Campbell Biology 11th Edition by Lisa Urry,Michael Cain,Steven Wasserman,Peter Minorsky,Jane Reece

Exercise 1

How Much New Cytoplasm and Plasma Membrane Are Made by a Growing Yeast Cell The unicellular yeast Saccharomyces cerevisiae divides by budding off a small new cell that then grows to full size. During its growth, the new cell synthesizes new cytoplasm, which increases its volume, and new plasma membrane, which increases its surface area. In this exercise, you will use a scale bar to determine the sizes of a mature parent yeast cell and a cell budding from it. You will then calculate the volume and surface area of each cell. You will use your calculations to determine how much cytoplasm and plasma membrane the new cell needs to synthesize to grow to full size.
How the Experiment Was Done Yeast cells were grown under conditions that promoted division by budding. The cells were then viewed with a differential interference contrast light microscope and photographed.
Data from the Experiment This light micrograph shows a budding yeast cell about to be released from the mature parent cell:
2. The shape of a yeast cell can be approximated by a sphere.
(a) Calculate the volume of each cell using the formula for the volume of a sphere:
Note that (the Greek letter pi) is a constant with an approximate value of 3.14, d stands for diameter, and r stands for radius, which is half the diameter. (b) How much new cytoplasm will the new cell have to synthesize as it matures To determine this, calculate the difference between the volume of the full-size cell and the volume of the new cell.