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Fatty acids

I'm trying to work through all the short questions on previous HonMods exams as the breadth of information I seem to be required to know is completely beyond me :frown:

"Briefly describe four differences between higher plants and mammals in the structure, synthesis and metabolic fate of the fatty acid components of triacylglycerol"

Well my first thought is that I'm fairly sure in... now hold on which way round is this... in plants there are more unsaturated bonds? I think that makes sense because that's why you get oils from seeds rather than fats... right? Gah can never remember...

From that point on I'm stuck and Alberts' is being fairly useless grrr

Reply 1

Stranded

I'm just an AS student & here's what I know:
Plants contain unsaturated fatty acids (ex oleic acid) which have got atleast one double bond between thier carbon atoms. Incidentally, they have fewer hydrogen atoms within their chain. In addition, these acids have a lower melting point so are liquids at rtp. As for mammals, they've saturated fatty acids with a higher melting point(ex steric acid). Also, the saturated fatty acids are easily converted to cholesterol than unsaturated ones.

Thats all I know. Hope that helps! :redface:

Reply 2

nikk

I am a human bio student so don't know a great deal about planty stuff...but:

(1) Plant derived FA tend to be much longer than animal FA....and as a result
(2) Many long-chain plant-derived fatty acids are oxdised in peroxisomes because the mitochondria cannot deal with them (I don't know why). The differences are that acyl-CoA oxidase is used to oxidise the FA and produce H2O2 (which has to be detoxified by catalase), and later on in the oxidation cycle, the NADH produced is exported into the cytoplasm. Hence oxidation of long-chain FA such as those from plants don't lead to ATP production, but do release heat (I assume such oxidations are implicated in maintaining body temperature).

Sorry if I have waffled a bit, but those are the main two differences I know.

Reply 3

Tom H

I'm seriously glad I'm not doing Biochem at Oxford. The one thing I hate above all else is metabolism. So many pathways, so many enzymes, so many regulatory elements... it melts my brain!

Reply 4

Jenski

Plants have unsaturated fats as they need to have the fats as liqids as plants can't heat themselves. Warm blooded animals can have saturated fats as their higher body temp allows the fats to be liquid (so they can be transported). Fish living in cool waters have loads of unsaturated fats for the same reason as plants.

No idea if that helps or not!
:smile: