111
CHAPTER THREE
Cells
3.6
STEM AND PROGENITOR CELLS
(PAGE 105)
1. A stem cell divides to yield another stem cell and a
partially differentiated progenitor cell.
2. Cells that give rise to any differentiated cell type
are totipotent. Cells with more restricted fates are
pluripotent.
3. Stem cells may be present in adult organs or migrate
from the bone marrow to replace damaged cells—or
both.
4. As cells specialize, they express different sets of genes
that provide their distinct characteristics.
3.7
CELL DEATH (PAGE 106)
1. Apoptosis is a form of cell death that is part of normal
development and growth.
2. It is a fast, orderly multistep process that begins
when a cell surface receptor receives a signal to die.
Caspases start a chain reaction that cuts up the cell
into membrane-encapsulated pieces, and F
nally a
phagocyte destroys the remains.
3. Apoptosis and mitosis are in balance.
3. Mitosis
a. Mitosis is the division and distribution of DNA to
daughter cells.
b. The stages of mitosis include prophase, metaphase,
anaphase, and telophase.
4. The cytoplasm divides into two portions with the
completion of mitosis.
3.5
CONTROL OF CELL DIVISION (PAGE 103)
1. Cell division capacities vary greatly among cell types.
2. Chromosome tips that shorten with each mitosis
provide a mitotic clock, usually limiting the number
of divisions to F
fty.
3. Cell division is limited and controlled by both internal
and external factors.
4. As a cell grows, its surface area increases to a lesser
degree than its volume, and eventually the area
becomes inadequate for the requirements of the
living material within the cell. When a cell divides,
the daughter cells have more favorable surface area-
volume relationships.
5. Growth factors and hormones also stimulate cell
division.
6. Cancer is the consequence of a loss of cell cycle control.
3.1 Introduction
1
An adult human body consists of about ______ cells. (p. 76)
a. 2 billion
b. 50 to 100 billion
c. 50 to 100 trillion
d. 8 quadrillion
2
Describe three types of diF
erentiated cells. (p. 76)
3.2 A Composite Cell
3
The three major parts of a cell are ______________. (p. 76)
a. the nucleus, the nucleolus, and the nuclear envelope
b. the nucleus, the cytoplasm, and the cell membrane
c. a nerve cell, an epithelial cell, and a muscle cell
d. the endoplasmic reticulum, the Golgi apparatus, and
ribosomes
e. the cytoplasm, the organelles, and the chromatin
4
Distinguish between the cytoplasm and the cytosol of a
cell. (p. 76)
5
Explain the general function of organelles. (p. 76)
6
De±
ne
selectively permeable.
(p. 79)
7
Describe the structure of a cell membrane and
explain how this structural organization provides the
membrane’s function. (p. 79)
8
List three functions of membrane proteins. (p. 80)
9
State a way that cellular adhesion is essential to health
and a way that abnormal cellular adhesion harms health.
(p. 81)
CHAPTER ASSESSMENTS
10
Match the following structures with their de±
nitions:
(pp. 82–89)
(1) Golgi apparatus
(2) mitochondria
(3) peroxisomes
(4) cilia
(5) endoplasmic
reticulum
(6) cytoskeleton
(7) vesicles
(8) ribosomes
A. Sacs that contain enzymes that
catalyze a variety of speci±
c bio-
chemical reactions
B. Structures on which protein syn-
thesis occurs
C. Structures that house the reactions
that release energy from nutrients
D. A network of micro±
laments and
microtubules that supports and
shapes a cell
E. A structure that modi±
es, pack-
ages, and exports glycoproteins
². Membrane-bounded sacs
G. A network of membranous chan-
nels and sacs where lipids and
proteins are synthesized
H. Hairlike structures that extend
from certain cell surfaces and
wave about
11
Distinguish between organelles and inclusions. (p. 89)
12
List the parts of the nucleus and explain why each is
important. (p. 89)
3.3 Movements Into and Out of the Cell
13
Distinguish between active and passive mechanisms of
movement across cell membranes. (p. 90)
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