Properties of Life and Classification of Organisms

Organism:

Any living thing that possesses or once had all the characteristics that define life.

Key Characteristics of Living Organisms:

Order

Organized structure.

Response to Environment:

Detect and respond to stimuli.

Reproduction:

Ability to produce new organisms (Sexual or Asexual).

Adaptation:

Change over time to survive in environments.

Growth and Development:

Cells divide and organisms grow

Cells:

All living things are made of one or more cells.

Regulation & Homeostasis

• Maintain stable internal conditions (temperature, pH).

Energy Processing:

Acquiring energy (food chain, food web)

Evolution:

Change in characteristics of populations over generations.

Response to Environment (Stimulus Response)

Stimulus:

A change in the internal or external environment.

Response

Reaction of an organism to a stimulus.

Energy Consumption and Release

Autotrophs:

Organisms (e.g., plants) that produce their own energy via photosynthesis.

Heterotrophs

• Organisms (e.g., animals) that consume other organisms for energy.

Cell Theory Components

All organisms are made up of one or more cells.

The cell is the basic unit of structure and function in organisms.

Cells arise from pre-existing cells.

Regulation and Homeostasis

Maintaining a stable internal environment (e.g., temperature, pH).

Adaptations

• Changes in characteristics of populations over time in response to environmental pressures.

• Example: Charles Darwin's theory of natural selection.

Prokaryotes vs. Eukaryotes

Prokaryotes:

• Single-celled organisms without membrane-bound nuclei.

• No histones, no chromosomes.

• Have a cell wall, plasma membrane, cytoplasm, ribosomes.

• Examples: Bacteria, Archaea, Cyanobacteria.

Eukaryotes:

• Multicellular organisms with membrane-bound organelles and a nucleus.

• Contain histones and chromosomes.

• Examples: Protists, Fungi, Plants, Animals.

Reproduction

Sexual Reproduction:

Genetic material from two parents creates non-identical offspring.

Asexual Reproduction

• Single parent produces genetically identical offspring.

Methods of Asexual Reproduction:

1. Binary Fission: A parent cell splits into two identical daughter cells.

2. Fragmentation: A parent organism breaks into pieces, each developing into a new organism (e.g., starfish).

3. Budding: A new organism forms from a bud on the parent cell (e.g., yeast).

Levels of Classification (Taxonomy)

Domain: Highest classification level. Three domains:

1. Bacteria: Prokaryotes, unicellular, no nucleus, found in various environments.

2. Archaea: Prokaryotes, unicellular, no nucleus, found in extreme environments.

3. Eukarya: Eukaryotes, uni/multicellular, contain a nucleus.

Kingdoms of Eukarya

• Protists:

  • Mostly unicellular.

  • Prefer aquatic or moist environments.

  • Move using flagella, cilia, or pseudopods.

  • Examples: Algae, amoebas.

Kingdoms of Eukarya

• Fungi:

  • Multicellular.

  • Decomposers; obtain food from other sources.

  • Cell walls made of chitin.

  • Examples: Yeast, molds, mushrooms.

Kingdoms of Eukarya

Plants (Plantae):

• Multicellular autotrophs.

• Perform photosynthesis using chloroplasts.

• Cell walls made of cellulose.

• Examples: Mosses, ferns, trees.

Kingdoms of Eukarya

Animals (Animalia):

• Multicellular heterotrophs.

• Lack cell walls.

• Obtain nutrients by consuming other living things.

• Examples: Insects, mammals, birds.

Summary of Domains and Kingdoms

Domains: Bacteria, Archaea, Eukarya.

• Kingdoms within Eukarya: Protists, Fungi, Plants, Animals.

Monophyletic

Single tribe

Includes the ancestor and all its descendants