banner



Home  ›  Give Examples Of Animals That Excrete Ammonia As Such,, Or As Urea Or Uric Acid?

Give Examples Of Animals That Excrete Ammonia As Such,, Or As Urea Or Uric Acid?

Written By Saturday, May 28, 2022 Add Comment Edit

Osmotic Regulation and Excretion

218 Nitrogenous Wastes

Learning Objectives

Past the end of this section, yous volition be able to exercise the following:

  • Compare and dissimilarity the way in which aquatic animals and terrestrial animals can eliminate toxic ammonia from their systems
  • Compare the major byproduct of ammonia metabolism in vertebrate animals to that of birds, insects, and reptiles

Of the 4 major macromolecules in biological systems, both proteins and nucleic acids contain nitrogen. During the catabolism, or breakdown, of nitrogen-containing macromolecules, carbon, hydrogen, and oxygen are extracted and stored in the class of carbohydrates and fats. Excess nitrogen is excreted from the body. Nitrogenous wastes tend to course toxic ammonia, which raises the pH of trunk fluids. The formation of ammonia itself requires free energy in the form of ATP and large quantities of water to dilute it out of a biological arrangement. Animals that live in aquatic environments tend to release ammonia into the water. Animals that excrete ammonia are said to be ammonotelic. Terrestrial organisms have evolved other mechanisms to excrete nitrogenous wastes. The animals must detoxify ammonia by converting it into a relatively nontoxic form such every bit urea or uric acrid. Mammals, including humans, produce urea, whereas reptiles and many terrestrial invertebrates produce uric acid. Animals that secrete urea as the main nitrogenous waste textile are called ureotelic animals.

Nitrogenous Waste matter in Terrestrial Animals: The Urea Cycle

The urea bicycle is the chief mechanism by which mammals convert ammonia to urea. Urea is made in the liver and excreted in urine. The overall chemical reaction by which ammonia is converted to urea is ii NHthree (ammonia) + COii + 3 ATP + H2O → H2Northward-CO-NHii (urea) + 2 ADP + 4 Pi + AMP.

The urea cycle utilizes v intermediate steps, catalyzed past five different enzymes, to convert ammonia to urea, as shown in (Effigy). The amino acid 50-ornithine gets converted into different intermediates earlier being regenerated at the end of the urea cycle. Hence, the urea cycle is also referred to as the ornithine bike. The enzyme ornithine transcarbamylase catalyzes a key pace in the urea wheel and its deficiency tin can lead to accumulation of toxic levels of ammonia in the trunk. The first two reactions occur in the mitochondria and the last iii reactions occur in the cytosol. Urea concentration in the blood, called claret urea nitrogen or BUN, is used as an indicator of kidney function.

The urea cycle converts ammonia to urea.


The urea cycle begins in the mitochondrion, where bicarbonate, shown as upper case H upper case C upper case O subscript 3 baseline is combined with ammonia, shown as upper case N upper case H subscript 3 baseline to make carbamoyl phosphate. Two A T P are used in the process. Ornithine transcarbamylase adds the carbamoyl phosphate to a five-carbon amino acid called ornithine to make L citrulline. L citrulline leaves the mitochondrion, and an enzyme called arginosuccinate synthetase adds a four carbon amino acid called L aspartate to it to make arginosuccinate. In the process, one A T P is converted to A M P and upper case P upper case P lower case i. Arginosuccinate lyase removes a four carbon fumarate molecule from the arginosuccinate, forming the six carbon amino acid L arginine. Arginase 1 removes a urea molecule from the L arginine, forming ornithine in the process. Urea has a single carbon double bonded to an oxygen and single bonded to two ammonia groups. Ornithine enters the mitochondrion, completing the cycle.

Evolution Connection

Excretion of Nitrogenous WasteThe theory of evolution proposes that life started in an aquatic environment. It is not surprising to run across that biochemical pathways like the urea cycle evolved to suit to a changing environment when terrestrial life forms evolved. Arid conditions probably led to the development of the uric acrid pathway as a means of conserving water.

Nitrogenous Waste material in Birds and Reptiles: Uric Acid

Birds, reptiles, and most terrestrial arthropods catechumen toxic ammonia to uric acid or the closely related chemical compound guanine (guano) instead of urea. Mammals also form some uric acid during breakdown of nucleic acids. Uric acid is a compound like to purines found in nucleic acids. It is h2o insoluble and tends to grade a white paste or powder; it is excreted by birds, insects, and reptiles. Conversion of ammonia to uric acrid requires more free energy and is much more than complex than conversion of ammonia to urea (Figure).

Nitrogenous waste matter is excreted in different forms by dissimilar species. These include (a) ammonia, (b) urea, and (c) uric acid. (credit a: modification of piece of work by Eric Engbretson, USFWS; credit b: modification of piece of work by B. "Moose" Peterson, USFWS; credit c: modification of work past Dave Menke, USFWS)


Part A shows a photo of a freshwater fish and states that many invertebrates and aquatic species excrete ammonia. The chemical structure of ammonia is upper case N upper case H subscript 3 baseline. Part B shows a photo of a wood rat and states that mammals, many adult amphibians, and some marine species excrete urea. The chemical structure of urea is shown. Urea has one upper N upper H subscript 2 baseline group, and one upper N upper H subscript 2 baseline group attached to a central carbon. An oxygen is also double-bonded to this central carbon. Part C shows a photo of a pigeon and states that insects, land snails, birds, and many reptiles excrete uric acid. The chemical structure of uric acid is shown. Uric acid has a six-membered carbon ring attached to a five-membered ring. Each ring has two upper N upper H groups embedded in it. An oxygen is double-bonded to each ring.

Everyday Connection

GoutMammals use uric acrid crystals as an antioxidant in their cells. Nonetheless, too much uric acid tends to form kidney stones and may also cause a painful condition called gout, where uric acid crystals accumulate in the joints, as illustrated in (Figure). Food choices that reduce the amount of nitrogenous bases in the nutrition assist reduce the take a chance of gout. For example, tea, coffee, and chocolate have purine-similar compounds, called xanthines, and should be avoided by people with gout and kidney stones.

Gout causes the inflammation visible in this person'southward left big toe articulation. (credit: "Gonzosft"/Wikimedia Commons)


Photo shows a person's feet. One foot is swollen and red, while the other appears normal.

Section Summary

Ammonia is the waste material produced by metabolism of nitrogen-containing compounds like proteins and nucleic acids. While aquatic animals tin can easily excrete ammonia into their watery surroundings, terrestrial animals have evolved special mechanisms to eliminate the toxic ammonia from their systems. Urea is the major byproduct of ammonia metabolism in vertebrate animals. Uric acrid is the major byproduct of ammonia metabolism in birds, terrestrial arthropods, and reptiles.

Review Questions

BUN is ________.

  1. blood urea nitrogen
  2. blood uric acid nitrogen
  3. an indicator of blood volume
  4. an indicator of blood pressure

A

Human being beings accumulate ________ before excreting nitrogenous waste matter.

  1. nitrogen
  2. ammonia
  3. urea
  4. uric acid

C

Disquisitional Thinking Questions

In terms of evolution, why might the urea wheel have evolved in organisms?

It is believed that the urea cycle evolved to conform to a changing surround when terrestrial life forms evolved. Arid conditions probably led to the development of the uric acid pathway as a means of conserving water.

Compare and contrast the germination of urea and uric acid.

The urea wheel is the primary machinery by which mammals convert ammonia to urea. Urea is made in the liver and excreted in urine. The urea bicycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea. Birds, reptiles, and insects, on the other manus, catechumen toxic ammonia to uric acrid instead of urea. Conversion of ammonia to uric acrid requires more energy and is much more circuitous than conversion of ammonia to urea.

Glossary

ammonia
compound made of i nitrogen atom and three hydrogen atoms
ammonotelic
describes an animal that excretes ammonia as the primary waste matter material
antioxidant
agent that prevents cell destruction past reactive oxygen species
blood urea nitrogen (BUN)
estimate of urea in the blood and an indicator of kidney function
urea cycle
pathway by which ammonia is converted to urea
ureotelic
describes animals that secrete urea every bit the principal nitrogenous waste material fabric
uric acid
byproduct of ammonia metabolism in birds, insects, and reptiles

Source: https://opentextbc.ca/biology2eopenstax/chapter/nitrogenous-wastes/

Posted by: montanoyousticheare.blogspot.com

0 Response to "Give Examples Of Animals That Excrete Ammonia As Such,, Or As Urea Or Uric Acid?"

Post a Comment

Subscribe to: Post Comments (Atom)

Iklan Atas Artikel

Iklan Tengah Artikel 1

Iklan Tengah Artikel 2

Iklan Bawah Artikel