METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS.pptx

Shows the different ways through which micro and macro organisms get rid of the waste products of metabolism.
There are several methods of nitrogen waste elimination, including:

1. _Exhalation_: Expelling nitrogen-rich carbon dioxide through breathing.
2. _Urination_: Eliminating nitrogen-rich urea through urine.
3. _Feces_: Excreting nitrogen-rich waste products through feces.
4. _Sweat_: Removing small amounts of nitrogen-rich compounds through sweat.

In animals:

1. _Ammonotely_: Excreting ammonia directly (e.g., fish, amphibians).
2. _Ureotelism_: Excreting urea (e.g., mammals).
3. _Uricotelism_: Excreting uric acid (e.g., birds, reptiles).

In microorganisms:

1. _Ammonification_: Converting nitrogen-rich compounds to ammonia.
2. _Denitrification_: Reducing nitrate to nitrogen gas.
3. _Nitrogen fixation_: Converting atmospheric nitrogen to usable forms.

In wastewater treatment:

1. _Nitrification_: Converting ammonia to nitrate.
2. _Denitrification_: Reducing nitrate to nitrogen gas.
3. _Nitrogen removal_: Using biological or chemical processes to remove nitrogen from wastewater.

These methods help maintain nitrogen balance in living organisms and ecosystems, and prevent excessive nitrogen buildup in the environment.
Here are the methods of nitrogen waste elimination in animals:

1. *Ammonotely*: Excreting ammonia directly, used by:
- Fish (through gills)
- Amphibians (through skin and kidneys)
- Insects (through Malpighian tubules)
2. *Ureotelism*: Excreting urea, used by:
- Mammals (through kidneys and urine)
- Some aquatic animals (like dolphins and whales)
3. *Uricotelism*: Excreting uric acid, used by:
- Birds (through kidneys and droppings)
- Reptiles (through kidneys and droppings)
- Insects (like beetles and caterpillars)
4. *Guano excretion*: Excreting nitrogen-rich guano (like seabirds and bats)
5. *Diffusion*: Some animals, like starfish and sea cucumbers, eliminate nitrogen waste through diffusion from their body surface.

These methods help animals eliminate nitrogenous waste products, which are toxic in high concentrations. The choice of method depends on factors like:

- Environment (water or land)
- Diet (high protein intake requires more efficient nitrogen elimination)
- Evolutionary adaptations

Each method has its advantages and disadvantages, and some animals use a combination of methods to eliminate nitrogen waste.
In bacteria, nitrogen waste elimination occurs through various mechanisms:

1. _Ammonification_: Bacteria like Escherichia coli (E. coli) convert nitrogen-rich compounds into ammonia (NH3), which is then released.
2. _Denitrification_: Bacteria like Pseudomonas and Bacillus reduce nitrate (NO3-) to nitrogen gas (N2), releasing it into the environment.
3. _Nitrogen fixation_: Certain bacteria, like Rhizobia and Frankia, convert atmospheric nitrogen (N2) into a usable form, such as ammonia or nitrate.
4. _Urease activity_: Some bacteria, like Proteus and Klebsiella, break down

1. METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS Ammonotelism This is the process by which nitrogenous waste is eliminated from the body in form of ammonia solution. Ammonia is formed from oxidation of amino groups eliminated from proteins during deamination. It is highly soluble in water and causes alkaline caustic action in high concentrations. Ammonotelic organisms include bony fish, flat worms protozoans and most of the aquatic animals.

2. METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS Ureotelism In some mammals and amphibians which live in terrestrial environment, the ammonia from deamination is converted into urea through the ornithine cycle in an attempt to conserve water since urea requires little water for excretion.

3. METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS Uricotelism Uricotelic organisms such as birds, insects and reptiles convert the ammonia from purine breakdown into uric acid using the complex inosinic pathway . The process is more energy demanding than in ureotelism but requires almost no water is required for excretion. Human beings also secrete uric acid from breakdown of body purines as well as from dietary foods like liver and peas. Uric acid is vital to the body as an anti oxidant in regulated amounts while high concentrations lead to its precipitation in the kidneys causing kidney stones and GOUT in joints.

4. METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS Amminotelism Certain molluscs such as the octopus and echinoderms like starfish can directly excrete the nitrogen in form of amino acids directly out of their bodies in case of excess. Guanotelism Arachinids like spiders and scorpions convert the ammonia into guanine(purine) before excretion. It’s insolubility indicates that no water is required for its excretion. Guanine is directly excreted out of their bodies without joining the Inosinic pathway.

5. METHODS OF NITROGEN EXCRETION IN DIFFERENT ORGANISMS OTHER EXCRETIONS(Micro organisms) 1.Denitrifying bacteria such as pseudomonas and achromobacter release nitrogen in gaseous form into the atmosphere in the nitrogen cycle. 2.Putrefying bacteria like Eschericia and enterobacter convert the decomposing matter into solid ammonium compounds released into the soil. 3.Nitrogen is also released as nitrates and nitrites into the soil by bacteria species Nitrobacter and Nitrosomonas respectively .

6. THE UREA CYCLE

7. THE UREA CYCLE Urea cycle is a series of enzyme catalysed reactions that involve production of urea from ammonia following the deamination of ammino acids in the liver. The cycle comprises two phases that is mitochondrial and cystolic phase. In the mitochondria, the processes are initiated by the synthesis of carbamoyl phosphate a reaction catalysed by Carbamoyl phosphate synthetase 1 .In this reaction Ammonium ions from deamination react with bicarbonate ions leading to formation of carbamoyl phosphate intermediate. 2ATP molecules are utilized forming 2ADP molecules and 2Pi The enzyme Carbamoyl phosphate synthetase is allosterically activated by N-acetyl glutamate which is synthesized by N-acetyl glutamate synthase when acetyl coA reacts with glutamate.

8. THE UREA CYCLE The Carbamoyl phosphate undergoes a condensation reaction with L-ornithine in the mitochondria catalysed by Ornithine transcarbamylase hence forming L-citrulline and this marks the end of the mitochondrial phase of the cycle. The L-citrulline formed diffuses out of the mitochondria into the cytoplasm to initiate the reactions of the cystolic phase. In the cytoplasm, L-citrulline undergoes a condensation reaction with L-Aspartate catalysed by Arginosuccinate synthetase leading to formation of Arginosuccinate(first intermediate in cystol).One molecule of ATP is used to form AMP and an inorganic pyrophosphate. Arginosuccinate undergoes cleavage to L-arginine by enzyme Arginosuccinate lyase with the release of L-fumarate (TCA).

9. THE UREA CYCLE L-arginine is then broken down by Arginase 1 enzyme in presence of water to form L-ornithine which migrates into the mitochondria to act as a substrate in the second mitochondrial phase reaction which involves synthesis of L-citrulline. Urea is produced at this stage in the liver from where it migrates to the kidneys for its excretion in form of urine. NB : The urea cycle is the only source of endogenous Citrulline, arginine and ornithine.

10. TRI-METHYL AMINE OXIDE Tri-methyl amine oxide is produced as tri methyl amine from dietary phosphatidyl choline and carnitine by the intestinal bacteria from where it moves to the liver where it is oxidized to TMAO by the Flavin Monooxygenases . It is utilized as a protein stabilizer for the urea cycle enzymes while the marine bony fishes can also utilize it as an osmolyte. High quantities of the compound in the body can lead to atherosclerosis by denying cholesterol accessibility to its transport receptors in and out of the enterocytes.