Classification Systems Change as Scientists Learn More

1. Classification Systems Change as Scientists Learn More • Taxonomy Changes as Scientists make Discoveries. • 3 Domains & 6 Kingdoms • The 2 most Familiar Kingdoms are Plants & Animals • Other Organisms make up 4 More Kingdoms • Mushrooms & Molds (which Linnaeus put as plants) are now classified as FUNGI • Other kingdoms are PROTISTA, ARCHAEA & BACTERIA • Species & Environment Changes • Scientist estimate there are millions or tens of millions of undiscovered species. Species may change somewhat as their environment changes over time.

2. 3 DOMAINS • Microscopes have let scientists observe 3 different types of cells; so they have arranged the 6 kingdoms into 3 groups (DOMAINS) based on this. • Eukarya includes protists, fungi, plants & animals (all have a nucleus, so are eukaryotes) • Bacteria and Archaea have no nucleus (PROKARYOTE cells). Archaea have a unique chemistry and can survive extreme environments.

3. 6 KINGDOMS • Kingdom Plantae: plants; trees, grass & moss • Kingdom Animalia: animals; lions & bears to bugs & multicellular microbes. • Kingdom Protista: mostly unicellular organisms with nucleus • Kingdom Fungi: mushrooms, molds, & yeasts • Kingdom Archaea: similar to bacteria, but very unique cell structure • Kingdom Bacteria: unicellur organisms with no nucleus • This system may change as we learn more

4. About 250,000 plant species live on Earth. (tiny mosses to giant sequoia trees) Oldest plant = bristelcone pine -over 4,000 years old All plants are multicellular eukaryotes (nucleus). All can make sugar from Sun’s Energy, can’t move around except by growing upward & toward light. Plant cells differ from animal cells by having tough walls outside of cell membrane. Scientists already named a million species of animals. More than 90% are insects, but also whales, sharks, humans, bears, dogs, fish. All animals get energy by eating other organisms or by eating food made by other organisms. Have ability to move around for at least part of life. Most animals have mouths & nervous system. Are eukaryotes (like plants) but have no cell walls. Plantae & Animalia Kingdoms

5. PROTISTA • Includes wide variety of organisms (many scientists think this should be split into more kingdoms) • Most are unicellular, some are multicellular but too simple to be fungi/animal or plants. • All have large, complex cells with nucleus (eukaryote); some eat other organisms, some get energy from sun (like plants); no specialized cells or structures • Many live in pond/sea water; many microscopic, but seaweed is a very large protist (may grow hundreds of feet/year)

6. FUNGI • One group of fungus, YEAST, lets bread rise. Another that people eat are MUSHROOMS. These grow in thin threads underground & only the small cap breaks above the ground. • Usually 3 groups: mushroom, yeast, & molds. Fungi take in nutrients from their surroundings instead of eating or using sunlight. • Stay rooted in 1 place (like plants), most have cell walls too. • Many act as decomposers (break down dead/decaying material into simpler parts that can be absorbed or recycled by other organisms.

7. ARCHAEA • In mid-’90’s a scientist studied genes of some bacteria and found some had very different genes. These bacteria were called archaea, and are now known to be so different, they are in their own kingdom & domain. • Archaea have no nucleus & live in many environments (like bacteria) but cell structure is different than bacteria. • Some live in very extreme environments (boiling mud near gysers, hot vents on ocean floor, salty ponds, & deep under sand.

8. BACTERIA • Bacteria live nearly everywhere on Earth. Some cause human disease & spoil food, but most are helpful members of biological community. • All are unicellular. Small, simple cells without a nucleus(prokaryote). • Most have cell wall, but different from plant type. • Reproduce by dividing in 2 (binary fission/mitosis), and can make many new generations in very short time period.