Chapter 1Chapter 1

Exploring Life:Exploring Life:

Introducing Introducing BiologyBiology

Life is Organized on Life is Organized on Several LevelsSeveral Levels

LevelsLevels

BiosphereBiosphere EcosystemEcosystem CommunityCommunity PopulationPopulation

LevelsLevels OrganismOrganism SystemSystem OrgansOrgans TissuesTissues CellsCells – life starts here – life starts here OrganellesOrganelles Molecules – DNA & genesMolecules – DNA & genes AtomAtom

Organizational Levels of LifeOrganizational Levels of Life

A. BiosphereA. Biosphere1. Consists of all the parts 1. Consists of all the parts

of of the planet that are the planet that are inhabited inhabited by living thingsby living things

2. Includes most regions of 2. Includes most regions of land; most bodies of land; most bodies of

water and water and the atmosphere the atmosphere to an altitude to an altitude of several of several kilometerskilometers..

B. EcosystemsB. Ecosystems1. An ecosystem is the 1. An ecosystem is the

community community of living things in of living things in an area, along an area, along with the with the nonliving features of the nonliving features of the environment that support the environment that support the living living community.community.

a) Example: A forest a) Example: A forest (includes various types of (includes various types of

trees trees and plants, animals, and plants, animals, microscopic microscopic forms of life, forms of life, soil, water, air, soil, water, air, sunlight, sunlight, etc.)etc.)

C. OrganismsC. Organisms

1. Organisms are individual 1. Organisms are individual living living thingsthings

a) Examples: squirrels, a) Examples: squirrels, insectsinsects

D. CellsD. Cells

1. Cells are life’s basic units of 1. Cells are life’s basic units of structure and functionstructure and function

E. DNA and GenesE. DNA and Genes

1. DNA is the chemical 1. DNA is the chemical responsible responsible for for inheritanceinheritance

a) A DNA molecule contains a) A DNA molecule contains the the instructions for a cell to instructions for a cell to make make all the other all the other molecules it needs molecules it needs to to functionfunction

2. Genes are units of inherited 2. Genes are units of inherited informationinformation

The Diversity of LifeThe Diversity of LifeA. SpeciesA. Species

1. A species is a distinct form 1. A species is a distinct form of lifeof life

a) ~ 5,000 species of a) ~ 5,000 species of bacteria; ~8,600 bacteria; ~8,600

species of species of birds; ~30,000 birds; ~30,000 species of species of fishes; fishes; ~100,000 species of ~100,000 species of fungi; fungi; ~280,000 species of ~280,000 species of plants; plants; and ~1,000,000 and ~1,000,000 species of insectsspecies of insects

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

B. The 3 domains of LifeB. The 3 domains of Life1. A domain is the broadest 1. A domain is the broadest category for classifying life category for classifying life

formsforms

2. There are 3 domains: 2. There are 3 domains: Archaea, Bacteria, and Archaea, Bacteria, and

EukaryaEukarya

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 Cella. Examples: Archaea and Bacteria

6. Multicellular Organisms - Living Organism Made Up Of Many, Specialized Cellsb. Examples: Eukarya

All Living Things Share All Living Things Share Common Common

CharacteristicsCharacteristics1.1. Basic Unit is the CellBasic Unit is the Cell

2.2. They ReproduceThey Reproduce

3.3. All Based On Universal All Based On Universal Genetic Code (DNA)Genetic Code (DNA)

4.4. Grow & DevelopGrow & Develop

Common Common CharacteristicsCharacteristics

5.5. Obtain & Use Materials & Obtain & Use Materials & EnergyEnergy

6.6. Respond To Their Respond To Their EnvironmentEnvironment

7.7. Maintain A Stable Internal Maintain A Stable Internal EnvironmentEnvironment

8.8. AS A GROUP, Living Things AS A GROUP, Living Things Evolve, That Is They Change Evolve, That Is They Change Over TimeOver 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