Nitrogenous waste Watch

This discussion is closed.
Fluent in Lies
Badges: 0
Rep:
?
#1
Report Thread starter 13 years ago
#1
Out of interest. Why doesn't all life excrete Uric Acid if it is less toxic and you dont need to lose water in getting rid of it. Is the process of its production more complex?

Surely urea is inefficient if water is lost in its excretion. Allright with fish, there is water avaiblable anyway, so thats not a problem.
0
Golden Maverick
Badges: 2
Rep:
?
#2
Report 13 years ago
#2
(Original post by Fluent in Lies)
Out of interest. Why doesn't all life excrete Uric Acid if it is less toxic and you dont need to lose water in getting rid of it. Is the process of its production more complex?

Surely urea is inefficient if water is lost in its excretion. Allright with fish, there is water avaiblable anyway, so thats not a problem.
Urea is a result of protein metabolism, and uric acid of nucleic acid metabolism.

If the concentration of uric acid gets too high in our blood, you get gout, where the acid crystallises in your joints. Also they help give you kidney stones.

I think animals that do excrete uric acid have an enzyme to stop this from happening, by making it soluble but I think this has been switched off in humans. Why, I don't know.
0
Seth
Badges: 8
Rep:
?
#3
Report 13 years ago
#3
(Original post by Fluent in Lies)
Surely urea is inefficient if water is lost in its excretion.
It's a good point, but the conversion of ammonia into urea already saves some water because ammonia itself would require much more water for its removal due to its toxicity.
0
tangsiuje
Badges: 2
Rep:
?
#4
Report 13 years ago
#4
My bio teacher said we should think about it as a trade-off between a variety of factors, such as toxicity, water solubility, need of water conservation, energy required for production, etc.

Uric acid might be less toxic than urea, but why would we waste energy in producing it if water is available for excretion?! For birds, low body weight and water conservation is top priority (enabling long-distance flights) --> there is a use of producing uric acid.

Thus, mammals secreting urea is not necessarily inefficient.
0
OldakQuill
Badges: 4
Rep:
?
#5
Report 13 years ago
#5
Therefore:

Name: Ammonia | Urea | Uric acid
Relative toxicity: High | Medium | Low
Energy required: Low | Medium | High
Water lost*: High | Medium | Low
Solubility: High | Medium | Low

*Water is required to dilute toxic substances, it is irrelevent in terms of fish.
0
X
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Cardiff Metropolitan University
    Undergraduate Open Day - Llandaff Campus Undergraduate
    Sat, 27 Apr '19
  • University of East Anglia
    Could you inspire the next generation? Find out more about becoming a Primary teacher with UEA… Postgraduate
    Sat, 27 Apr '19
  • Anglia Ruskin University
    Health, Education, Medicine and Social Care; Arts, Humanities and Social Sciences; Business and Law; Science and Engineering Undergraduate
    Sat, 27 Apr '19

Have you registered to vote?

Yes! (551)
37.84%
No - but I will (114)
7.83%
No - I don't want to (102)
7.01%
No - I can't vote (<18, not in UK, etc) (689)
47.32%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise