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BIO301: Cell Biology

Unit 2: The Cell Membrane   Organisms must be able to maintain homeostasis, or a constant internal environment, in order to survive. Cells achieve homeostasis by creating a barrier to the outside world—a cell membrane—that enables them to protect their internal environment from external forces. In fact, cells die when the cell membrane’s integrity is destroyed or compromised. In this unit, you will learn about the membrane and its properties. You will discover that the cell membrane serves as much more than just a wall—it also transports nutrients, exports waste, carries signals, and much more.

Unit 2 Time Advisory
Completing this unit will take you approximately 13 hours.

☐    Subunits 2.1: 3.5 hours

☐    Subunits 2.2: 0.5 hours

☐    Subunit 2.3: 2 hours

☐    Subunit 2.4: 2.5 hours

☐    Subunit 2.5: 1 hour

☐    Subunit 2.6: 2.5 hours

☐    Assessment: 1 hour

Unit2 Learning Outcomes
Upon completion of this unit, you will be able to
- identify the components of membranes; - describe how these components affect membrane properties; - identify types of membrane transport (specific pumps and channels); and - describe the role of various molecules and ions (e.g. sodium, calcium) in this transport.

2.1 Membrane Components   - Reading: National Center for Biotechnology Information’s Bookshelf: Sinauer Associates: Professor Geoffrey Cooper’s The Cell, A Molecular Approach, 2e: “Cell Membranes” Link: National Center for Biotechnology Information’s Bookshelf: Sinauer Associates: Professor Geoffrey Cooper’s The Cell, A Molecular Approach, 2e: Cell Membranes (HTML)
 
Instructions: Read the introduction and the subsections “Membrane Lipids” and “Membrane Proteins,” along with all associated figures and tables (Figs. 2.45–2.48 and Table 2.3). These will cover the material in 2.1–2.3.

 Reading this text and taking notes should take approximately 1
hour.  
    
 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Lecture: University of California, Berkeley: Professor Randy Schekman’s “Membrane Structures: Lipids” Link: University of California, Berkeley: Professor Randy Schekman’s Membrane Structures: Lipids (YouTube)

    Also available in:
    iTunes U
     
    Instructions:  Watch this lecture. The first part of this lecture covers irrelevant topics such as office hours, so you should begin watching at the 6 minute 30 second mark. This video will cover the material in subunit 2.1, 2.2, and all inclusive subunits.

    Watching this video and taking notes should take approximately 1 hour and 30 minutes.
     
    Terms of Use: This resource is released under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. It is attributed to the University of California, Berkeley and the original version can be found here.

2.1.1 Lipids, Sphingolipids, Glycolipids   This subunit is covered by the reading and video assigned beneath subunit 2.1. Focus specifically on the “Membrane Lipids” and “Membrane Proteins” sections in the reading.

2.1.2 Sterols   This subunit is covered by the reading and video assigned beneath subunit 2.1. Focus specifically on the subsection “Membrane Lipids” with associated figure (Fig. 2.47).

2.1.3 Triglycerides   This subunit is covered by the reading and video assigned beneath subunit 2.1. Focus specifically on the subsection “Membrane Lipids” with associated figure (Fig. 2.45).

2.2 Fluid Mosaic Model   This subunit is covered by the reading and video assigned beneath subunit 2.1. Focus specifically on the subsection “Membrane Lipids” with associated figure (Fig. 2.46).

2.2.1 Bilayer   This subunit is covered by the reading and video assigned beneath subunit 2.1. Focus specifically on the “Membrane Proteins” section in the reading.

2.2.2 Lipid Asymmetry   - Reading: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology, 4e: “Chapter 5: Biomembranes and the Subcellular Organization of Eukaryotic Cells” Link: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology, 4e: “Chapter 5: Biomembranes and the Subcellular Organization of Eukaryotic Cells” (HTML)
 
Instructions: Scroll down to and read the section titled “The Phospholipid Composition Differs in Two Membrane Leaflets.”
 
Reading this text and taking notes should take approximately 30 minutes.

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

2.3 Membrane Proteins   - Lecture: University of California, Berkeley: Professor Randy Schekman’s “Membrane Structures: Proteins” Link: University of California, Berkeley: Professor Randy Schekman’s Membrane Structures: Proteins (YouTube)

 Also available in:  
 [iTunes
U](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewiTunesUCollection?id=354820424)  
    
 Instructions: Watch this lecture.  

 Watching this lecture and taking notes should take approximately 2
hours.  
    
 Terms of Use: This resource is released under a [Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported
License](http://creativecommons.org/licenses/by-nc-nd/3.0/). It is
attributed to the University of California, Berkeley and the
original version can be found [here](http://webcast.berkeley.edu/).

2.3.1 Peripheral Proteins   This subunit is covered by the reading assigned beneath subunit 2.1. Focus specifically on the “Membrane Proteins” section.

2.3.2 Integral Proteins   This subunit is covered by the reading assigned beneath subunit 2.1. Focus specifically on the “Membrane Proteins” section.

2.4 Membrane Pumps   - Reading: National Center for Biotechnology Information’s Bookshelf: Sinauer Associates: Professor Geoffrey Cooper’s The Cell: A Molecular Approach, 2e: “Transport of Small Molecules” Link: National Center for Biotechnology Information’s Bookshelf: Sinauer Associates: Professor Geoffrey Cooper’s The Cell: A Molecular Approach, 2e: Transport of Small Molecules (HTML)
 
Instructions: Read this section, along with all associated figures (Figs.12.15–12.33). This will cover the materials in subunits 2.4–2.7.

 Reading this text and taking notes should take approximately 1
hour.  
    
 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above. 

2.4.1 Primary Transporters   This subunit is covered by the reading assigned beneath subunit 2.4. Focus on the subsection “Active Transport Driven by ATP Hydrolysis” with associated figure (Fig. 12.28).

2.4.2 Bacteriorhodopsin   - Reading: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology, 4e: “Chapter 3: Membrane Proteins” Link: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology, 4e: Chapter 3: Membrane Proteins (HTML)

 Instructions: Scroll down to and read the section titled “Many
Integral Proteins Contain Multiple Transmembrane α Helices.”  

 Reading this text and taking notes should take approximately 30
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

2.4.3 ATP-Drive Pumps   This subunit is covered by the reading assigned beneath subunit 2.4. Focus on the “Active Transport Driven by ATP Hydrolysis” section.

2.4.4 ABC (ATP-Binding Cassette) Transporters   This subunit is covered by the reading assigned beneath subunit 2.4. Focus on the “Active Transport Driven by ATP Hydrolysis” section and Figure 12.30. ABC transporters are important to the study of bacteria and immunology. You may have heard of super germs, or germs that are resistant to many of the antibiotics that doctors give to patients with infections. Super germs are antibiotic-resistant, because they have special ABC transporters that are designed to pump the drug out of the bacteria, reducing or even negating its effects.

2.5 Membrane Carriers   - Lecture: University of California, Berkeley: Professor Randy Schekman’s “Membrane Transport: Nucleocytoplasmic Exchange” Link: University of California, Berkeley: Professor Randy Schekman’s Membrane Transport: Nucleocytoplasmic Exchange (YouTube)

 Also available in:  
 [iTunes
U](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewiTunesUCollection?id=354820424)  
    
 Instructions: Watch this lecture. This will cover the material in
subunits 2.5, 2.6, and all inclusive subunits.  

 Watching this lecture and taking notes should take approximately 1
hour.  
    
 Terms of Use: This resource is released under a [Creative Commons
Attribution-NonCommercial-NoDerivs 3.0 Unported
License](http://creativecommons.org/licenses/by-nc-nd/3.0/). It is
attributed to the University of California, Berkeley and the
original version can be found [here](http://webcast.berkeley.edu/).

2.5.1 Uniporters, Antiporters, Symporters   This subunit is covered by the reading assigned beneath subunit 2.4 and the video assigned in subunit 2.5. Focus specifically on the “Active Transport Driven by Ion Gradients” section of the reading.

2.5.2 GLUT1 and GLUT4 (GLUcose Transporters)   This subunit is covered by the video assigned in subunit 2.5.

2.6 Membrane Channels   2.6.1 Sodium Channels   - Reading: National Center for Biotechnology Information’s Bookshelf: Sinauer Associates, Inc.: Purves, Augustine, Fitzpatrick, et al.’s (ed.) Neuroscience 2nd Edition: “Chapter 4: The Molecular Structure of Ion Channels” Link: National Center for Biotechnology Information’s Bookshelf: Sinauer   Associates, Inc.: Purves, Augustine, Fitzpatrick, et al.’s (ed.) Neuroscience, 2nd Edition: Chapter 4: The Molecular Structure of Ion Channels (HTML)

 Instructions: Read this webpage. The webpage also covers the topic
outlined in subunit 2.6.2.  

 Reading this text and taking notes should take approximately 1
hour.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.<span id="cke_bm_812E"
style="display: none;"> </span><span id="cke_bm_554E"
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style="display: none;"> </span><span id="cke_bm_552E"
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style="display: none;"> </span>

2.6.2 Potassium Channels   This topic is covered by the reading assigned beneath subunit 2.6.1. Focus on the subsection “The Molecular Structure of Ion Channels” and associated figure (Fig. 4.7).

2.6.3 Leak Channels and Membrane Potential   - Reading: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology: “Section 15.4: Intracellular Ion Environment and Membrane Potential” Link: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell BiologySection 15.4: Intracellular Ion Environment and Membrane Potential (HTML)

 Instructions: Scroll down the webpage, and read the section titled
“The Membrane Potential in Animal Cells Depends Largely on Resting
K<sup>+</sup> Channels.”  

 Reading this text and taking notes should take approximately 1
hour.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above

2.6.4 Water Channel   - Reading: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology: “Section 15.8: Osmosis, Water Channels, and the Regulation of Cell Volume” Link: National Center for Biotechnology Information’s Bookshelf: W.H. Freeman: H. Lodish, A. Berk, S.L. Zipursky, et al.’s Molecular Cell Biology: Section 15.8: Osmosis, Water Channels, and the Regulation of Cell Volume (HTML)

 Instructions: Scroll down the webpage, and read the section titled
“Water Channels Are Necessary for Bulk Flow of Water across Cell
Membranes.”  

 Reading this text and taking notes should take approximately 30
minutes.  
    
 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above

2.7 Membrane Physiology   2.7.1 Glucose Transport in Intestines   This subunit is covered by the reading assigned beneath subunit 2.4. Focus specifically on the “Active Transport Driven by Ion Gradients”  section.

2.7.2 Synthesis of ATP in Mitochondria   This subunit is covered by the reading assigned beneath subunit 2.4. Focus specifically on the “Active Transport Driven by ATP Hydrolysis” section.

  • Assessment: University of Arizona’s Biology Project: “Cell Biology” Link: University of Arizona’s Biology Project: Cell Biology (HTML)

    Instructions: In the “Cell Membranes” tutorial, answer questions 1–13.

    Completing this assessment should take approximately 1 hour.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.