Name: Chin Chang, Patrick Friedner, Kevin Reyes
Section: October 19, 2020
BIO 101 Lab 05: Osmosis and Diffusion in
, Red Blood Cells, and Potatoes
To submit, print this document, complete all lab activities and answer all questions. Scan lab pages 4-
6, and 10-12 using the free phone app AdobeScan, and upload your 1) Adobe Scan PDF, 2)
potato strips before soaking, and 3) photo of potato strips after soaking
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Please provide your instructor a copy of the Memorandum of Accommodation (MOA) from NVCC
Disability Support Services.
Review osmosis, diffusion, and cell membrane structure.
Observe plant and animal cells placed in solutions, hypotonic, isotonic, and hypertonic to the
cells and observe the effect of each of the solutions on the cells.
Interpret images of plant cells or red blood cells in different solutions.
Reinforce understanding of the experimental approach and data analysis.
Measure changes in potato cells to observe the effects of hypotonic and hypertonic and isotonic
solutions on plant cells.
Draw conclusions about osmosis across plant and animal cell membranes.
Cells and Cell Membrane structure.
Living cells are filled with an aqueous solution, the cytosol. Many small solutes or particles, are
dissolved in this watery cytosol, including ions, nutrients, waste, and enzymes.
Larger organelles (such
as mitochondria and chloroplasts) and large complexes of molecules (e.g. ribosomes) are also located in
this cytosol; organelles and complexes combine with the cytosol to form the cytoplasm of cells.
The exterior barrier of all cells is a cell membrane (plasma membrane). Because the cell membrane is
made of both phospholipids and proteins it is semi-permeable:
some molecules can easily pass through
the phospholipid bilayer, while other molecules cannot. Phospholipids have hydrophobic fatty acid tails
and hydrophilic phospho- heads. In the bilayer, the hydrophobic fatty acids are sandwiched between the
hydrophilic heads; one layer of polar heads lines the inside (cytosolic face) of the cell membrane and a
second layer of polar heads lines the outside (extracellular face) of the cell membrane or surface.
Transport through membranes.
Molecules that can easily pass through a cell membrane are small and nonpolar, such as gases: oxygen,
carbon dioxide, and nitrogen. Hydrophobic lipids (fats and steroids) can dissolve in the hydrophobic
fatty layer of the cell membrane and will diffuse into or out of a cell.
Some small molecules (e.g. sugars) and ions (sodium or chloride) can diffuse across a membrane if there
is a protein (transport protein or ion channel) These small solutes will move from areas of high
concentration to low concentration through a select protein that is part of the membrane.