4 Chapter 4: Cell Structure and Transport
Chapter Outline
- 4.1 Studying Cells
- 4.2 Prokaryotic Cells
- 4.3 Eurkaryotic Cells
- 4.4 The Endomembrane System and Proteins
- 4.5 The Cytoskeleton
- 4.6 Connections between Cells and Cellular Activities
- 4.7 Plasma Membrane Components and Structure
- 4.8 Passive Transport
- 4.9 Active Transport
- 4.10 Bulk Transport
Close your eyes and picture a brick wall. What is the basic building block of that wall? A single brick, of course. Like a brick wall, your body is composed of basic building blocks, and the building blocks of your body are cells. Your body has many kinds of cells, each specialized for a specific purpose. Just as a home is made from a variety of building materials, the human body is constructed from many cell types. For example, epithelial cells protect the surface of the body and cover the organs and body cavities within. Bone cells help to support and protect the body. Cells of the immune system fight invading bacteria. Additionally, blood and blood cells carry nutrients and oxygen throughout the body while removing carbon dioxide. Each of these cell types plays a vital role during the growth, development, and day-to-day maintenance of the body. In spite of their enormous variety, however, cells from all organisms—even ones as diverse as bacteria, onion, and human—share certain fundamental characteristics.
Figure 4.1 (a) Nasal sinus cells (viewed with a light microscope), (b) onion cells (viewed with a light microscope), and (c) Vibrio tasmaniensis bacterial cells (seen through a scanning electron microscope) are from very different organisms, yet all share certain characteristics of basic cell structure. (credit a: modification of work by Ed Uthman, MD; credit b: modification of work by Umberto Salvagnin; credit c: modification of work by Anthony D’Onofrio, William H. Fowle, Eric J. Stewart, and Kim Lewis of the Lewis Lab at Northeastern University; scale-bar data from Matt Russell)
Learning Objectives
You will be able to describe the basics of cells:
- Identify major cell components
- Differentiate the functions of cell part
- Be able to describe these characteristics of cellular transport:
- compare and contrast the different forms of membrane transport
- diffusion
- passive transport
- active transport
- vesicular transport
4.1 | Studying Cells
A cell is the smallest unit of a living thing. A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism. Several cells of one kind that interconnect with each other and perform a shared function form tissues, several tissues combine to form an organ (your stomach, heart, or brain), and several organs make up an organ system (such as the digestive system, circulatory system, or nervous system). Several systems that function together form an organism (like a human being). Here, we will examine the structure and function of cells. There are many types of cells, all grouped into one of two broa