Prokaryotes and “Kingdom Protista”

Domain Eubacteria Domain Archae

The Prokaryotes

Cell type: Prokaryotes

• Found in:

– Domain Bacteria

– Domain Archae

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 SO4-2 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 Phylum Bascillariophyta

• 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.

Algae

(plant-like protists)

DIATOMS Phylum Bascillariophyta

• 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).

• 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

• 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

Diatoms

DINOFLAGELLATES Phylum Dinophyta

• Unicellular

• Planktonic

• Two flagella

• Cell wall made of plates of cellulose

• Autotrophic and heterotrophic

• Eyespot: detect light

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)

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)

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

FORMANIFERANSPhylum Granuloreticulosa

• Called forams

• Marine

• Have tests (shells) of calcium carbonate (CaCO3)

• Pseudopodia: extension of cytoplasm that protrude through pores; trap food

• Benthic or planktonic

Protozoans

(animal-like protists)

Foraminiferan Ooze

• Calcareous ooze

• Create limestone and chalk beds

• Biogenous ooze

Protozoans

(animal-like protists)

RADIOLARIANSPhylum 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)

CILIATESPhylum 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)