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Specialized Animal Cells
Cell Specialization
thin cell
wall
middle
plant cells are found in the
0 Thin-walled
fiexibie tissues of the leaf, fiower, fruit,
and root. Most edibie olant oots, such
as potatoes and racishes, are
composed of these celLs.
thicker
cell wall
plant cells are speciahzed
0 Thick-walled
for support. Tneir stre:chabie ccl. wal.s
are flexible. The tough strings of the
celery stalk are made of rnese cells.
thickest
cell wall
O
Very thick cell walls provide rigid
support. The cell wall can get so thick,
as the piant matures, that it becomes
difficult for nutrients to enter the cel1.
The cell usually dies, leaving an empty
chamber surrounded by a thick wall.
Fabrics such as linen are made from
these cells.
i’iiI
Plants, like animals, are made of tissues
and organs. Each kind of tissue contains
a special type of cell.
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Unit I
Understanding Concepts
The shape of animal cells provides a clue to their function.
Many of the features of unicellular organisms can he
found in animal cells as you can see in Figure 2.
Imagine how difficult life would be
without specialists. Could you build
your own television? Grow your own
food? Do your own stugery?
Unicellular organisms are not
specialists. Each cell must carry out
all the functions of life. Multicellular
organisms, such as you, benefit from
cell specialization. We have cells that
come in a variety of sizes and shapes,
each designed to carry out a special
function.
tissue
0 Nerve
Nerve ceils tend to be
:or.g ad tnin. Many nerve
cells are protected by
a coating of insulation
that prevents short
circuits.
I, i’i
Some speciai.zed cells found
in
bodies.
respiratory system
0 The
OParticles that artempi to
enter your iurgs a-e trappea
in mucoJs ano men swept
away from the lungs by cells
with cilia.
Ocells of the lung are very
thin. This allows gases to
exchange rapidy between
tke air and the blood.
1. What are the advantages of cell
specialization for an organism?
2. Predict what might happen
to multicellular plants if a
microorganism that digests
pectin was accidentally released
from a laboratory.
3. What is the advantage of a
highly folded cell membrane?
4. What advantage does a thick,
flexible plant cell wall provide
over a thick, rigid cell wall?
5. Examine the cell shape in Figure 3:
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lAS! I’! in
Specialized Plant Cells
The long, thin strings inside a celery
stalk, the pit in an apricot, the thin
leaves of the lettuce are all evidence
that there is a variety of different
types o plant cells (Figure 1).
The cell wall is one very
noticeable feature of plant cells. As
plants develop, a primary cell wall is
formed around each cell. Once the
plant stops growing, an additional
secondary cell wall may Form inside
the primary cell wall. This structure
provides added strength.
The spaces between plant cells,
referred to as the middle larnellae,
contain a sticky, sugary substance
called pectin. Pectin acts like cement,
sticking plant cells together The
sticky syrup that often forms on the
top of a baked apple pie is pectin.
stomach
0 The
You stomach contains a
tissue
0 Blood
o Red olood cells carry
powerful acid, cells of the
lining of the stomach are
protected from the acid by a
layer of mucous. These cells
also have many GolgI
apparat,ses to store the
prote rs that break down food.
oxygen in a specai
protein called
hemoglobin. The
cells are filled with
this protein.
Qwhite blood cells
orotect the body from
invaders by engulfing
them and digesting
them, or by killing
them with antibodies.
a
r
“
Three cell shapes
(a) Which cell would be best
suited as an egg cell? Give
your reasons.
(b) Which cell would be best
suited for movement? Give
your reasons,
(c) Which cell would be best
suited as a covering for an
organ? Give your reasons.
6. Identify body cells that have a
structure similar to that of a
unicellular organism.
Reflecting
7. Why are specialized cells
dependent on other specialized
cells?
jsign Challenge
Is the structure of the
Fat tissue
In fat cells,
most of the
cytoplasm is
occupied by a
vacuole that
stores at
molecules.
The small intestine
Ce.ls that inc t”e small
intest.ne absoro food.
Fingerlike projections
increase the surface
area for absorption.
cell that you are building
suited for its special
function? What changes
should you make in your
design now that you
know more about
specialized cells?
(‘//c, ‘Fiscut’, Orga iii, and Sy.cte,n.c
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