Why are hetercysts in cyanobactiria critical components of the nitrogen cycle?
Since this is not my area of expertise, I searched Google under the key words "heterocysts cyanobacteria nitrogen" to get these possible sources: (It helps more if you spell the key words correctly.)
http://209.85.173.104/search?q=cache:5Ees-C7FBmQJ:www.esf.org/index.php%3FeID%3Dtx_ccdamdl_file%26p%255Bfile%255D%3D4366%26p%255Bdl%255D%3D1%26p%255Bpid%255D%3D3831%26p%255Bsite%255D%3DEuropean%2520Science%2520Foundation%26p%255Bt%255D%3D1205614447%26hash%3Dd669d5d702b43e0daf21597eff261f8b%26l%3Den+heterocysts+cyanobacteria+nitrogen&hl=en&ct=clnk&cd=1&gl=us&client=safari
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TD1-3TVX7D7-9&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d036dc71d03b29149d0534970593b189
(Broken Link Removed)
http://www.earthlife.net/prokaryotes/cyano.html
http://www.plantphysiol.org/cgi/reprint/100/1/157.pdf
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.
Heterocysts are critical components of the nitrogen cycle in cyanobacteria because they play a key role in the fixation of atmospheric nitrogen into a form that can be used by other organisms. Nitrogen is an essential nutrient for all living organisms, but it exists primarily in an inert form as atmospheric nitrogen (N2), which cannot be directly utilized by most organisms.
To understand why heterocysts are critical, let's break down the nitrogen cycle and their role in it:
1. Nitrogen fixation: Heterocysts are specialized cells found in some filamentous cyanobacteria. These cells are capable of fixing atmospheric nitrogen by converting it into ammonia (NH3) or ammonium ions (NH4+), which are forms of nitrogen that other organisms can use. This process is carried out by an enzyme called nitrogenase, which is exclusive to heterocysts. The presence of heterocysts allows cyanobacteria to convert atmospheric nitrogen into a usable form.
2. Nitrogen assimilation: After the heterocysts fix atmospheric nitrogen, the ammonia produced is transferred to adjacent cells in the cyanobacterial filament. These neighboring cells, called vegetative cells, lack nitrogenase, but they have the necessary enzymes to assimilate the ammonia into organic compounds, such as amino acids and proteins. This enables the cyanobacteria to utilize the fixed nitrogen for their own growth and metabolism.
3. Nitrogen recycling: Once the cyanobacteria have assimilated the fixed nitrogen, it can be incorporated into various organic molecules and passed up the food chain as organisms feed on the cyanobacteria. Eventually, these nitrogen-containing compounds are decomposed by other organisms, releasing ammonia back into the environment. This ammonia can then be taken up by other organisms or undergo further transformations in the nitrogen cycle.
So, to summarize, heterocysts are critical components of the nitrogen cycle because they allow cyanobacteria to convert atmospheric nitrogen into a usable form (nitrogen fixation). This fixed nitrogen is then assimilated into organic compounds, utilized by cyanobacteria, and recycled back into the environment for other organisms to utilize.