Download Plant and Animal Cell Structures - CK

Plant and Animal Cell
Structures
Say Thanks to the Authors
Click http://www.ck12.org/saythanks
(No sign in required)
To access a customizable version of this book, as well as other
interactive content, visit www.ck12.org
CK-12 Foundation is a non-profit organization with a mission to
reduce the cost of textbook materials for the K-12 market both in
the U.S. and worldwide. Using an open-source, collaborative, and
web-based compilation model, CK-12 pioneers and promotes the
creation and distribution of high-quality, adaptive online textbooks
that can be mixed, modified and printed (i.e., the FlexBook®
textbooks).
Copyright © 2015 CK-12 Foundation, www.ck12.org
The names “CK-12” and “CK12” and associated logos and the
terms “FlexBook®” and “FlexBook Platform®” (collectively
“CK-12 Marks”) are trademarks and service marks of CK-12
Foundation and are protected by federal, state, and international
laws.
Any form of reproduction of this book in any format or medium,
in whole or in sections must include the referral attribution link
http://www.ck12.org/saythanks (placed in a visible location) in
addition to the following terms.
Except as otherwise noted, all CK-12 Content (including CK-12
Curriculum Material) is made available to Users in accordance
with the Creative Commons Attribution-Non-Commercial 3.0
Unported (CC BY-NC 3.0) License (http://creativecommons.org/
licenses/by-nc/3.0/), as amended and updated by Creative Commons from time to time (the “CC License”), which is incorporated
herein by this reference.
Complete terms can be found at http://www.ck12.org/about/
terms-of-use.
Printed: June 23, 2015
www.ck12.org
C HAPTER
Chapter 1. Plant and Animal Cell Structures
1
Plant and Animal Cell
Structures
Lesson Objectives
• Discuss the structure and function of the cell membrane and cytoplasm.
• Describe the structure and function of the nucleus.
• Distinguish between plant and animal cells.
Check Your Understanding
• What is a cell?
• How do we visualize cells?
Vocabulary
•
•
•
•
•
cell wall
cell membrane
chloroplast
cytoplasm
nucleus
The Plasma Membrane and Cytoplasm
All cells have boundaries around them that separate them from other cells and make sure the parts of the cell do
not just float away. That boundary is called the cell membrane. The function of the cell membrane is to control
what goes into and out of the cell. There are some molecules that the cell needs and they are allowed in through the
cell membrane. On the other hand, there are some molecules that the cell has to get rid of, so they are allowed out
through the cell membrane. The cell membrane also prevents materials the cell needs from leaving, as well as those
it does not need from entering.
Just beneath the cell membrane, one would find a gel-like substance, called cytoplasm, filling the cell. Cytoplasm
is composed of water and other molecules, including enzymes that speed up the cell’s chemical reactions. All of
the parts of the cell sit in the cytoplasm, like fruit in a Jell-O mold. Because of its composition, many of the cell’s
necessary processes take place in the fluid cytoplasm.
The Nucleus
The nucleus is a large, membrane-bound structure that contains most of the genetic material (DNA) of the cell. The
important genetic information held within the nucleus helps the cell create important molecules for life. Because of
this, the nucleus is often referred to as the "control center" or the "brain" of the cell.
Differences between Plant and Animal Cells
Plant cells differ in some ways from animal cells.
1
www.ck12.org
Plant cells have a cell wall surrounding their cell membrane, while animal cells do not. A cell wall is a rigid structure
that gives the plant cell support, strength, and protection. Animal cells do not need this because most animals have
other structures, such as skeletons, that support them.
See the figure below that shows both a plant cell and an animal cell. Notice the structures they have in common and
the differences.
FIGURE 1.1
Plant cells also have structures called chloroplasts that animal cells do not have. Chloroplasts are the site of
photosynthesis, which is the way that plants capture sunlight and turn it into food. Chloroplasts contain a green
pigment called chlorophyll. This pigment not only helps the chloroplast to capture sunlight, but also gives plants
their green color.
FIGURE 1.2
This photo of plant cells taken with a light microscope shows green
chloroplasts, as well as a cell wall around each cell.
Lesson Summary
• Each component of a cell has a specific function.
• Plant cells are different from animal cells. For example, plant cells contain chloroplasts and cell walls.
Review Questions
Apply Concepts
1. What is the cell membrane and what is its role?
Think Critically
2. Why does photosynthesis not occur in animal cells?
2
www.ck12.org
Chapter 1. Plant and Animal Cell Structures
Points to Consider
• Think about what molecules would need to be transported into cells.
• Discuss why you think it would be important for some molecules to be kept out of a cell.
Missouri Standards
3.2.A.a
References
1. Kelvin Song. http://commons.wikimedia.org/wiki/File:Moss_chloroplasts_100%C3%97_objective_oblique
.jpg .
3