Domains of Life PDF

Domains of Life v Cell Theory: Cells are the basic unit of life All living things are composed of at least one cell and all cells come from preexisting cells. Single Cellular Organisms: made up of only one cell Multicellular Organisms: made up of many cells Single cellular organisms can cooperate in...

Domains of Life v Cell Theory: Cells are the basic unit of life All living things are composed of at least one cell and all cells come from preexisting cells. Single Cellular Organisms: made up of only one cell Multicellular Organisms: made up of many cells Single cellular organisms can cooperate in communities v Cells must exist and survive in many different environments Variable temperature Limited nutrients Toxic molecules Contact and communicate with other cells (tissues) Limited oxygen High pH Features found in all cells: Barrier between cell and environment Genetic material (DNA) Ribosomes Cytoplasm Features that differ between cell types: The type/composition of the barrier between cell and environment How they organize and store their genetic material The specific types of organelles and structures they contain Organisms can be described based on the way the access and create energy Autotrophs: Organisms that create their own energy from non-living materials (photosynthesis, chemosynthesis) Heterotrophs: Organisms that consume other organisms for energy Aerobes: Use oxygen in their metabolism Anaerobes: Do not use oxygen in their metabolism Life is organized into three domains 1. 2. 3. Bacteria Archaea Eukarya Prokaryotes Two domains: Bacteria and Archaea Characteristics of Prokaryotes: Single cellular organisms Lack a membrane bound nucleus and other membrane-bound organelles “pro” = before “karyote” = nucleus Prokaryotes are found in all environments Air, soil, water In extreme environments (hot springs, high salt concentrations, hydrothermal vents) Many prokaryotes live within other living organisms Pathogens/Parasites: detrimental to host organism Commensals: neutral to host organism Symbiotes/Mutualists: beneficial to host organism 2 Bacteria vs Archaea Typically differ based on the environments in which they are found Bacteria are typically found a variety of ‘normal’ environments Archaea are typically found in extreme environments There are several differences at the cell/molecular level as well. Prokaryotic Cells are Relatively Simple Cytoplasm Ribosomes Genetic Material is their nucleoid Barrier to the environment: -Plasma membrane -Cell wall -Additional structures often found in bacteria (capsule, fimbri, etc) Genetic Material in Prokaryotic cells Nucleoid: - A single, circular chromosomes - Contains all the genes required for survival and growth of the prokaryote Plasmids: - Small circular DNA elements - Not essential for life in most conditions, but often contain beneficial genes 3 Prokaryotes Two domains: Bacteria and Archaea Types of bacteria: Gram Positive Gram Negative Types of archaea: Haloarchaea Thermoacidophiles Methanogens Bacteria vs Archaea Typically differ in the environments where they are found -Bacteria are often found a variety of ‘normal’ environments -Archaea are often found in extreme environments Bacteria vs Archaea: Lipid Divide Archaea and bacteria differ based on the structure of the lipids that make up their cell membrane. Differences include: Types of chemical linkages and chirality in the head group of the lipids Different types of lipid forming the hydrophobic tails Bacteria vs Archaea: Cell Walls Bacteria have cells walls that include peptidoglycan Archaea have cell walls made of other types of proteins and/or sugars Types of Archaea Halophiles: live in high salt concentrations Thermoacidophiles: live in extreme temperatures and/or acidic conditions Methanogens: live in anaerobic conditions, use H2 to produce methane Archaea often require their preferred extreme environment to survive. Eukaryotes One domains: Eukarya Characteristics of Eukaryotes: Single or Multicellular organisms Have a membrane bound nucleus and other membrane-bound organelles “eu” = true “karyote” = nucleus Traditionally: Four Kingdoms within Domain Eukarya Plants - All multicellular - Autotrophs/Use photosynthesis Fungi - Some single celled (yeast), most multicellular - Heterotrophs Animals - All multicellular - Heterotrophs Protists: - Highly diverse - Many single cellular and multicellular organisms - Most ancient organisms of Eukarya DNA sequencing reveals 24 Eukaryotic Kingdoms Plant, Animal, Fungi Kingdoms confirmed Former Protist Kingdoms split into 21 new Kingdoms Animals, Plants, and Fungi are more closely related to Protists Kingdoms than to each other 6 Eukaryotic Organelles 24 Eukaryotic Kingdoms Kingdom Plantae Kingdom Animalia Kingdom Fungi 21 kingdoms of protists Organisms in all kingdoms have cells with membrane bound organelles Characteristics of a Eukaryotic Cell Ribosomes and Cytoplasm External Barrier: -Cell membrane -Cell wall in some cases DNA genome -in a membrane bound organelle called the nucleus -Multiple linear chromosomes Many other types of membrane-bound organelles Eukaryotic Genomes DNA is stored in the nucleus DNA is found as Multiple linear chromosomes Each chromosomes contains a different set of genes Eukaryotes Have Many Other Membrane Bound Organelles Structures created/surrounded by a single or double phospholipid bilayer Mitochondria Chloroplasts Endoplasmic Reticulum Golgi Apparatus “The –somes” Mitochondria and chloroplasts have features of prokaryotic cells Circular DNA Own Ribosomes Double membrane Endosymbiotic Theory The idea that some eukaryotic organelles arose from symbiotic interactions between eukaryotic cells and engulfed prokaryotes.