better understand ageing for more than five decades and has contributed to the identification of more mammalian genes affecting ageing than any other model organism. Some of the topics studied using yeast are calorie restriction, as well as in genes and cellular pathways involved in senescence