Unit 4: Unit 4: Classification of Living Classification of Living

ThingsThings

Characteristics of Living Things

• All living things:1. Have Cellular

Organization2. Share Chemicals of Life3. Need Energy4. Respond to

Surroundings5. Grow and Develop6. Reproduce

Cellular Organization

• Cell- The basic unit of structure and function in an organism • Unicellular- single celled • Multicellular- many cells

Chemicals of Life

• Carbohydrates- also called sugars, used for energy • Proteins- building material of cells • Lipids- building material of cells • Nucleic Acids- genetic material,

gives cell instructions and controls cell’s activities

Energy Use

• Cells need energy to function and repair themselves!

• The sun is the ultimate source of energy for all life on earth.

Response to Surroundings

• Stimulus- a change that causes an organism to react (ex: temp, light, sound) • Response- an action or change in behavior…happens because of

stimulus

Growth, Development, Reproduction

• Growth- getting larger

• Development- becoming more complex

• Reproduction- passing on genetic material

Life Comes From Life

• Spontaneous Generation- living things can arise from

nonliving things- HAS BEEN DISPROVEN

• It took hundreds of years and lots of experiments to prove this

Life Comes From Life• Francesco Redi

designed one of the first controlled experiments. In his experiment, Redi showed that flies do not spontaneously arise from decaying meat.

Life Comes From Life

• Louis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria.

The Needs of Living Things

1. Water- can only live a few days without water. Need it to

obtain chemicals, digest, grow, move, and reproduce 2. Food- Used for energy source

a. Autotrophs- Make their own energy using sunlight (plants)

 b. Heterotrophs- Obtain food

by eating other organisms

3. Living Space- organisms compete for space and resources

4. Stable Internal Conditionsa. Homeostasis- maintaining

stable internal conditions so cells can properly function (our body temp)

The Needs of Living Things

• Scientists classify so we can make sense of the world and living things, makes living things easier to study. • Classification- the process of grouping things based on their similarities • Taxonomy- the scientific study of

how living things are classified

Classification

• Binomial Nomenclature- Created by Linneaeus, 2-part naming system.

Uses Genus and Species. Ex: Homo sapiens • Genus- contains similar, closely-related organisms. Pumas and house cats are in Genus Felis. They have sharp, retractable claws, and hunt. • Species- group of similar organisms that can mate with each other and produce viable offspring

Classification

Levels of Classification- The more levels that 2 organisms share, the more

characteristics they have in common

KingdomPhylumClassOrderFamilyGenusSpecies

Classification

• As you move down the levels of classification, the number of organisms decreases. The organisms at lower levels share more characteristics with each other.

Levels of Classification

• Prokaryotes- Don’t have a nucleus • Eukaryotes- have a nucleus • Autotrophs- Make food from sun • Heterotrophs- obtain food from

eating autotrophs and other heterotrophs

Terms

Cell Wall- rigid layer of material that surrounds some cells to provide protection & support(plants, fungi, bacteria)

animal

plant

bacteria

No cell wall

Three Domains of Life

In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.

Three Domains of LifeBacteria

(Prokaryotes, Autotrophs &

Heterotrophs, Cell Walls)

Kingdom: EubacteriaOn your body, in foods we eat. Most aren’t harmful.

Archaea(Prokaryotes, Autotrophs

& Heterotrophs, Cell Walls)

Kingdom: ArchaebacteriaLive in extreme environments (dark, hot, salty, etc). Archaea means “ancient” in Greek.

Eukarya(Eukaryotes)

Kingdoms:Protists- Can’t be classified as anything else. Very Diverse. (NO Cell Walls) Auto/heterotrophs, uni/multicellular. Seaweed, Paramecium

Fungi- Mushrooms, molds, mildew. Most are multicellular. Heterotrophs. (Cell Walls) Absorb nutrients from decaying organisms.

Plants- trees, moss, peas. Multicellular. (Cell Walls) Most live on land. Autotrophs. Very diverse.

Animals- Multicellular. Heterotrophs. (NO Cell Walls) Very diverse.

• Keys are used to determine the identification of organisms.• Statements are in pairs

Taxonomic (Dichotomous) Key