Chapter 3 - The Cellular Level of Organization - CHAPTER 3...

3 | THE CELLULAR LEVEL
OF ORGANIZATION
Figure 3.1 Flourescence-stained Cell Undergoing Mitosis A lung cell from a newt, commonly studied for its
similarity to human lung cells, is stained with fluorescent dyes. The green stain reveals mitotic spindles, red is the
cell membrane and part of the cytoplasm, and the structures that appear light blue are chromosomes. This cell is in
anaphase of mitosis. (credit: “Mortadelo2005”/Wikimedia Commons)
Introduction
Chapter Objectives
After studying this chapter, you will be able to:
• Describe the structure and function of the cell membrane, including its regulation of materials into and out
of the cell
• Describe the functions of the various cytoplasmic organelles
• Explain the structure and contents of the nucleus, as well as the process of DNA replication
• Explain the process by which a cell builds proteins using the DNA code
• List the stages of the cell cycle in order, including the steps of cell division in both somatic cells
• Discuss how a cell differentiates and becomes more specialized
• List the morphological and physiological characteristics of some representative cell types in the human body
You developed from a single fertilized egg cell into the complex organism containing trillions of cells that you see when
you look in a mirror. During this developmental process, early, undifferentiated cells differentiate and become specialized
in their structure and function. These different cell types form specialized tissues that work in concert to perform all of the
functions necessary for the living organism. Cellular and developmental biologists study how the continued division of a
single cell leads to such complexity and differentiation.
CHAPTER 3 | THE CELLULAR LEVEL OF ORGANIZATION 87
Download for free at .
"The Cellular Level of Organization" from Anatomy and Physiology by OpenStax College is available under a
Creative Commons Attribution 3.0 Unported license. © 2013, Rice University.

Consider the difference between a structural cell in the skin and a nerve cell. A structural skin cell may be shaped like
a flat plate (squamous) and live only for a short time before it is shed and replaced. Packed tightly into rows and sheets,
the squamous skin cells provide a protective barrier for the cells and tissues that lie beneath. A nerve cell, on the other
hand, may be shaped something like a star, sending out long processes up to a meter in length and may live for the entire
lifetime of the organism. With their long winding appendages, nerve cells can communicate with one another and with other
types of body cells and send rapid signals that inform the organism about its environment and allow it to interact with that
environment. These differences illustrate one very important theme that is consistent at all organizational levels of biology:
the form of a structure is optimally suited to perform particular functions assigned to that structure. Keep this theme in mind