Chapter 1 Exploring Life: Introducing Biology

Life is Organized on Several Levels

Levels Biosphere Biosphere Ecosystem Ecosystem Community Community Population Population

Levels Organism Organism System System Organs Organs Tissues Tissues Cells – life starts here Cells – life starts here Organelles Organelles Molecules – DNA & genes Molecules – DNA & genes Atom Atom

Organizational Levels of Life A. Biosphere 1. Consists of all the parts of the planet that are inhabited by living things 2. Includes most regions of land; most bodies of water and the atmosphere to an altitude of several kilometers.

B. Ecosystems 1. An ecosystem is the community of living things in an area, along with the nonliving features of the environment that support the living community. a) Example: A forest (includes various types of trees and plants, animals, microscopic forms of life, soil, water, air, sunlight, etc.)

C. Organisms 1. Organisms are individual living things a) Examples: squirrels, insects D. Cells 1. Cells are life’s basic units of structure and function

E. DNA and Genes 1. DNA is the chemical responsible for inheritance a) A DNA molecule contains the instructions for a cell to make all the other molecules it needs to function 2. Genes are units of inherited information

The Diversity of Life A. Species 1. A species is a distinct form of life a) ~ 5,000 species of bacteria; ~8,600 species of birds; ~30,000 species of fishes; ~100,000 species of fungi; ~280,000 species of plants; and ~1,000,000 species of insects

Figure 1-6 A green iguana (Iguana iguana) shares many characteristics with other species of iguanas, but fewer with other reptiles such as snakes or alligators. As categories of organisms become broader, the organisms in the category are more diverse.

B. The 3 domains of Life 1. A domain is the broadest category for classifying life forms 2. There are 3 domains: Archaea, Bacteria, and Eukarya

3.The simplest cells are called Prokaryotes a. These cells DO NOT have a nucleus or membrane-bound organelles b. Archaea and Bacteria are examples

4. More complex cells are called Eukaryotes a. These cells DO have a nucleus and membrane-bound organelles b. Eukarya (plants, animals, & fungi) are examples

5. Unicellular Organisms - Living Organism Made Up Of One Cell a. Examples: Archaea and Bacteria 6. Multicellular Organisms - Living Organism Made Up Of Many, Specialized Cells b. Examples: Eukarya

All Living Things Share Common Characteristics 1. Basic Unit is the Cell 2. They Reproduce 3. All Based On Universal Genetic Code (DNA) 4. Grow & Develop

Common Characteristics 5. Obtain & Use Materials & Energy 6. Respond To Their Environment 7. Maintain A Stable Internal Environment 8. AS A GROUP, Living Things Evolve, That Is They Change Over Time

All Organisms are made of Cells

Facts About Cells Cells are the smallest living unit of an organism All cells contain living material called cytoplasm All cells are surrounded by a cell membrane that controls what enters & leaves the cell

More Cell Facts Cells are complex & highly organized Cells have parts called organelles that do different jobs e.g. Chloroplasts in plants make sugars

Organisms Reproduce to Pass on their Genetic Traits

Two Types of Reproduction Sexual Reproduction Involves 2 parents Egg fertilized by sperm to make a ZYGOTE Offspring DIFFERENT from parents

Two Types of Reproduction Asexual Reproduction Involves a single organism or cell Cell divides Offspring IDENTICAL to parent

Living things have a Genetic Code

Genetic Code DNA (deoxyribose nucleic acid) carries the genetic code for all organisms All organisms contain DNA DNA codes for the proteins that make up cells & do all the work

Organisms Grow & Develop

Growth & Development Cells grow by producing MORE CELLS & by cell ENLARGEMENT Organisms develop as they mature into an adult organism

Cells Require Food & Energy

Food Requirements Producers can make their own food Consumers consume food made by producers Sun is the ultimate source of energy

Organisms Respond to Environment Organisms Respond to Temperature, Water, Food Supplies, etc. In Order To Survive & Reproduce

Homeostasis Keeping The Internal Environment Of The Cell or Organism Within The Ranges Required For Life Stable internal conditions of pH, temperature, water balance, etc.

Living Things Evolve Groups Of Organisms (Not Individuals) Change Over Time In Order To Survive Within Changing Environments. Fossil records show changes in groups of organisms