Saccharomyces cerevisiae is a species of yeast that is an extremely valuable model organism. Importantly, S. cerevisiae is a unicellular eukaryote that undergoes many of the same biological processes as humans. This video provides an introduction to the yeast cell cycle, and explains how S. cerevisiae reproduces both asexually and sexually Yeast reproduce asexually through a process known as budding. In contrast, yeast sometimes participate in sexual reproduction, which is important because it introduces genetic variation to a population. During environmentally stressful conditions, S. cerevisiae will undergo meiosis and form haploid spores that are released when environmental conditions improve. During sexual reproduction, these haploid spores fuse, ultimately forming a diploid zygote. In the lab, yeast can be genetically manipulated to further understand the genetic regulation of the cell cycle, reproduction, aging, and development. Therefore, scientists study the reproduction of yeast to gain insight into processes that are important in human biology.