Unit 4: The Cell and Membrane Transport
Key Questions: Use these questions to check your understanding of the material in this unit.
1. Compartmentalization is an important term that describes the structure and general
functionality of eukaryotic cells. Explain what is meant by this statement and what the
advantage of compartmentalization is for eukaryotic cells that prokaryotic lack.
2. The cell membrane has to be dynamic and responsive to external conditions. What model of
the cell membrane describes this property of cell membranes? Describe this model, how it
illustrates the dynamic quality of membranes, and why it is necessary for the membrane to be
so adaptable to external conditions.
3. Why can you smell a bakery before you arrive at it while walking down the street? Explain in
detail.
4. If equilibrium is reached, will the molecules involved stop moving? Why/why not? Explain.
5. A cell has three options for bringing things across its cell membrane. Identify and discuss
which option a cell would use for bringing across each of the following: Ca 2+, water, and
starch. (Be sure to include why this method is used over another)
6. Describe the key concepts you experienced in the Gummi Bear Lab and the Diffusion Lab.
Explain how your procedures enabled you to collect data to support these key concepts?
Applied Questions: The purpose of these questions is to provide an opportunity for you to
apply your understanding of the concepts in this unit in new ways. Keep in mind, the answers
should involve several concepts and include as many details and evidence as relevant.
1. Lipoproteins are relatively large, spherical clumps of protein and lipid molecules that circulate
in the blood of mammals. They are like suitcases that move cholesterol, fatty acid remnants,
triglycerides and phospholipids from one place to another in the body. Given what you know
about the insolubility of lipids in water, which of the four kinds of lipids would you predict to
be on the outside of the lipoprotein clump, bathed in the fluid (water-based) portion of the
blood?
2. Water moves into a paramecium, a single-celled aquatic protist. If unchecked, the influx
would bloat the cell and burst it, but contractile vacuoles expel excess water. This works by
water entering into the vacuoles (a “bubble” within the organism) until the vacuoles are full.
Once full, the vacuole contracts, squirting the excess water out of the organism. Is this
organism hyper, hypo or isotonic relative to the water the organism floats in? Are the
organism’s vacuoles hyper, hypo or isotonic relative to the organism? Are the vacuoles hyper,
hypo or isotonic relative to the water the organism floats in? Explain your answer.
Reading and Other Resources:
Campbell, Essential Biology with Physiology
Chapter 4: Tour of the Cell – Page 59-70
Chapter 5: The Working Cell – Page 76-77, 83-85
Activities and Labs
● Cell Building Activity
● Gummy Bear Lab
● Diffusion Lab
Chapter 4: A Tour of The Cell
● Organelle
● Cytoplasm
● Cytosol
● Plasma membrane
● Phospholipid bilayer
● Fluid Mosaic
Chapter 5: The Working Cell
● Passive transport
● Diffusion
● Concentration
gradient
● Facilitated diffusion
● Osmosis
Nucleus
Nuclear envelope
Ribosome
Rough endoplasmic
reticulum
● Golgi apparatus
●
●
●
●
●
●
●
●
●
●
Solute
Solvent
Solution
Hypertonic
Hypotonic
Isotonic
● Vesicle
● Lysosome
● Mitochondria
●
●
●
●
Active transport
Exocytosis
Endocytosis
Dialysis tubing
Useful Resources and Links
If you don’t fully understand eukaryotic cell organelles:
● Bozeman Science: Cell Organelles - https://youtu.be/aczbMlSMr8U
● Eukaryopolis: The City of Animal Cells-Crash Course Biology #4 - https://youtu.be/cj8dDTHGJBY
● Biology: Cell Structure - https://youtu.be/URUJD5NEXC8
If you don’t fully understand membrane structure and function:
● Fluid Mosaic Model - https://youtu.be/Qqsf_UJcfBc
● Cell Membranes (some info not required to know, but great explanations) http://www.johnkyrk.com/cellmembrane.html
● *Cell Membranes - http://learn.genetics.utah.edu/content/cells/membranes/
● Biomembranes I: Membrane Structure and Transport http://www.phschool.com/science/biology_place/biocoach/biomembrane1/intro.html
● Cell Membranes (some info not required to know, but great explanations) http://www.johnkyrk.com/cellmembrane.html
● Membrane Transport Tutorial http://www.wiley.com/college/pratt/0471393878/student/animations/membrane_transpo
rt/index.html
If you don’t fully understand entropy and passive transport:
● Crash course: Entropy (https://youtu.be/ZsY4WcQOrfk)
● Diffusion Animation http://esminfo.prenhall.com/science/BiologyArchive/lectureanimations/closerlook/diffusio
n.html
● Diffusion Tutorial http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__
how_diffusion_works.html
● *Bozeman Science: Membrane Transport - https://youtu.be/RPAZvs4hvGA (ignore active
transport)
● Crash Course: In Da Club – Membrane Transport -https://youtu.be/dPKvHrD1eS4
If you don’t fully understand active transport:
● Exocytosis and endocytosis https://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/fre
e/0072437316/120068/bio02.swf::Endocytosis%20and%20Exocytosis
● Active Transport (sodium/potassium pump) - https://youtu.be/yz7EHJFDEJs
● *Bozeman Science: Membrane Transport - https://youtu.be/RPAZvs4hvGA (ignore active
transport)