Characteristics of Life
January 12, 2004
Characteristics
of Life
January 12, 2004
Readings: Starr, pps. 2-11. Check out the Help page for Tips on N100!
"The most beautiful thing we can
experience is the mysterious. It is the source of all true art
and science".
-- Albert Einstein
Chapter 1 - What is Biology?
I. What is Biology? Biology is the study of life. It is a human endeavor that results from our attraction to life in all its forms (E.O. Wilson's biophilia.)
II. Why Study Biology?
Career - to become an MD, dentist, pharmacist, vetrinarian, research scientist or to become an Elementary School Teacher, Middle School or High School Science teacher.
Curiosity - the desire to understand or observe the living world
Technological Relevance - the need to understand and make decisions involving healthcare, the environment, food production and safety, that have a scientific as well as a social or ethical component.
III. What are the major
themes of Biology? These are the
Big Ideas that provide a framework for understanding most aspects
of biology:
1. Evolution by Natural Selection - Organisms most suited to their environment most likely to pass their traits onto subsequent generations. Evidence for evolutionary theory was first put forth when Charles Darwin published The Origin of Species in 1859 and today provides the framework for modern biological thought (Chapters 16-18).
2. Inheritance - All living organisms possess a genetic system based on DNA, that specifies the information to make proteins, and is inherited by offspring (Chapters 10-13).
3. Cell Theory - The cell is the smallest unit of life, and all living organisms are composed of one or more cells (Chapter 1, 4).
4. Classification of Life - Life can be categorized by similarities in physical or anatomical form, and by relatedness in the DNA and RNA between species (Chapter 19-28).
5. Bioenergetics - Cellular metabolism is based on chemical reactions occur in cells that follow the laws of the physical sciences (Chapter 6-7).
6. Homeostasis - Organisms function best when their internal environment is kept relatively constant, and have mechanisms to maintain a 'steady state' within their cells (Chapter 3, 5).
7. Ecosystems - Organisms, including humans, interact with each other and with their environments (Chapters 43-45).
IV. What is Life?
Life: 'The property manifested in functions such as metabolism, growth, response to stimulation, and reproduction, by which living organisms are distinguished from dead organisms or from inanimate matter.' (Webster's Dictionary)
Life: 'The state of being which begins with generation, birth, or germination, and ends with death; also, the time during which this state continues; that state of an animal or plant in which all or any of its organs are capable of performing all or any of their functions; used of all animal and vegetable organisms.' (Gray's Medical Dictionary)
Life: As described in the Catholic Encyclopedia - for those interested in a more philosophical definition...
V. What Properties are Associated with Life? Life is difficult to define, but all living organisms are alike in these aspects:
1. Cellular Organization: All living organisms are composed of one or more cells - the basic unit of life ... "Life is Totally Cellular"
2. Heredity: All living organisms possess a genetic system based on the replication of DNA (or a related molecule, RNA), that specifies the information to make cellular proteins.
3. Growth and Development: All living organisms assemble matter (chemical elements) into simple or complex compounds, and use the energy derived from these compounds to grow and change over time. The process of using chemical energy to do cellular work is called metabolism.
4. Reproduction: All living organisms are programmed to produce new generations of cells or new multicellular organisms similar to themselves.
5. Response to Environment: All living organisms sense changes in their surroundings (using receptors), make controlled responses (behavior), and keep their internal environment relatively constant (homeostasis).
Worksheet: Are viruses alive?
VI. Life is organized on many structural levels: At each level of organization, novel properties emerge that were not present at the previous level.
Objectives - Ch 1: Characteristics of Life. Be sure you are able to
1. Explain the major themes of biology
2. List characteristics that distinguish living organisms from non living objects
3. List the levels of chemical / biological organization from simple to complex, and list a structure found at each level