Post on 26-Dec-2015
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Kingdom Monera
What are PROKARYOTES?
TEM of dividing cell
• No true nucleus• No chloroplasts
• No mitochondria other organelles
They are ancient life forms
known as bacteria
Two major classes of bacteria
Archaebacteria & Eubacteria
Methanogens Extreme Thermophiles Extreme Halophiles
Cyanobacteria (Blue-green algae) & other
Gram negative bacteriaGram positive bacteria
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 called heterocysts
In some genera the mucilaginous sheath forms a gelatinous matrix
Gelatinous matrixIndividual cells
Gloeocapsa
Filaments of Nostoc commune forming a
gelatinous ball
Bacteria that are:
• Photosynthetic (convert light energy to food)
• Produce O2 as a byproduct of photosynthesis
• Some have capacity to fix N2 into NH4
• Some produce toxins
• Some have formed millions of years old stromatolites as living structures
Division Cyanophyta
TEM of dividing cell
Cyanophytes have changed the path of evolution on earth
General features
150 genera2000 species,
Habitats:virtually everywhere
Oceans Freshwater
Soil Hotsprings
Epiphytes
Gram negative bacteria
Morphological Range:
Endophytes
Cell Walls:
Ancient organisms but well suited to earth’s habitats
Unicells to complex multicell organisms
Trichodesmium blooms can cover 2x106 km2 and be seen via satellites NASA
DIVISION CYANOPHYTA
CLASS-CYANOPHYCEAEORDER-CHROOCOCCALES
GloeocapsaMerismopediamicrocystis
ORDER-OSCILATORIALESOscilatoriaLyngbyaNostocAnabaena
Growth &morphology Order Nostocales
False branching1. 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?
New Cell Types
Nitrogen fixation supports protein synthesis1. 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
Order Nostocales
Growth &morphology Order Nostocales
Nitrogen fixation & Azolla in rice fields replace fertilizers1. Low N in environment
2. Heterocysts differentiate
3. Enzyme converts N2 NH4+
4. Water fern benefits from fertilizer
intercalary heterocysts
5. Rice fields are more productive