Chapter 3
Cells: The Living Units
115
3
4.
Te normal function of one tumor suppressor gene is to prevent cells
with damaged chromosomes and DNA from “progressing from G
1
to S,” whereas another tumor suppressor gene prevents “passage from
G
2
to M.” When these tumor suppressor genes fail to work, cancer can
result. Explain what the phrases in quotations mean.
5.
In their anatomy lab, many students are exposed to the chemical
preservatives phenol, formaldehyde, and alcohol. Our cells break
down these toxins very effectively. What cellular organelle is
responsible for this?
6.
Dynein is missing from the cilia and flagella of individuals with
a specific inherited disorder. Tese individuals have severe
respiratory problems and, if males, are sterile. What is the
structural connection between these two symptoms?
7.
Explain why alcoholics are likely to have much more smooth ER
than teetotalers.
8.
Fresh water is a precious natural resource in Florida and it is said
that supplies are dwindling. Desalinizing (removing salt from)
ocean water has been recommended as a solution to the problem.
Why shouldn’t we drink salt water?
Critical Thinking
and Clinical Application
Questions
1.
Explain why limp celery becomes crisp and the skin of your
fingertips wrinkles when placed in tap water. (Te principle is
exactly the same.)
2.
A “red-hot” bacterial infection of the intestinal tract irritates the
intestinal cells and interferes with digestion. Such a condition is
o±en accompanied by diarrhea, which causes loss of body water.
On the basis of what you have learned about osmotic water flows,
explain why diarrhea may occur.
3.
²wo examples of chemotherapeutic drugs (drugs used to treat
cancer) and their cellular actions are listed below. Explain why
each drug could be fatal to a cell.
Vincristine (brand name Oncovin): damages the mitotic
spindle
Doxorubicin (Adriamycin): binds to DNA and blocks mRNA
synthesis
Related Clinical Terms
Anaplasia
(an
9
ah-pla
9
ze-ah;
an
5
without, not;
plas
5
to grow)
Abnormalities in cell structure and loss of differentiation;
for example, cancer cells typically lose the appearance of
the parent cells and come to resemble undifferentiated or
embryonic cells.
Dysplasia
(dis-pla
9
ze-ah;
dys
5
abnormal) A change in cell size,
shape, or arrangement due to chronic irritation or inflammation
(infections, etc.).
Hypertrophy
(hi-per
9
tro-fe) Growth of an organ or tissue due to an
increase in the size of its cells. Hypertrophy is a normal response
of skeletal muscle cells when they are challenged to li± excessive
weight; differs from hyperplasia, which is an increase in size due
to an increase in cell number.
Liposomes
(lip
9
o-sōmz) Hollow microscopic sacs formed of
phospholipids that can be filled with a variety of drugs. Serve as
multipurpose vehicles for drugs, genetic material, and cosmetics.
Mutation
A change in DNA base sequence that may lead to
incorporation of incorrect amino acids in particular positions
in the resulting protein; the affected protein may remain
unimpaired or may function abnormally or not at all, leading to
disease.
Necrosis
(nĕ-kro
9
sis;
necros
5
death;
osis
5
process) Death of a cell
or group of cells due to injury or disease. Acute injury causes the
cells to swell and burst, and induces the inflammatory response.
(Tis is uncontrolled cell death, in contrast to apoptosis
described in the text.)
AT T H E C L I N I C
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