1. Objectives: S.W.B.A.T Describe the Nitrogen Cycle. Discuss how communities in an ecosystem are involved in the Nitrogen Cycle. Explain the importance of the Nitrogen Cycle in the environment.

2. DO NOW: Think about the following questions: 1)W hich macromolecule contains Nitrogen as one of its elements? 2)W hat is the basic unit of proteins? 3)H ow does the body get-rid off the excess nitrogenous wastes? These questions look very difficult and complicated. Lets start at the beginning.

3. Nitrogen gas (N 2 ) makes up 79% of our atmosphere Nitrogen is needed by plants and animals to make proteins and DNA It ranks fourth behind oxygen, carbon, and hydrogen as the most common chemical element in living tissues. Most organisms CAN NOT obtain nitrogen through the atmosphere! If nitrogen is so important, then how do we get it? The Nitrogen Cycle

5. Most organisms can only use nitrogen in the form of nitrate (NO 3 - ). Most of the conversion of N 2 to these compounds takes place under ground through bacteria. This is called: Nitrogen Fixation.

6. Nitrogen Fixation: Bacteria convert gaseous nitrogen to ammonia: (N 2 ) (NH 3 ) Some ammonia enters the ground normally through waste and decay as well (pee, poop and dead things). Different bacteria convert ammonia to nitrite: (NH 3 ) (NO 2 - ) Bacteria use nitrite as an energy source, and give off nitrate (NO 3 - ) as waste: Nitrate is then taken up by plants or released into the atmosphere, where it becomes gaseous N 2 again. (NO 3 - ) (N 2 )

8. Some plants (legumes) have nodules on their roots where nitrogen-fixing bacteria live.

9. Credits: Images:  http://earth.rice.edu/MTPE/bio/biosphere/topics/energy/nitrogen_cycle.gifhttp://earth.rice.edu/MTPE/bio/biosphere/topics/energy/nitrogen_cycle.gif  http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/nitrogen_ cycle_EPA.jpg http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/nitrogen_ cycle_EPA.jpg  http://www.paintthelight.net/BotanyProject/Activities/uses_plants.htmhttp://www.paintthelight.net/BotanyProject/Activities/uses_plants.htm  http://runforlife3.wordpress.com/2009/04/15/peanut-peanut-butter-and-jelly/http://runforlife3.wordpress.com/2009/04/15/peanut-peanut-butter-and-jelly/ Links:  http://www.youtube.com/watch#!v=R8-E6cDCr5Uhttp://www.youtube.com/watch#!v=R8-E6cDCr5U 