Transcript sprulina - Ethio Celebrities

What are PROKARYOTES?
They are ancient life forms
known as bacteria
• No true nucleus
• No chloroplasts
• No mitochondria
other organelles
Two major classes of bacteria
Archaebacteria
Methanogens
Extreme
Thermophiles
Extreme Halophiles
TEM of dividing cell
& Eubacteria
Cyanobacteria (Blue-green algae)
Gram negative bacteria
Gram positive bacteria
& other
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THE FOLLOWING ARE
DIVISION
◦ CYANOPHYTA-Blue green algae
Some Characteristics of the
Cyanobacteria
* Contain Chlorophyll a and carotenoids,
plus the phycobilins (proteinaceous
photosynthetic pigments) phycocyanin and
phycoerythrin (c f. Rhodophyta), found in
thylakoids
* Have cell walls of peptidoglycan, often
with a mucilaginous sheath
* The carbohydrate stored is glycogen
* No flagella, but some exhibit gliding
movements
* Some fix nitrogen in specialized cells
In some genera the mucilaginous
sheath forms a gelatinous matrix
Gelatino
us
matrix
Individua
l cells
Gloeocapsa
Filaments of Nostoc
commune forming a
gelatinous ball
Division Cyanophyta
Bacteria
that are:
• Photosynthetic (convert
light energy to food)
• Produce O2 as a byproduct of
photosynthesis
• Some produce toxins
• Some have capacity to fix N2 into NH4
TEM of dividing cell
• Some have formed millions of years old
stromatolites as living structures
Cyanophytes have changed the path of evolution on
Ancient organisms but
well suited to earth’s
habitats
2000 species,
150 genera
Habitats:
virtually everywhere
Oceans
Freshwater
Soil
Hotsprings
Epiphytes
Endophytes
Morphological
Range:
Unicells
to complex
multicell organisms
Cell Walls:
Gram negative bacteria
Trichodesmium blooms can cover
2x106 km2 and be seen via satellites
NASA
Diversity
CLASS-CYANOPHYCEAE
ORDER-CHROOCOCCALES
Gloeocapsa
Merismopedia
microcystis
ORDER-OSCILATORIALES
Oscilatoria
Lyngbya
Nostoc
Anabaena
Diversity
Order Chroococcales
Microcystis
Merismopedia
Diversity
Order Nostocales
Growth &
morphology
:
False branching
1. Rupture of sheath and cells
2. Remaining cells at both ends
continue to grow
3. Both trichomes push
through weakened sheath
What to look for?
Is there a change in the plane
of cell division?
Order Nostocales
New Cell Types
Order Nostocales
Nitrogen fixation
supports protein
synthesis
1. Low N in environment
2. Cell differentiates as a specialized
cell, the heterocyst
3. Creates setting for Nitrogenase
enzyme
4. Enzyme converts N2  NH4+
polar heterocysts
Growth &
morphology
Order Nostocales
Nitrogen fixation & Azolla
in rice fields replace
fertilizers
1. Low N in environment
2. Heterocysts differentiate
3. Enzyme converts N2  NH4+
4. Water fern benefits from fertilizer
5. Rice fields are more productive
intercalary heterocysts
Akinete
Anabaena
Order Nostocales
Cool stuff
Order Nostocales