Membranes and Cellular
Transport
WARM-UP:
Write a story about
organelles, in 7 words.
Adventure vesicle roamed the membranes. Golgi waved.
Animal cells vs. Plant cells
Objective:
Describe the function and components of biological
membranes
Relate membrane function to HOMEOSTASIS.
Oil and Water don’t mix!
Water Soluble
Not Water Soluble
Membrane lipids
Detergent micelles lift and solubilize dirt
Which biomolecule is the
building block of membranes?
Structure of the cell membrane
Phospholipids alone don’t
make up a living membrane
Anatomy of a red blood cell
What happens to
red blood cells in
capillaries (tiny
blood vessels?)
http://www.ifs.tohoku.ac.jp/sme/activity/1995-1999.html
Predict: What are the
possibilities?
What happens when you put a red blood cell in water?
What happens when you put a red blood cell in salt solution?
Diffusion, Osmosis, Cellular
Transport
Define the following:
1. Hypotonic
2. Hypertonic
3. Isotonic
Relative solute concentrations
outside and inside cells
Outside isotonic
isotonicSolute
Solute
Outside hypertonic
Cytosol
Cytosol
Water
Outside hypotonic
Water 
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction o
A biologist working with cultured cells
uses distilled water instead of serum.
When he looks for the cells he sees only
debris. What happened to his cells?
What happens when we expose
onion cells to high salt?
Procedure:
Place a thin sliver of moist onion
tissue (red colored) onto a glass
slide.
Put a drop of water on the slide
and drop a cover slip. Record
your observations.
Now touch the edge of the slide
with a dropper filled with salt
solution. Allow salty water to
draw across the cover slip.
Record the time and record your
observations.
Frog Oocytes expressing putative transport protein
Control
CHIP28 protein
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Oocytes placed in Hypotonic
medium
Oocyte rupturing
Oocyte
3–5 minutes
Control
CHIP28
Control
CHIP28
Courtesy Dr. Peter Agre. From GM Preston, TP Carroll, WP Guggino, P Agre (1992), “Appearance of
water channels in Xenopus oocytes expressing red cell CHIP28 protein,” Science, 256(5055):385–7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Aquaporin: protein channel that allows
water to enter cells at a faster rate than
diffusion
Facilitated
Diffusion
Brain teaser:
Emma has stomach aches
and persistent diarrhea. Her
favorite drink is apple juice.
Emma’s pediatrician wants
her to cut back. What is
going on?