Bacteria, Archaea, & Protista Chapter 24

What you need to know! Different Domains of unicellar organisms How chloroplasts and mitochondria evolved through endosymbiosis Protista is no longer considered an independent kingdom. They are part of the Eukaryotes domain and are very diverse. How Chloroplasts and mitochondria evolved through endosymbiosis

Domains Bacteria Archaea Eukarya

Characteristics of Prokaryotes (both domains) No membrane bound organelles Smaller ribosomes Haploid (no meiosis) Can have plasmids (horizontal gene transfer) Can have flagella (made of flagellin not tubulin) Evolved all metabolic pathways on earth Photoautotroph, chemoautotroph, photoheterotroph, chemoheterotroph Classified based on: metabolism then shape then staining Cell walls (different molecular make-up) Reproduce via binary fission

Eubacteria Characteristics Identified by shape: cocci (sphere), bacilli (rod), spirilla (spirals) Distinguished by staining method Gram positive = outer cell wall Gram negative = inter cell wall (between 2 membranes) Cyanobacteria (formerly blue/green algae): photosynthetic, some fix nitrogen Chemosynthetic bacteria: autotrophs, some fix nitrogen Nitrogen Fixing Bacteria: heterotrophs, mutualistic with plants, live in modules Endospores: DNA packed into cell wall for long term hybernation/survival

Types of Archaeabacteria Methanogens: anaerobic, chemoheterotrophic (obligate anaerobes), produce methane; found in: deep-sea hydrothermal vents, mud, swamps, guts of cows, and termites Extremophiles: Extreme Halophiles: aerobic, heterotrophic, or anaerobic, photosynthetic (with pigments), live in high salinity (Salt Lake, Dead Sea) Extreme Thermophiles: chemosynthesis, autotrophs, live in high heat (150 – 180 degrees F)

Horizontal Gene Transfer A process in which genes are transferred from one genome to another by methods other than reproduction: Transformation: uptake of foreign DNA Viral infection Transduction: viruses (accidentally) transfer non viral genes from their maker to their host Conjugation: Exchange of transposable elements (plasmids) from source to target Fusions of organisms endosymbiotic hypothesis

Protista ≠ Kingdom

Characteristics Protists are eukaryotes Can be unicellular, colonial or multicellular Predecessor to other eukaryotes: plants, fungi, and animals. Eukaryotic fossils date back 1.8 billion years Some of the most complex cell structures found Special organelles: contractile organelle (primitive excretion, H20 balance), eye spots (primitive sight), anal pores (primitive waste excretion)

Endosymbiotic Hypothesis

Metabolism Protists are the most nutritionally diverse of all eukaryotes: Most protists are aerobic, with mitochondria for cellular respiration. Some protists are photoautotrophs with chloroplasts. Still others are heterotrophs that absorb organic molecules or ingest larger food particles. A few are mixotrophs (heteroautotrophs), combining photosynthesis and heterotrophic nutrition

Specifics Absorptive, protists (fungus-like) Protozoa - ingestive, animal-like protists Algae - photosynthetic, plant-like protists. Features: Flagella: Protists have a flagella or cilia during some time in their life cycles. The eukaryotic flagella are extensions of the cytoplasm with a support of a microtubule system (made from tubullin) Cilia are shorter and more numerous than flagella.

Reproduction protists can reproduce asexually or sexually Many protists form resistant cells (cysts) that can survive harsh conditions. Protists are the first group to show “alternation of generation”: Most protists are haploid organisms (n), called gametophytes Gametophytes produce gametes Gametes fuse to form a zygote The Zygote develops into a sporophyte (not the main organisms) The Sporophyte produces haploid spores that germinate into gametophytes

Habitat Protists are found almost anywhere there is water: Oceans, ponds, and lakes, but also damp soil, leaf litter, and other moist terrestrial habitats. Protists are also important parts of the plankton, communities of organisms that drift passively or swim weakly in the water. Phytoplankton (including planktonic eukaryotic algae and prokaryotic cyanobacteria) are the bases of most marine and freshwater food chains.

Lifestyle Many protists are symbiots that inhabit the body fluids, tissues, or cells of hosts. These symbiotic relationships span the continuum from mutualism to parasitism (malaria, giardia)

Euglena Part of phytoplankton mixotrophic Base of marine and fresh water food webs

Amoebas Pseudopods, extensions of the cytoplasm Capturing prey, locomotion Heterotrophic

Radiolarians Skeleton pseudopods to increase surface area

Foraminiferans Beautifully shaped calcium carbonate or silica shelled protists

Paramecium Coordinated movement through ciliates Complex organelles: contractile vacuole for osmoregulation (pumping out water)

Malaria (protozoan) transmitted by infected mosquito

Phylum Crysophyta/Diatoms Abundant in plankton and sediments Have silica shells Top and bottom shells fit together like boxes

Well Known Members Infamous: Giardia Trypanosomes Malaria Cute Paramecium Amoeba Mistaken as other organisms Brown, green, and red algae Giant Kelp

Critical Vocabulary Obligate aerobes: need oxygen environment to live Obligate anaerobes: need an oxygen free environment to live (absolutely no oxygen) Facultative anaerobes: can survive w/ or w/out oxygen