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Download Chapter 5 Bacteria / Diatoms / Dinoflagellates
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Chapter 5 Bacteria: Diatoms / Dinoflagellates Bacteria • unicellular • small size (about 250,000 average-sized bacteria could fit on one period.) • simplest organisms • have a cell wall and cell membrane • no nucleus nor membrane bound organelles Two Domains • Bacteria are found in most places (soil, water, internally, any surface) • Archaea often found in extreme conditions (high temperatures, high salinity, extreme cold, no oxygen) Bacteria Identification by shape • bacillus (rod) Bacteria Identification by shape • coccus (sphere) Bacteria Identification by shape • spirilla (spiral) Bacteria Identification by shape • Ring • amorphic (shapeless) Bacteria Identification • can be identified using Gram stain • stain interacts with cell walls to color purple (positive) or pink (negative) Bacteria Features • flagella – Latin for “whip”; whip-like appendage that protrudes from the cell body and used for the propulsion or movement of the cell Bacteria Features • pilli – Latin for “hair”; hair-like appendage found on the surface of many bacteria used for the transfer of DNA between bacteria Bacteria Features • capsule –covering around cell wall; function is for protection or means of attachment DRAW BACTERIA CELL AND LABEL 3 MAIN PARTS Bacteria Importance • Beneficial (decomposition/recycling of nutrients; food chains; bioluminescence for animals) • Harmful (food poisoning; disease) Heterotrophic Bacteria • get energy by consuming others • consume organic matter, make up part of a food chain • some are decomposers that break down dead matter which is important for recycling nutrients Autotrophic Bacteria • bacteria that make their own energy (2 types: photosynthetic and chemosynthetic) • photosynthetic – uses sunlight • chemosynthetic – uses chemical compounds like hydrogen, ammonia, hydrogen sulfide Photosynthetic Bacteria (cyanobacteria) • “blue-green algae” • have chlorophyll like plants as well as phycocyanin (blue pigment) • among the oldest living things • thought to have added oxygen to the atmosphere Chemosynthetic Bacteria • were called “extremophiles” – lovers of the extreme • found along hydrothermal vents and can survive EXTREME temperatures • form part of the food chain and live inside animals like tube worms Diatoms • Eukaryotic single-celled photosynthetic algae • Divided into two major groups based on the structure and shape of the valves. (Centrics and Pennates) • do not propel themselves up and down in the water column, but are dependent on oceanic currents for transport Diatoms • The presence of chlorophyll and accessory pigments give them a golden color and serves to harvest light energy from the sun Diatoms • Cells are encased in transparent glass-like (silica) “container” called a frustule that resembles a petri-dish. • The frustules can be ornate and very beautiful, and due to the resistance of silica, they form an important part of the fossil record Diatoms • Cells may form chains or colonies and may have distinctive shapes or structures which help them stay afloat. • Up to 100,000 species of diatoms have been recorded world-wide. Dinoflagellates • Eukaryotic singlecelled algae • Many have two flagella, which allow the cells to have limited mobility • Cells are covered by a theca (sheath) that can be smooth or ornamented Dinoflagellates • Some species are able to migrate vertically through the water column (vertical migration), seeking nutrients, prey, or protection from harmful UV rays. Dinoflagellates • Nearly half of known species are capable of photosynthesis and contain light-harvesting pigments (autotrophs) • Some species survive by other nutritional modes, and may absorb organic matter or engulf prey (heterotrophs) Dinoflagellates • Of the 2000 known species, about 60 are able to produce complex toxins
