1. Biology and You
Chapter 1

2. Overview
The purpose of this chapter is to introduce you to characteristics shared by all living organisms, including yourselves. During your study of this chapter, you will learn how your own lives relate to the study of biology, and how biologists approach the study of living organisms. These themes will recur throughout the course. 1

3. Section 1: Themes of Biology

4. Section 1 Objectives
Relate the seven properties of life to a living organism.
Describe seven themes that can help you organize what you learn about biology.
Identify the tiny structures that make up all living things.
Differentiate between reproduction and heredity and between metabolism and homeostasis. 1

5. Characteristics of Living Organisms
The photo at the right shows an orphaned rabbit.
Imagine that you are holding and feeding the rabbit.
How do you know that it is alive?
What does the rabbit need to stay alive? 1

6. Characteristics of Living Organisms
[Organism = living thing]
Defining life is difficult, many nonliving things display some characteristics of life.
[Biology = the study of life]
All living things share certain general properties that separate them from nonliving things.

7. Characteristics of Living Organisms
PROPERTIES OF LIFE
Cellular organization
Reproduction
Metabolism
Homeostasis
Heredity
Responsiveness
Growth and development

8. Characteristics of Living Organisms
Cellular organization - every living thing is composed of one or more cells
Reproduction - all living things are able to reproduce
Metabolism - all obtain and use energy to run the processes of life
Homeostasis - living organisms maintain a consistent internal environment
Heredity - living things pass traits to offspring
Responsiveness - all living things respond and adjust to the environment
Growth and development - all living things grow and develop

9. Unifying Themes in Biology
In the study of Biology, broad themes emerge that:
Unify living things – explain the similarities among organisms despite their great diversity.
Explain Biology as a science, a systematic process of inquiry

10. Unifying Themes in Biology
The themes include:
Cellular structure and function
Reproduction
Metabolism
Homeostasis
Heredity
Evolution
Interdependence

11. Unifying Themes in Biology
Theme #1--Cellular structure and function
All living things are made of one or more cells.
Cells are the smallest units capable of all life functions.

12. Unifying Themes in Biology
Theme #2—Reproduction
Reproduction = the process by which organisms make more of their own kind.
All living things reproduce.
Though life spans vary, no organism lives forever.

13. Unifying Themes in Biology
Theme #3—Metabolism
Metabolism is the sum of all chemical reactions carried out in an organism.
These chemical reactions occur in order to obtain and use energy for all life processes (growth, movement, etc.)

14. Unifying Themes in Biology
Energy flow
Energy is captured from sunlight by plants, algae, and some bacteria through photosynthesis
This energy is used to build complex molecules.
Complex molecules serve as sources of energy (food) for other organisms

15. Unifying Themes in Biology
Theme #4—Homeostasis
Refers to the maintenance of stable
internal conditions regardless of external change.
All organisms must be able to maintain stable internal environment in order to function properly.
Example: Mammals maintain a fairly constant body temperature regardless of the environment

16. Unifying Themes in Biology
Theme #5—Heredity
Refers to the ability to pass traits from parent(s) to offspring each generation.
The basic units of heredity are the genes, coded segments of a deoxyribonucleic acid (DNA) molecule.
Mutation is change in the DNA of a gene
Only mutations that occur in sex cells (egg, sperm) are passed on
Most mutations that cause change are harmful, but some are beneficial

17. Unifying Themes in Biology
Theme #5—Heredity (cont.)
Examples of mutations
Sickle-cell disease
Affects hemoglobin, the oxygen transporting protein in red blood cells.
Causes red blood cells to become distorted into irregular shapes that do not travel through tiny capillaries.
A positive effect of the mutation is resistance to Malaria
Cancer may result from mutations in body cells that disrupt the control of cell reproduction.

18. Unifying Themes in Biology
Theme #6—Evolution
Refers to change in the inherited
characteristics of species over
generations.
[species = a group of genetically similar organisms that can interbreed and produce fertile offspring]
Occurs by the process of natural selection
Provides a consistent explanation of life’s diversity—it unifies all branches of biology. 2

19. Unifying Themes in Biology
Theme #7—Interdependence
Organisms live and interact with
other organisms.
Ecology is the study of interactions of
organisms with one another and with the
nonliving part of their environment.
Interdependence within biological communities is the result of a long history of evolutionary adjustments. 2

20. Review A change in the DNA of a gene is called a ____.
The many different species of organisms on Earth today are the result of _____.
The maintenance of a stable internal environment is called _____.
mutation
evolution
homeostasis 2