Chapter 4 - Cells: The working units of life
Hillis et al., chapter 4
Note: We will cover microscopy and cell fractionation in lab
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
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
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
Rough ER (4.8)
Mitochondrion Produces ATP for GCase
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
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
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
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
a. Which junction allows the free passage of small molecules between adjacent
b. What is the function of desmosomes? How is keratin useful in supporting this
c. What function do tight junctions serve – where would you expect ehose?
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).