Download Lecture Suggestions and Guidelines

CHAPTER 3
CELLS
LEARNING OBJECTIVE 1: Explain how cells differ from one another.
Lecture Suggestions and Guidelines
1. Give an overview of the cellular basis of life.
2. Describe the relationship between the structure and the function of cells within the
human body.
3. Compare the size, shape, and function of various cell types.
Application Question(s)
1. Cells vary tremendously in size. Ask students to cite specific examples of cells
within the human body which illustrate this phenomenon.
Answer: Some possible examples might include bacteria (2 micrometers in
diameter) and nerve cells (1 meter in length).
2. Cells vary dramatically in function. Ask students to cite specific examples of cells
within the human body which illustrate this phenomenon.
Answer: Examples might include white blood cells (immunity, phagocytosis) and
nerve cells (nerve impulse conduction).
Critical Thinking Issue(s)
1. How might the light microscope be limited as a tool for studying cellular structure
and function?
Answer: Micrographs produced using the light microscope are typically twodimensional. The maximum effective magnification possible is about 1200x.
LEARNING OBJECTIVE 2: Describe the general characteristics of a composite cell.
Lecture Suggestions and Guidelines
1. Introduce the generalized anatomy of a composite cell.
2. Describe the three major parts of a cell: the nucleus, the cytoplasm, and the cell
membrane.
3. Introduce a model of a composite cell and ask students to draw it based on their
observations.
Application Question(s)
1. Although cells vary dramatically in size, shape, and function, what are some
characteristics, which are common to all cells?
Answer: In general, all cells have three main regions: the nucleus, which serves
as the headquarters of the cell; the cytoplasm, which contains organelles that carry
out very specific functions; and a cell membrane, which keeps the cell intact by
providing a boundary and by allowing the transport of substances into and out of
the cell.
Critical Thinking Issue(s)
1. Consider the mature red blood cell. It is unlike many other cells in that it is
anucleate, i.e., lacks a nucleus and contains very few organelles. In fact, mature
red blood cells lack mitochondria, the “powerhouses” of the cell. Why is it
important that red blood cells lack mitochondria?
Answer: Red blood cells manufacture adenosine triphosphate (ATP) by anaerobic
mechanisms and thus do not deplete the stores of oxygen they are transporting to
other parts of the body.
LEARNING OBJECTIVE 3: Explain how the components of a cell’s membrane
provide its functions.
Lecture Suggestions and Guidelines
1. Introduce the components of cell membrane structure: lipids and proteins with a
small quantity of carbohydrates.
2. Explain the phospholipid bilayer and introduce the terms hydrophilic and
hydrophobic.
3. Discuss proteins, which provide the special functions of the membrane.
Application Question(s)
1. Ask students to discuss the varied roles of proteins, which are scattered
throughout the lipid bilayer of the cell membrane.
Answer: Some proteins serve as enzymes, some are receptors or binding sites,
and still others are involved in transport functions. When proteins combine with
sugars to become glycoproteins, they can, among other things, determine a
patient’s blood type.
2. What causes Hyperkalemic Periodic Paralysis?
Answer: See textbook Clinical Application.
Critical Thinking Issue(s)
1. Cell surface glycoproteins mark the cells of individuals as “self.” Give an
example of an autoimmune disease in which this system fails.
Answer: An example would be rheumatic heart disease in which a
streptococcus infection migrates to heart tissue. In an attempt to destroy the
foreign bacteria, the immune system recognizes the patient’s healthy tissue as
foreign and proceeds to damage it.
LEARNING OBJECTIVE 4: Describe each kind of cytoplasmic organelle and explain
its function.
Lecture Suggestions and Guidelines
1. Introduce the major organelles of a composite cell and describe the function of
each.
2. A very effective learning tool is to ask the students to devise a chart, which lists
all major organelles in one column and the corresponding function in the next
column. Reinforce this with flash cards. Write the name of the organelle on one
side, and briefly describe its function on the other side. Make a second set of flash
cards by reversing the front and back information.
Application Question(s)
1. Ask students to sketch their interpretation of how proteins, which are tagged for
export, are ejected from the cell.
Answer: Drawings will vary, but should illustrate that proteins accumulate in the
Golgi apparatus, then the membranous sacs swell until their swollen ends are
pinched off to form secretory vesicles which migrate to the cell membrane, where
they finally fuse with the membrane, rupture, and eject the contents to the cell’s
exterior.
Critical Thinking Issue(s)
1. Explain how proteins synthesized on the rough endoplasmic reticulum insert into
the cell membrane.
Answer: They are incorporated into the membrane of the secretory vesicle. The
vesicle fuses with the cell membrane and any proteins in the vesicle membrane
become membrane proteins of the cell. How these proteins insert into the
membrane depends on hydrophilic and hydrophobic regions in the protein.
LEARNING OBJECTIVE 5: Describe the cell nucleus and its parts.
Lecture Suggestions and Guidelines
1. Describe the cell nucleus, nuclear membrane, nucleoli, and chromatin.
2. Introduce DNA as the genetic material, which acts as a blueprint for the entire
body.
Application Question(s)
1. How might DNA be compared to a strip of magnetic recording tape?
Answer: Its information is not useful until it is decoded. DNA requires not only a
decoding mechanism, but also a messenger in the form of RNA to specify the
structure of proteins.
Critical Thinking Issue(s)
1. A wide variety of drugs are currently used in the treatment of cancer. Some of
these drugs act to interrupt cellular activity by disrupting the mitotic scaffolding,
which appears during prophase. How might these drugs be fatal to a cell?
Answer: The mitotic spindle provides a foundation for the attachment and
movement of chromosomes during cell division. If the scaffolding is disrupted,
normal chromosome alignment cannot take place.
LEARNING OBJECTIVE 6: Explain how substances move into and out of cells.
Lecture Suggestions and Guidelines
1. Discuss active and passive transport.
2. Give examples of passive transport, including diffusion, osmosis, and filtration.
3. Give examples of active transport processes, including solute pumping,
exocytosis/endocytosis, and phagocytosis/pinocytosis.
Application Question(s)
1. Two patients visit the ER of a local hospital. Patient A appears to be edemic, with
swollen hands and feet, due to water retention. Patient B is dehydrated due to
excessive exercise under a hot sun. What kind of IV therapy might each patient be
prescribed, i.e., a hypotonic solution or a hypertonic solution? Why?
Answer: Patient A would receive a hypertonic solution, for example, 5% NaCl.
This will crenate the cells by allowing water to leave the cell into the bloodstream
to be excreted. Patient B would receive a hypotonic solution, for example, 0.18%
NaCl, to rehydrate the tissues, since this solution contains fewer solutes than are
inside the cell.
Critical Thinking Issue(s)
1. How might hemodialysis illustrate the concept of selective permeability?
Answer: The hemodialyzed patient’s blood is passed through selectively
permeable membrane tubing, i.e., permeable only to certain substances. As the
patient’s blood circulates through this tubing, potassium ion and nitrogenous
wastes diffuse out of the blood, while hydrogen ion buffers move from a bathing
solution into the blood.
LEARNING OBJECTIVE 7: Describe the cell cycle.
and
LEARNING OBJECTIVE 8: Explain how a cell divides.
Lecture Suggestions and Guidelines
1. Describe the events of cell division, including mitosis and cytokinesis.
2. Use the acronym PMATI - Please Memorize All This Information - as a tool to
assist students in learning the cell cycle phases - Prophase Metaphase Anaphase
Telophase Interphase.
3. Distribute copies of textbook figure to students as a study aid.
Application Question(s)
1. Ask students to roughly sketch each phase of the cell cycle. Draw each phase on a
separate index card and shuffle them. Students should attempt to place the cell
cycle phases in the correct order and describe at least two major events, which
occur in each of the phases.
Critical Thinking Issue(s)
1. Upon maturity, some groups of cells become amitotic. Give an example of this
type of cell and explain why injury or trauma to amitotic cells may have
devastating effects.
Answer: Amitotic cells lose the ability to divide and reproduce similar or “like”
cells. Examples would include nerve cells or heart muscle cells. A patient who
has experienced a severe heart attack will replace healthy heart cells with scar
tissue, which will inhibit the heart from working at full capacity.
2. Viruses lack the cellular machinery to reproduce themselves, yet manage to
survive. Explain how this might happen and describe a natural antimicrobial
chemical, which aids humans in combating viral attacks.
Answer: Viruses damage the body by entering cells and confiscating the
components necessary to reproduce themselves. Virus-infected cells can secrete
interferons which bind to healthy cell membranes and interfere with viral
replication.
LEARNING OBJECTIVE 9: Describe several controls of cell division.
Lecture Suggestions and Guidelines
1. Introduce the internal and external factors, which control cell reproduction.
2. Discuss the health consequences of the loss of cell reproduction and control.
Application Question(s)
1. Ask the students to bring to class information from a recent newspaper or
magazine article or from an experience with which they are familiar regarding
cancer. Allow the students to highlight major points and share their information
with the class. Which cancers were classified as benign? Malignant? Which kinds
of cancer were reported to be the most common? Rarest? What kinds of treatment
are currently available, etc. Discuss and summarize these findings with the class.
Answer: N/A
Critical Thinking Issue(s)
1. Cloning has come to the forefront as an issue of major concern for both scientists
and the general population. Divide the classroom into groups of students. Group
A represents scientists who support cloning in the interest of furthering scientific
knowledge and understanding. Group B represents a religious sector, which
refutes the value of such experimentation. Group C represents a capitalistic
company that stands to profit greatly from the “future of cloning.” Group D
represents the federal government, which must decide to support or oppose future
cloning experimentation. Allow students to debate any relevant issues
surrounding the controversy overcloning.
Answer: N/A
LEARNING OBJECTIVE 10: Explain how stem cells and progenitor cells make
possible growth and repair of tissues.
Lecture Suggestions and Guidelines
1. Discuss how a stem cell divides.
2. Introduce the concepts of totipotent and pluripotent cells.
3. Reiterate the phenomenon of cell specialization.
Application Question(s)
1. Ask students to create a chart depicting the division of a stem cell that gives rise
to differentiated cells of a restricted lineage.
Answer: Responses will vary.
Critical Thinking Issue(s)
1. Ask students to write a short essay that supports an opinion regarding the cloning
of human cells.
Answer: This essay will provide an excellent opportunity to perform a SWOT
analysis (strengths, weaknesses, opportunities and threats).
SUGGESTIONS FOR ADDITIONAL READING
Barinaga, Marcia. April 23, 1993. Secrets of secretion revealed. Science, vol. 260. A fleet
of vesicles carries out the process of secretion, stopping at various organelles.
Bayley, Hagan. September 1997. Building Doors into Cells. Scientific American.
Cech, Thomas R. October 21, 1994. Chromosome end games. Science, vol. 266. Once
thought not to be very important, we now know that telomeres are vital for
chromosome stability and for control of cell division.
Ember, Lois R. November 28, 1994. The nicotine connection. Chemistry & Engineering
News, vol. 72. Tobacco addiction results from activity at cell surfaces.
Folkman, Judah. January 1995. Angiogenesis in cancer, vascular, rheumatoid, and other
diseases. Nature Medicine, vol. 1. Cell division not only causes a tumor to grow, but
also provides a blood vessel supply to the abnormal tissue.
Glover, David M., Cayetano Gonzales, and Jordan W. Raff. June 1993. The centrosome.
Scientific American. A complex interplay between microtubules and other
cytoskeletal elements helps cells divide.
Hartwell, Leland H. and Michael B. Kastan. December 16, 1994. Cell cycle control and
cancer. Science, vol. 266.
Cell biology is revealing how cancer arises.
Lewis, Ricki. March 1994. Gateway to the brain. BioScience, vol. 44. Understanding the
function of the blood-brain barrier leads to development of new drug delivery
systems.
Lewis, Ricki. February 6, 1995. Cell death a lively area. The Scientist. At the cellular
level, death is a part of life.
Marx, Jean. December 1994. Oncogenes reach a milestone. Science, vol. 266.
Understanding oncogenes has helped explain cancer as well as normal cell function.
Miller, Robert V. January 1998. Bacterial Gene Swapping in Nature. Scientific American.
PantJ, Welly, and Veli Aebi. September 1993. The nuclear pore complex. Journal of Cell
Biology, vol. 122, no. 5. Nuclear pores are much more than simple holes.
Rodan, Eduardo R.S., Murase Tetsuma, and Qi-Xian Si. December 2, 1994. Exocytosis in
spermatozoa in response to progesterone and zona pellucida. Science, vol. 266.
Exocytosis releases enzymes from a sperm’s tip that enable it to penetrate the ovum.
Spudich, James. December 8, 1994. How molecular motors work. Nature, vol. 370.
Molecules that move keep a cell active.
Thompson, Dick. September 28, 1992. The glue of life. Time. People missing adhesion
molecules live dangerously.
Valle, David, and Jutta Gartner. February 25, 1993. Penetrating the peroxisome. Nature,
vol. 361.
Adrenoleukodystrophy is caused by a missing or abnormal peroxisomal protein—but not
the one researchers had suspected.