Prokaryotes and “Kingdom Protista”

Domain bacteria Domain Archae The Prokaryotes

Cell type: Prokaryotes Found in: – Domain Bacteria – Domain Archaebacteria

Cell type: Prokaryotes Two Domains: Bacteria and Archae Do not have a membrane bound nucleus Very few organelles, if any Smallest and structurally simplest living organisms. Oldest forms of life on earth Microscopic Circular shaped DNA molecules Shapes: rod, spherical or spiral

Metabolism Autotrophic -photosynthetic -chemosynthetic Heterotrophic -aerobic respiration (with oxygen) -anaerobic respiration (without oxygen) ex: use SO 4 -2 instead of oxygen (Anoxic: environment without oxygen)

Domain Bacteria Unicellular; some form colonies. Cell wall of peptidoglycan Essential role in nutrient cycles Major groups: decay bacteria, cyanobacteria, nitrifying bacteria, pathogenic bacteria

Domain Bacteria: Decay Bacteria Break down waste products and detritus Detritus: dead organic matter Release nutrients into the environment Importance: recycling of essential nutrients

Domain Bacteria: Cyanobacteria Also known as blue-green algae Photosynthetic Photosynthetic Pigments -Contains chlorophyll a (pigment in plants) -Phycocyanin: bluish pigment -Phycoerythrin: reddish pigment -Dominant pigment determines color

Domain Bacteria: Cyanobacteria Stromatolites: Thought to have an important role in the accumulation of oxygen in earth’s atmosphere Prochlorococcus: thought to be most abundant photosynthetic organism in the ocean Red tides: bloom of cyanobacteria with red pigment (can cause skin rashes)

Prochlorococcus

Oscillatoria

Spirulina and Oscillatoria

Anabaena

Domain Bacteria: Nitrifying Bacteria Carry out nitrogen fixation -converting nitrogen gas into ammonium which is then converted into nitrates.

Domain Archae Used to be classified with Bacteria but are now thought to be closer related to eukaryotes. Extremophiles: found in extreme environments (acid pools, hot springs, hydrothermal vents, etc…) Methanopyrus: methanogen living near hydrothermal vents Common throughout the ocean not just extreme environments

Domain Eukarya “Kingdom Protista” The Eukaryotes

Cell type: Eukaryotes Have a membrane bound nucleus and complex organelles. Found in Domain Eukarya – Includes Kingdoms: “Protista,” Fungi, Plantae, Animalia

“Kingdom Protista” Domain Eukarya So diverse a kingdom, that many scientists don’t consider it a true kingdom anymore Divided into two general groups: – Algae: plant-like protists. – Protozoans: animal-like protists.

Characteristics of Algae (plant-like protists) Eukaryotic (nucleus!) Can be unicellular or multicellular Mostly photosynthetic (have chloroplast) Contain cell walls (many different kinds) a.k.a. phytoplankton Our Focus now: unicellular (i.e. single cell)

DIATOMS Phylum Bascillariophyta “golden algae” – carotenoid pigments (such as xanthophyll = yellow pigment) – chlorophyll a and c Classified according to shape – Centricae: round – Pennatae: pen-shaped Buoyancy – Need to float near the surface to absorb sunlight – Adaptations to help prevent sinking by decreasing density: Radiating spines Oil droplets (lipids) Algae (plant-like protists)

DIATOMS Phylum Bascillariophyta Cell Wall – made of silica (main ingredient of glass). – Has tiny pores to allow for exchange of materials. – Also called frustule or test. Algae (plant-like protists)

Diatoms

Reproduction – Asexual: fission; two frustules separate and each half secretes a new frustule to complete the formation of the new diatom. – Sexual: diatom develops into a male or female. Male releases sperm and enter the female diatom where it unites with an egg. The fertilized egg develops into a mature diatom. DIATOMS Phylum Bascillariophyta Algae (plant-like protists)

Blooms – Occur in favorable conditions such as adequate nutrition and light – Normally spring and fall due to overturn (upwellings) – Some contain a toxin called domoic acid that can build up in plankton eating organisms Both shellfish and fish can accumulate this toxin without apparent ill effects; however, in humans the toxin crosses into the brain and interferes with nerve signal transmission. People poisoned with very high doses of the toxin can die, while lower doses can cause permanent brain damage (short term memory loss). DIATOMS Phylum Bascillariophyta Algae (plant-like protists)

Diatomaceous Earth – Dead diatom frustules fall to ocean floor – Form a thick deposit of siliceous material – Biogenous sediment: a.k.a. diatomaceous ooze – Used in many industries; good for filtering (swimming pools, drinking water, clarifying beer) and a good mild abrasive (toothpaste and polishers) DIATOMS Phylum Bascillariophyta Algae (plant-like protists)

Ecological Importance – Basis of the food chain in both marine and freshwater environments – Consumed by tiny invertebrates called copepods who are eaten by fish – Shellfish consume diatoms by filtering them out of the water DIATOMS Phylum Bascillariophyta Algae (plant-like protists)

DINOFLAGELLATES Phylum Dinophyta Unicellular Planktonic Two flagella Cell wall made of plates of cellulose Autotrophic and heterotrophic Eyespot: detect light Algae (plant-like protists)

DINOFLAGELLATES Phylum Dinophyta Flagella – Used in locomotion – One trails free – One wrapped around a groove along the middle of the cell Algae (plant-like protists)

DINOFLAGELLATES Phylum Dinophyta Reproduction and Blooms – Almost exclusively asexual (fission) – Red Tide: caused by Gymnodinium (contains a red pigment) – Gonyaulax: produces a neurotoxin that causes paralytic shellfish poisoning that can lead to illness and death in fish and humans. Algae (plant-like protists)

Red Tide (Gymnodinium)

Gymnodinium

DINOFLAGELLATES Phylum Dinophyta Some are bioluminescent :produces light (Pyrodinium) Zooxanthellae: round, golden brown dinoflagellates that live in close association with a variety of animals – Sponges – Corals – Sea anemones – Giant clams Algae (plant-like protists)

Bioluminescent Dinoflagellate

Characteristics of Protozoans (animal-like protists) Animal-like Structurally simple and very diverse Most are unicellular Heterotrophs Some are also photosynthetic Marine and freshwater as well as inside other organisms

FORMANIFERANS Phylum Granuloreticulsa Called forams Marine Have tests (shells) of calcium carbonate (CaCO 3 ) Pseudopodia: extension of cytoplasm that protrude through pores; trap food Benthic or planktonic Protozoans (animal-like protists)

Protozoans (animal-like protists)

Foraminiferan Ooze Calcareous ooze Create limestone and chalk beds Biogenous ooze Protozoans (animal-like protists)

Protozoans (animal-like protists)

RADIOLARIANS Phylum Polycystina Planktonic, marine Delicate shells of silica with radiating spines Needle-like pseudopodia that capture food Radiolarian ooze Protozoans (animal-like protists)

Protozoans (animal-like protists)

Protozoans (animal-like protists)

CILIATES Phylum Ciliophora Protozoans with cilia Cilia: hair-like and used in locomotion and feeding Planktonic or benthic Live on the gills of clams, intestines of sea urchins or on the skin of fish Paramecium: most common freshwater forms Protozoans (animal-like protists)

Protozoans (animal-like protists)