Bio 198 - Module 1 Exam Questions and 100% Correct Answers

Techniques for estimating the number of yeast cells in a culture... - Serial dilutions - Spectrophotometer - Compound microscopes - Estimating concentrations from a calibration curve What is an important single-cell organism? Yeast If you want to dilute yeast 1/10 - how much yeast and water would be in the dilution? What about 1/30? 1/10 = 1 ml yeast/ 9 ml water 1/30 = 1 ml yeast/ 29 ml water Spectrophotometer An instrument that measures the concentration of solutions by shining a beam of light at it - the more dissolved or suspended material the solution contains = the more the light will be blocked or absorbed by the solution When observing the yeast dilutions in a Spectrophotometer and there is more light absorbed, what does this tell you? There are more yeast cells present with more light absorbed Compound Microscope Relevant parts are the eyepiece, the fixed stage, several objectives with different magnifications, and a condenser that focuses the light shining through the specimen Dissecting Microscope An optical microscope variant designed for low magnification observation of a sample, typically using light reflected from the surface of an object rather than transmitted through it Absorbance Measures the amount of light absorbed (captured) by the dissolved or suspended material It is directly proportional to the amount of dissolved or suspended material in a solution EX: In the Yeast lab, we used the Spectrophotometer to measure the absorbance of the three dilutions of yeast What was the relationship between the measurements you made with the spectrophotometer and the cell counts you made using the microscope By using two different methods of extracting data, we were able to create a correlating graph that could then be used to for future analyses and measurements pertaining to the same specimen