Chapter 5
Prokaryotic Metabolism
 Autotrophs
 Heterotrophs
Autotrophs
 Some bacteria and archaea make their own organic
compounds
 Primary producers
 If they do photosynthesis it takes place in on folded
membranes in the bacteria cell
 Photosynthetic bacteria account for much of the
primary production of open ocean
 Other bacterial autotrophs- chemosynthetic bacteria
Heterotrophs
 Most marine bacteria are heterotrophs
 Heterotrophs obtain energy from organic matter by
respiration
 Respiration in aerobic bacteria and archaea use oxygen
 In Anoxic sediments bacteria use anaerobic respiration
Nitrogen Fixation
 Bottom dwelling and planktonic cyanobacteria carry
out nitrogen fixation
 Nitrogen fixation N2 NH4 (covert nitrogen to
ammonium)
 Ammonium is then transferred into NO3- (nitrate)
and other N compounds
 These N sources can be used by primary producers
Unicellular Algae
 Algae – very diverse group (mostly aquatic, mostly
photosynthetic)
 Eukaryotic- cells have a nucleus, organelles
 Photosynthesis- Chloroplast
 Lack true leaves, stems, roots
 Have plant and animal characteristics- Protista
Diatoms
 Unicellular but they can be colonial or form groups or





chains
In a shell made of silica frustule (2 halves)
The perforations allow dissolved gases and nutrients
to enter and exit
Coloration- carotenoid pigments (few are colorless)
Photosynthetic factories
Some are toxic
Diatom Reproduction
 Asexual reproduction
 Auxospores- resistant stages that eventually give rise to
larger cells that display the frustule characteristic of
the species **get smaller each division**
 Favorable conditions- bloom
 Diatomaceous ooze- dead diatoms sink and form thick
deposits of siliceous material
Dinoflagellates
 Large group of planktonic unicellular organisms
 2 flagella, cell wall, plates
 Photosynthesize and ingest
 Reproduction is almost exclusively by cell division
 Bioluminescence
 Toxic
Protozoans (animal like protists)
 Eukaryotic
 Structure is simple
 Animal like
 Protozoans comprise several groups of unrelated
origins
 Heterotrophs and some photosynthesize
Foraminiferans
 Type of marine protozoan
 Have a shell (test) made of CaCO3
 Pseudopodia- extensions of the cytoplasm
 Live on the bottom either free or attached
 Shells of bottom forams are important contributors to
calcarious material
 White cliffs of Dover
Radiolarians
 Planktonic marine protozoans
 Secrete shells of glass and other materials
 Typical shells are spherical with radiating spines
 Sausage shaped colonies
 When they die and sink to the bottom they become
silicious ooze
 Resistant to dissolving under pressure
Ciliates
 Protozoans
 Lots of hair like extentions
 Locomotion and feeding
 Found all over seaweeds and in bottom sediments
 Live in gills of clams, urchin intestines,skin of fish
Fungi
 Eukaryotic and mostly multicellular
 Molds, yeasts are unicellular
 They are heterotrophs that lack chloroplasts
 500 species of marine fungi (most are microscopic)
 Decompose detritus
 Some are parasites
 Some form symbiotic relationships with algae
 lichens
Microbial world
Prokaryotes
Eukaryotes
 Bacteria
 Cyanobacteria
(stromatolites)
 Archaea
 Extremophiles
 Diatoms
 Dinoflagellates
 Protozoans (animal like)
 Foraminierans
 Radiolarians
 Fungi
Presentation
 Row 1 –Diatoms
 Row 2- Dinoflagellates
 Row 3- Foraminiferans
-Row 4 Radiolarians
 Row 5- Ciliates
 Row 6- Fungi
 Row 7: Cyanobacteria
Poster Rubric
 Image
 Definition
 At least 5 facts
 Importance to marine environment/role in marine
environment
 ** this will be a graded assignment**