Introduction Marine Synthesis - part 1 - Gidon Flashcards
(Some of) the main players in Marine photosynthesisers
- Cyanobacteria
- Phyto / zooplankton – how do we study plankton in the sea ?
- Algal (Algae)
- Seagrasses
- Corals (photoinhibtion)
How many percent Earth’s surface cover by OCEAN?
Approximately 71%
How many percent Earth’s surface cover by WATER?
Approximately 72%
What is Primary productivity?
The net amount of CO2 taken up over time
How many percent of global PRIMARY PRODUCTION do by AQUATIC PLANTS?
> = 50% (photosynthesis) of Global
How many Global primary production do by TERRESTRIAL?
Estimated at 60 Gt carbon/year
How many Global primary production do by MARINE?
Estimated at 65 Gt carbon/year
>5 Gt compared w terrestrial
What are these advantage of OCEAN compare w LAND?
- AREA
- VOLUME
The elevation of the land surface of the Earth?
- 418 m (Dead Sea) to 8,848 m (Everest)
AVERAGE height of land above sea level is?
840 m
The deepest of the oceans??
-10,994 m (Mariana Trench)
How many times An Ocean’s average depth bigger than AVERAGE height of land above sea level ?
4.5 times
What is the process of PS?
CO2 + H2O C6H12O6 + O2
What is the process of Chemosynthesis?
CO2 + H2O + H2S + O2 C6H12O6 + H2SO4
What is The “primary producers” of Chemosynthesis process?
Chemosynthetic bacteria (use H2S)
What is the photic zone?
Enough light for net photosynthesis (average 100 m depth)
What are these PS producer in Photic zone?
- Cyanobacteria
- Macro algae
- Phytoplankton
- Coral reef
- Seagrass meadows
What is Cyanobacteria?
Prokaryotic unicellular
or filamentous phytoplankton
What is the Habitat of Cyanobacteria?
Everywhere (terrestrial and aquatic habitat),
( the most successful group of microorganisms on earth.)
Can be found in the most extreme niches: hot springs, salt works, and hypersaline bays.
How many Cyanobacteria species?
1500 species (10% marine)
Two main species?
Unicellular and colonial species
What kind of form of Colonies (colonial species) ?
- Filaments (can be attached to sediment,
seagrasses / macro algae (biofilms) - Sheets
- Hollow balls
What is the name of Unicellular cyanobacteria discovered in 1986?
- Prochlorococcus (1986)
Name of 2 photosynthetic cyanobacteria - primary
producers in the ocean, responsible for at least 50% of atmospheric oxygen?
Prochlorococcus
and Synechococcus
What is the habitat of filamentous cyanobacteria?
Found in nutrient poor tropical and subtropical ocean waters.
(can live in solitude or in colonies (form of colonies: blooms or can be extensive on surface waters ).
More information about cyanobacteria (Trichodesmium)?
Cyanobacteria are Diazotrophes
(dia = two, azo = nitrogen, only prokaryots)
- Fixes atmospheric nitrogen into ammonia
- Biological nitrogen fixation: N2 + 8 H+ + 8 e− → 2 NH3 + H2
- This process requires a substantial amount of energy (in the form of ATP) in order to
break the triple bond between the nitrogen atoms
Why do we call Marine diazotrophs are Global biochemical cycle of N?
Because Marine diazotrophs fix 150,000,000-200,000,000 tons (0.15-0.20 Gt) atmospheric N2 yr-1
Not all Cyanobacteria are unicellular but have filamentous cyanobacteria.
What is the name of one of them ?
Trichodesmium
The Dilemma with cyanobacteria
The enzyme nitrogenase (enzyme fix N2) is extremely sensitive to oxygen - inactivated by oxygen - (thus requires a near‐to‐anoxic environment)
and Oxygen production during photosynthesis.
Solution of The Dilemma with cyanobacteria
- Heterocysts (meaning: no photosynthesis), create a micro-anaerobic environment,
- Nitrogen fixation during the night
- Nitrogen fixation within dense flakes of filamentous cyanobacteria , the centre being oxygen depleted (no Oxi)
What is the special of filamentous cyanobacteria (diazotrophes) - Trichodesmium
Iin tropical seas, responsible for fixing one quarter of the nitrogen in the world’s ocean.
Fixing nitrogen – summary:
The enzyme complex responsible for the fixation of N2.
Is sensitive to oxygen and requires a near‐to‐anoxic environment.
Cyanobacteria are phototrophic organisms evolving oxygen and they
developed various strategies to combine this with N2 fixation.
In order to fix N2, cyanobacteria separate the incompatible processes of oxygenic photosynthesis and N2 fixation spatially (in different cells) or temporally (during the night), or a combination of both.
Another function of Cyanobacteria: “Earth food”.
What is the name one of them?
Spirulina sp.
(Rich in protein, vitamins, minerals, and carotenoids,
Especially, antioxidants that can help protect cells from damage)
The theory from Prokaryotes (cyanobacteria) to eukaryotes (microalgae)
Endosymbiotic theory:
evolutionary theory that explains the origin of eukaryotic cells from prokaryotes .
The proof of The theory from Prokaryotes (cyanobacteria) to eukaryotes (microalgae) -
(Endosymbiotic theory)
The Mitochondrion (found in most eukaryotic cells) and the chloroplasts (found in all eukaryotic algae) evolved from cyanobacterial ancestors via endosymbiosis
2 types of Endosymbiotic theory:
- Primary endosymbiosis: Prkaryote + Eukaryote = Eukaryote
- Secondary endosymbiosis: eukaryote cell engulfs another eukaryote cell that has undergone primary endosymbiosis
(Eukaryote + Eukaryote = Eukaryote)
