6.10 Cyanobacteria
Why cyanobacteria are considered as the most prominent of the photosynthetic bacteria?
Cyanobacteria played a major role in the evolution of life. They were the first oxygen-producing organisms. Their photosynthetic activity gradually oxygenated the
land about two billion years ago. The level of oxygen increased by beet 21%. The amount of cases also increased in the upper by cyanobacteria. The oven acted as a screen to protect the macrocarbon destruction by violet radiation from the
other autotrophs to appear and survive on Earth. Many of our one thing) are involved in the fixation of atmospheric nitrogen Arahane and Nostoc are purposely cultivated to increase the s ty, because of the nitrogen fixation ability of these organisms.
Characteristics of Cyanobacteria
Habitat:
These are found in damp places, salt water, fresh water, moist soil, hot qings (with temperature
Mode of life: Maybe epiphytic and symbiotic For of life: May be unicellular and solitary, exist as omics of any shapes, or form filaments consisting of diseases) surrounded by mucilaginous
Call wall is Gram-negative type (contains lipopolysaccharides, lipoprotein peptidoglycan
Synthetic System closely resembles eukaryotes cyanobacteria chlorophyll and photosystem II, which use water as an electron donor and get y during photosynthesis. They have phycobilins as accessory pigments Phy is their predominant pigment. Photosynthesis takes place in the stresses of the beast, which is placed in the periphery of the cytoplasms.
6.10.1 Pigment Composition in Cyanobacteria
Cyanobacteria possess two accessory pigments, ie, phycocyanin (blue pigment) and phycoerythrin (red pigment). In some species, the mixture of chlorophyll and blue pigment produces the blue-green color, thus sometimes known as blue-green algae. But the other species contain red pigments and appear red, purple-brown, or even black. 6.10.2 Difference between the photosynthetic mechanisms in cyanobacteria and photosynthetic bacteria.
The photosynthetic bacteria release sulfur whereas cyanobacteria release oxygen during photosynthesis. The source of hydrogen in bacteria is hydrogen sulfide whereas cyanobacteria like plants obtain hydrogen from water.
The photosynthetic bacteria have photosystem I but lack photosystem II, thus only cyclic electron flow is the sole means of generating ATP while cyanobacteria have chlorophyll and photosystem II.
In cyanobacteria, the photosynthetic pigment and electron transport chain components are placed in the thylakoid membrane linked with particles called phycobilisomes. Phycocyanin is their predominant phycobilin (Pigments) and CO, in them is assimilated through the Calvin cycle.
Make a Mat of characteristics of Cyanobacteria and write some advantages of Cyanobacteria concerning soil fertility Critical Thinking.
1. Life is not possible without bacteria Why?
Give ornaments to apport this statement 2. Why bacteria are widely used in biotechnological processes?
SUMMARY
• Bacteria are the oldest and simplest organisms, but they are metabolically much more diverse than all other life forms combined.
Bacteria differ from eukaryotes in many ways, the most important of which is the degree of internal organization within the cell.
⚫ Most bacteria have cell walls that consist of a network of polysaccharide molecules connected by polypeptide cross-links.
• A bacterial cell does not possess specialized compartments or a membrane-bounded nucleus, but it may exhibit a nucleoid region where the bacterial DNA is located. • The two bacterial kingdoms, Archaebacteria and Eubacteria, are made up of prokaryotes, with about 30,000 species formally being named so far.
The Archaebacteria differ markedly from Exbacteria and from eukaryotes in their ribosomal sequences and in other respects
• Mutation and genetic recombination are important sources of variability in bacteria. Many bacteria are autotrophic and make major contributions to the world in maintaining carbon balance. Others are heterotrophic and play a key role in the ecosystem by breaking down organic compounds
• Some heterotrophic bacteria cause major diseases in plants and animals.
⚫ Human diseases caused by pathogenic bacteria include many fatal diseases that have had major impacts on human history, including tuberculosis, cholera, plague, and typhus.
0 Comments