Chapter 6. Cell Structure and Function
Ayda Basgul Martin
Unit Outline
Part 1. Characteristics of Life
- Organization
- Metabolism
- Exchange of Material
- Responsiveness
- Movement
- Development, Growth, and Reproduction
Part 2. Structural Organization of the Body
Part 3. Cell Structure, Cellular Organelles, and Functions
- General Cell Structure: Plasma Membrane, Cytoplasm and Nucleus
- Organelles of the Endomembrane System
- Organelles for Energy Pocessing
Learning Objectives
At the end of this unit, you should be able to:
I. Specify the characteristics associated with life and explain why the cell is the basic unit of life.
II. Describe the levels of structural organization in the body.
III. Describe the structure and the functions of the major components of a cell.
IV. Define metabolism and distinguish between anabolism and catabolism.
V. Describe the cellular processes involved in the growth of the human body from a fertilized egg to an adult.
VI. Describe the importance of cell differentiation to an organism.
VII. Describe the general characteristics of each of the following cell types and relate their characteristics to their functions: nerve cell, muscle cell, red blood cell (erythrocyte), and white blood cell (leukocyte).
Part 1: Characteristics of Life
The different organ systems each have different functions and therefore unique roles to perform in the body. These many functions can be summarized in terms of a few that we might consider definitive of human life: organization, metabolism, exchange of materials, responsiveness, movement, development, growth, and reproduction.
Organization
A human body consists of trillions of cells organized in a way that maintains distinct internal compartments. These compartments keep body cells separated from external environmental threats and keep the cells moist and nourished. They also separate internal body fluids from the countless microorganisms that grow on body surfaces, including the lining of certain tracts, or passageways. The intestinal tract, for example, is home to even more bacteria cells than the total of all human cells in the body, yet these bacteria are outside the body and cannot circulate freely inside the body.
Cells, for example, have a membrane (also referred to as the plasma membrane) that keeps the intracellular environment—the fluids and organelles—separate from the environment outside the cell (the extracellular environment). Blood vessels keep blood inside a closed system, and nerves and muscles are wrapped in tissue sheaths that separate them from surrounding structures. In the chest and abdomen, a variety of internal membranes keep major organs such as the lungs, heart, and kidneys protected and separate from others.
The body’s largest organ system is the integumentary system, which includes the skin and its associated structures, such as hair and nails. The surface tissue of the skin is a barrier that protects internal structures and fluids from potentially harmful mic