Please help answer the questions below, thanks . How does nitrogen fixation occu
ID: 212438 • Letter: P
Question
Please help answer the questions below, thanks
. How does nitrogen fixation occur? Is this a universal process that occurs in most organisms? What components are necessary for nitrogen fixation? How is nitrogen fixation regulated? . How does fixed nitrogen get transferred to the various amino acids and nucleotides? . What are the sources for the Carbon skeletons of the amino acids and nucleotides? How is nitrogen removed from amino acids and nucleotides? » What is the fate of the removed nitrogen? C)Explanation / Answer
1) Nitrogen fixation is the first step of nitrogen cycle. Nitrogen is most imp. chemical which could be found in every essential biomolecule is our body from DNA RNA to proteins etc. But, nitrogen is present in the air. So we need to incorporate nitrogen in our body. Here comes the need of nitrogen fixation. But every organism is not able to fix nitrogen in its body for eg, human cannot fix nitrogen from atmosphere. There are some specific microbes in ecosystem only they can fix it. In simple words, Nitrogen exists in atmosphere as N2. Some microbes break the bond between two molecule of nitrogen and join it with oxygen or hydrogen to form ammonia or nitrates. Formation of ammonia or nitrate means than nitrogen is fixed and canbe utilized.
Not all organism can fix this. Those who have nitrogenase enzyme can only convert the atmospheric nitrogen. Only some specialised microbes such as clostridium, azotobactor , rhizobium etc. can fix nitrogen.
2) nitrogenase production is necessary for nitrogen fixation as it converts the atmospheric nitrogen into ammonia or nitrate.
3) nitrogen fixation is regulated at gene level. nif gene is responsible for production of nitrogenase enzyme. And it also produces regulatory proteins for fixing pathways. When there is low amount of fixed nitrogen, nif gene is triggered to produce more nitrogenase which inturn increases nitrogen fixation. And when there is more concentration of ammonia in surroundings, nif gene is expressed less.
4) After ammonia is produced, it goes directly into downstream processes. Where it acts with glutamate and sends the amino group to form glutamine, amino acid. This glutamine again transfer amino group to aspertate to convert it into asparagine. Like wise, chain reaction helps to transfer the amino group which is formed from fixed amino acid and incorporation happens.
5) the source of carbon of living being is glucose. One molecule of glucose has 6 carbon atom. After breaking down of glucose molecule, carbons are transferred to different biomolecules like nucleotide, amino acids by different biochemical pathways.
6) it is removed by a process called deamination. It occurs via two method. Oxidative and non oxidative. Here the amine group which includes the nitrogen atom, is removed from the amino acid.
7) it is released from body as a waste material or excretory product. Different animal produces different nitrogenous excretion like ammonia, urea, uric acid. These compounds have removed nitrogen in it. And nitrogen goes back to the environment.