Cells: The Living Units
Te normal function of one tumor suppressor gene is to prevent cells
with damaged chromosomes and DNA from “progressing from G
to S,” whereas another tumor suppressor gene prevents “passage from
to M.” When these tumor suppressor genes fail to work, cancer can
result. Explain what the phrases in quotations mean.
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?
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?
Explain why alcoholics are likely to have much more smooth ER
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?
and Clinical Application
Explain why limp celery becomes crisp and the skin of your
ﬁngertips wrinkles when placed in tap water. (Te principle is
exactly the same.)
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.
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
Doxorubicin (Adriamycin): binds to DNA and blocks mRNA
Related Clinical Terms
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
abnormal) A change in cell size,
shape, or arrangement due to chronic irritation or inﬂammation
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.
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.
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
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