AT our of the Cell

							               Chapter 4 - Cells: The working units of life

Hillis et al., chapter 4
Note: We will cover microscopy and cell fractionation in lab

0. Application
   1. What are the most common symptoms of Gaucher's disease?
   2. What is the cause of Gaucher's disease? If you have real player installed, you can listen
      to a narrated power point presentation available at
      http://fog.ccsf.edu/~cpogge/gauchervideo.ram.

I. The big picture
Let's see how the material covered so far that will help us integrate the information on structures
within cells and their function.
    3. The seven characteristics of life (week 1) gave us an overview of what tasks cells have
        to perform: give examples.
    4. Also in chapter one, we learned how organisms evolve adaptations to changing
        environments as solutions to the challenges of life: give examples.
    5. The chapters on biochemistry provided us with knowledge of the chemical composition
        of cells: review the six most common elements and which molecules are used to build
        structures such as the plasma membrane, DNA, cell walls, energy storage; how atoms
        bond and dissociate, review the strong and weak bonds important in biology and
        especially important is the realization that most of these chemical reactions take place in
        an aqueous environment.

II. A tour of cells
   6. State the three components of the cell theory.
   7. Explain why there are both upper and lower limits to cell size (Fig. 4.2).
   8. Compare and contrast prokaryotic and eukaryotic cells. Make a mental note that E.
      coli, the bacterium that we will work with in lab, has an outer membrane such as the one
      depicted in Figure 4.5.
   9. Let's create a story about how the subcellular cell components are involved in making a
      protein called glucocerebrosidase (GCase) that cells need in order to digest a
      particular glycolipid named glucocerebroside (GC). This protein is misfolded in people
      with Gaucher’s disease. To create the story, fill in the following table (Fig. 9 is
      particularly helpful).

Structure               Describe structure      Function of            The story
                        (1-2 characteristics)   structure
Nucleus                                                                holds information on how
                                                                       to make GCase in the
                                                                       form of DNA. When GC
                                                                       needs to be broken down,
                                                                       proteins in the nucleus
                                                                       transcribe the DNA into
                                                                       mRNAs which leave the
                                                                      nucleus through nuclear
                                                                      pores and binds to
Ribosome
Rough ER (4.8)


Transport
vesicle/motor
proteins/micro-tubules
(4.13)
Golgi
Lysosome (4.9)
Smooth ER
Mitochondrion                                                         Produces ATP for GCase
                                                                      synthesis


   10. Describe form and function of the endomembrane system (Fig. 4.8) and animated
       tutorial 4.2 on BioPortal.
   11. Explain how the compartmental organization of a eurkaryotic cell contributes to its
       biochemical function.

III. The Cytoskeleton and extracellular structures
What holds the cell of a multicellular organism together? Remember, a cell is a little droplet of
water surrounded by a flimsy layer of lipids – but together they can form organisms as ordered
and solid as a tree or a bear. What keeps cells together, allows cooperation, and provides
stability?
    12. Compare the structure, composition, and functions of microtubules, microfilaments,
         and intermediate filaments. Give an example for each (Fig. 4.10).
    13. Explain the following sentence (p. 70): “…dynamic instability is a hall mark of the
         cytoskeleton”.
    14. How do the two manipulative approaches described on page 72 demonstrate cause and
         effect of molecular processes?
    15. List four functions of the extracellular matrix (ECM) in animal cells (Fig. 6.30) and its
         structure and contrast the ECM of epithelial and connective tissue.
    16. What is the function of cell junctions?
    17. Compare and contrast tight junctions, desmosomes, and gap junctions (Figure
         4.18).
             a.    Which junction allows the free passage of small molecules between adjacent
                   cells?
             b.    What is the function of desmosomes? How is keratin useful in supporting this
                   function?
             c.    What function do tight junctions serve – where would you expect ehose?
Essay question
  Describe the function and synthesis of glucocerebrosidase. Explain how nonfunctional
  glucocerebrosidases can lead to Gaucher’s disease. For full credit you should describe the
  subcellular structures mentioned (form and function).