This micrograph was taken at 400X total magnifcation on a brightfield microscope. The subject is Candida albicans cells grown in broth culture at 30 degrees Celsius. The cells were heat-fixed to a slide and Gram stained prior to visualization.Image credit: Emily Fox

This lesson is the second of two that explore cellular respiration and population growth in yeasts. In the first lesson, students set up a simple way to indirectly observe and quantify the amount of respiration occurring in yeast-molasses cultures. Based on questions that arose during the first lesson and its associated activity, in this lesson students work in small groups to design experiments that will determine how environmental factors affect yeast population growth.

In this activity, students act as environmental engineers involved with the clean up of a toxic spill. Using bioremediation as the process, students select which bacteria they will use to eat up the pollutant spilled. Students learn how engineers use bioremediation to make organism degrade harmful chemicals. Engineers must make sure bacteria have everything they need to live and degrade contaminants for bioremediation to happen. Students learn about the needs of living things by setting up an experiment with yeast. The scientific method is reinforced as students must design the experiment themselves making sure they include a control and complete parts of a formal lab report.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Scientists have created a “super” sourdough that could help breadmakers and microbiome researchers alike answer long-standing questions, including how a sourdough’s microbial makeup might make it more stable than others. The team created their synthetic sourdough by pulling bacteria and yeast from 8 spontaneously formed sourdoughs from around the world. These microbes fulfilled two criteria: 1) they occurred in 4 of the 8 spontaneous sourdoughs, and 2) they harbored at least 20 key genes associated with metabolic pathways critical to maintaining sourdough quality, including the fermentation and breakdown of different sugars. Seven species (5 bacteria, 2 yeasts) met these criteria, forming a global sourdough labeled “SDG.” Scientists compared SDG with a synthetic sourdough (SMC-SD43) modeled after one of the original 8 spontaneous sourdoughs..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This rich learning object is used to introduce yeast cytology to students taking Module D24BS3 Brewery Yeast Management as part of the MSc in Brewing Science. The virtual cell permits the students to understand structure and function of yeast organelles.

In this activity, learners make a yeast-air balloon to get a better idea of what yeast can do. Learners discover that the purpose of leaveners like yeast is to produce the gas that makes bread rise. Learners discover that as yeast feeds on sugar, it produces carbon dioxide which slowly fills the balloon.

Students set up a simple way to indirectly observe and quantify the amount of respiration occurring in yeast-molasses cultures. Each student adds a small amount of baking yeast to a test tube filled with diluted molasses. A second, smaller test tube is then placed upside-down inside the solution. As the yeast cells respire, the carbon dioxide they produce is trapped inside the inverted test tube, producing a growing bubble of gas that is easily observed and measured. Students are presented with the procedure for designing an effective experiment; they learn to think critically about experimental results and indirect observations of experimental events.

This module provides an introduction to plasmids, small circular DNA molecules that replicate independently of the host cell DNA. The module focuses on yeast overexpression plasmids, which have replication origins and selectable markers that allow them to be propagated in either bacteria or yeast. The plasmids also contain promoters that control expression of a cloned gene in Saccharomyces cerevisiae. In this module, students will:understand the various features that have been engineered into plasmids for experimental purposeslearn how the physical properties of plasmids are used in their purificationisolate plasmids from E. coli estimate plasmid concentration and purity using ultraviolet spectroscopyThis module is part of a semester-long introductory labortory course, Investigations in Molecular Cell Biology, at Boston College

In this module, students use a simple method to transform the budding yeast, Saccharomyces cerevisiae, with yeast expression plasmids containing the GAL1 promoter. At the end of this module, students will be able to:explain the processes of transformation and complmentation at the molecular leveldesign a selection strategy to isolate transformed strains explain how plasmid-encoded genes can complement gene deficienciesuse replica plating on selective media to identify transformed strains expressing plasmid-encoded genesThis module is part of a semester-long introductory laboratory course, Investigations in Molecular Cell Biology, at Boston College. 

In this module, students design and implement a strategy to identify yeast deletion strains by colony PCR. At the end of this module, students should be able to:design oligonucleotide primers to amplify specific DNA sequences with PCRexplain how changes to the annealing and extension times affect the production of PCR productsuse PCR to distinguish mutant yeast strains with different genotypesThis module is part of a semester-long introductory lab course, Investigations in Molecular Cell BIology, at Boston College.

This module introduces students to sterile culture techniques using Saccharomyces cerevisiae. Studentslearn the relationships between species and strainsisolate individual colonies from liquid cultures on streak platesprepare serial dilutions of liquid cultures for spot plates, which are used to estimate the concentration of viable cells in the culturesestimate cell densities in liquid cultures using the spectrophotometerThis module is part of a semester-long introductory lab course, Investigations in Molecular Cell Biology, at Boston College.