Download Cell Structure and Function

CHAPTER 10
LESSON 2
Cell Structure and Function
The Cell
Key Concepts
What do you think? Read the two statements below and decide
whether you agree or disagree with them. Place an A in the Before
column if you agree with the statement or a D if you disagree. After
you’ve read this lesson, reread the statements to see if you have changed
your mind.
Before
Statement
• How are prokaryotic cells
and eukaryotic cells similar,
and how are they different?
• What do the structures in a
cell do?
After
3. Different organisms have cells with different
structures.
4. All cells store genetic information in their
nuclei.
3TUDY#OACH
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Cell Shape and Movement
Cells come in many shapes and sizes. The size and shape
of a cell is part of the function of the cell. Some cells, such
as human red-blood cells, can be seen only by using
a microscope. The cells can pass easily through small blood
vessels because of their small size. Their disk shapes are
important for carrying oxygen. Nerve cells have parts that
jut out. These projections on nerve cells can send signals
over long distances. Some plant cells are hollow. These
hollow cells make up tubelike structures that can carry water
and dissolved substances to parts of the plant.
The size and shape of a cell make it possible for the cell
to carry out its functions. The parts that make up a cell have
their own functions as well. A cell’s parts are like the players
on a football team who perform different tasks on the
playing field. A cell is made up of different parts that
perform different functions to keep the cell alive.
Reading Essentials
Use Prior Knowledge
Before you read this lesson,
look at the figures and
headings to learn what the
lesson is about. Write what
you know about the cell on a
piece of paper. As you read
the lesson, fill in what you
learned about the cell.
ACADEMIC VOCABULARY
function
(noun) the purpose for
which something is used
Cell Structure and Function
167
Plant Cell
Mitochondrion
Rough endoplasmic
reticulum
Ribosome
Smooth endoplasmic
reticulum
Central vacuole
Cytoskeleton
Visual Check
1. Describe the location of
the cell wall.
Vesicle
Cell wall
Genetic
material
Nucleus Nucleolus
Nuclear
membrane
Chloroplast
Cell membrane
Golgi apparatus
Cell Membrane
Reading Check
All cells have some parts, or structures, in common. One
of these structures is a cell membrane. A cell membrane is a
flexible covering that protects the inside of a cell from the environment
outside the cell. You can see the cell membrane in both
drawings on this page. Cell membranes are made of proteins
and phospholipids.
2. Describe What are cell
Centriole
Visual Check
Smooth
endoplasmic
reticulum
Lysosome
Cell membrane
Rough
endoplasmic
reticulum
3. Identify Circle the
names of two parts in the
animal cell that are also
found in the plant cell.
Vesicle
Nucleus
Genetic
material
Nucleolus
Nuclear
envelope
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Cell Structure and Function
Golgi
apparatus
Ribosome
Cytoskeleton
Mitochondrion
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Animal Cell
membranes made of?
Cell Wall
Every cell has a cell membrane. But some cells also have
a cell wall. Plant cells, fungal cells, bacterial cells, and some
protists have cell walls. A cell wall is a stiff structure outside the
cell membrane. A cell wall protects a cell from viruses and
other harmful organisms. In some plant and fungal cells, the
cell wall helps the cell keep its shape and gives it support.
Cell Appendages
If you look at a cell using a microscope, you might see
structures on the outside of the cell. These appendages might
look like hairs or long tails. They often help a cell move.
Flagella (fluh JEH luh) (singular, flagellum) are long and taillike. They whip back and forth to move the cell. Cilia (SIH lee
uh) (singular, cilium) are short, hairlike structures. They can
move a cell or move molecules away from a cell. The cilia in
your windpipe move harmful particles away from your lungs.
Cytoplasm and the Cytoskeleton
The fluid inside a cell is made of water, salts, and other molecules
and is called the cytoplasm. The cytoplasm contains a cell’s
cytoskeleton. The cytoskeleton is made of threadlike proteins that
are joined together. The cytoskeleton is a framework that gives
a cell its shape and helps it move.
4. Describe the structure
Cell Types
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Reading Check
Microscopes helped scientists discover that cells can be
grouped into two types. There are prokaryotic (proh ka ree
AH tihk) cells and eukaryotic (yew ker ee AH tihk) cells.
of the cytoskeleton.
Prokaryotic Cells
The genetic material in a prokaryotic cell is not
surrounded by a membrane. Look at the drawing below.
Prokaryotic cells also do not have many of the cell parts
other cells have. Most prokaryotic cells are unicellular
organisms and are called prokaryotes.
DNA
Visual Check
Ribosome
5. Name three parts of a
prokaryotic cell.
Cytoplasm
Flagellum
Cell
membrane
Cell wall
Capsule
Reading Essentials
Cell Structure and Function
169
Eukaryotic Cells
Key Concept Check
6. Compare and
Contrast How are
prokaryotic cells and
eukaryotic cells the same?
How are they different?
The cells of plants, animals, fungi, and protists are
eukaryotic cells. The genetic material of eukaryotic cells is
surrounded by a membrane. Every eukaryotic cell also has
organelles—other parts that are surrounded by a membrane and have
specialized functions. Eukaryotic cells are usually larger than
prokaryotic cells.
Cell Organelles
The organelles of eukaryotic cells have different functions
in the cell. Organelles help a cell carry out different
functions at the same time. These functions include getting
energy from food, storing information, and getting rid of
waste material.
The Nucleus
The largest organelle inside most eukaryotic cells is the
nucleus. The nucleus is the part of a eukaryotic cell that directs cell
activities and contains genetic information stored in DNA.
DNA is in structures called chromosomes. The number
of chromosomes in a nucleus is different for different species
of organisms.
SCIENCE USE V. COMMON USE
Science Use an outer covering
Common Use a flat paper
container for a letter
Manufacturing Molecules
Reading Check
7. Contrast smooth ER and
You learned that proteins are important molecules in
cells. Proteins are made of small organelles called ribosomes.
A ribosome is not surrounded by a membrane. Ribosomes
are in the cytoplasm of a cell. Ribosomes can be attached to
an organelle called the endoplasmic reticulum (en duh PLAZ
mihk • rih TIHK yuh lum), or ER. ER with ribosomes on its
surface is called rough ER. Rough ER is where proteins are
produced. ER without ribosomes on its surface is called
smooth ER. It makes lipids such as cholesterol. Smooth ER
also helps remove harmful substances from a cell.
rough ER.
170
Cell Structure and Function
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
envelope
The nucleus also contains proteins and an organelle
called the nucleolus (new KLEE uh lus). The nucleolus makes
ribosomes, organelles that help produce proteins. Two
membranes form the nuclear envelope that surrounds the
nucleus. The nuclear envelope has many pores. Certain
molecules, such as ribosomes and RNA, move into and out
of the nucleus through these pores.
Processing Energy
All living things must have energy to survive. Cells
process some energy in specialized organelles called
mitochondria (mi tuh KAHN dree uh) (singular,
mitochondrion). Most eukaryotic cells contain hundreds of
mitochondria. Some cells in a human heart can contain
1,000 mitochondria.
Make a half-book to record
information about cell
organelles and their
functions.
ATP A mitochondrion is surrounded by two membranes.
Chemical reactions within mitochondria release energy.
This energy is stored in high-energy molecules called ATP—
adenosine triphosphate (uh DEH nuh seen • tri FAHS fayt).
The energy in ATP molecules is used by the cell for growth,
cell division, and transporting materials.
Cell Organelles and Their Functions
Chloroplasts The cells of some organisms, such as plants
and algae, contain organelles called chloroplasts (KLOR uh
plasts). Chloroplasts are membrane-bound organelles that use light
energy and make food, a sugar called glucose, from water and carbon
dioxide in a process called photosynthesis (foh toh SIHN thuh sus).
The sugar has stored energy that can be used when the cells
need it.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Processing, Transporting, and Storing Molecules
The Golgi (GAWL jee) apparatus is an organelle that looks
like a stack of pancakes. It gets proteins ready for their
specific jobs. It then packages the proteins into tiny
membrane-bound, ball-like structures called vesicles.
Vesicles are organelles that transport substances to other
parts of the cell. Some vesicles in an animal cell are called
lysosomes. Lysosomes help break down and recycle different
parts of the cell.
Some cells also have structures called vacuoles (VA kyuh
wohlz). Vacuoles are organelles that store food, water, and
waste materials for a cell. A plant cell usually has one large
vacuole. Some animal cells have many small vacuoles.
Reading Essentials
Reading Check
8. Identify the types
of cells that contain
chloroplasts.
Key Concept Check
9. Explain the function of
the Golgi apparatus.
Cell Structure and Function
171
Mini Glossary
cell membrane: a flexible covering that protects the inside of
cytoskeleton: a network of threadlike proteins that are
a cell from the environment outside a cell
cell wall: a stiff structure outside the cell membrane
joined together
nucleus: the part of a eukaryotic cell that directs cell activities
and contains genetic information stored in DNA
chloroplast (KLOR uh plast): a membrane-bound
organelle that uses light energy and makes food—a sugar
called glucose—from water and carbon dioxide in a process
known as photosynthesis
organelle: a membrane-surrounded component of a cell that
has specialized functions
cytoplasm: a fluid inside a cell that contains salts and other
molecules
1. Review the terms and their definitions in the Mini Glossary. Write a sentence that lists
two functions of the nucleus of a eukaryotic cell.
2. Fill in the table below to identify the functions of each organelle.
Organelle
Function
Chloroplast
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Golgi apparatus
Smooth ER
Nucleus
3. Name three tasks carried out by the organelles of eukaryotic cells.
What do you think
Reread the statements at the beginning of the
lesson. Fill in the After column with an A if you
agree with the statement or a D if you disagree.
Did you change your mind?
172
Cell Structure and Function
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LESSON
Reading Essentials