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 Lauric Acid in Coconut Oil  



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Author16 Posts
  #1

Pt has coconut oil which is rich in lauric acid (a 14 C saturated FA). What's the net energy yield in high-energy P bonds for a molecule of lauric acid?

A)83
B)86
C)95
D)98
E)112

Please explain how you got to the conclusion. Thnx!




  #2

112 ATP.

I have a formula.

We already knew from WW-Biochem that 16 (satured) FA produces 129 ATPs, 14 FA = 129 -17, 12FA=129-2x17, 10FA=129-3x17, 18FA=129+17, 20FA=129+2x17

But if starts with FA-CoA, all should include 2 more ATPs
14FA-CoA = 131-17
16FA-CoA = 131
18FA-CoA= 131+17

Sure, I am talking about satured FAs.


  #3

Black Tulip,
I saw this question on qbank and of course I got it wrong. I tried to look at their explanation but I couldn't get anything out of their big fat jumble of words.
However, their answer is C; the other choices I changed them a bit cuz I didn't want to get in trouble with any possible law I am not aware of grin

So, I will try to look it over again tomorrow on qbank and if I get any explanation that I understand myself grin, I will post an explanation.
Thnx!


  #4

How is the answer C (95)?

I come up w/ 112 ATP also, I don't understand!


  #5

Ok guys, this is per Kaplan, not per Bela smiling face

Laurate + CoA + ATP :arrow: Lauryl-CoA + AMP + PPi---------(-1 P bond
PPi + H20 :arrow: 2Pi -----------------------------------------(-1 P bond
Lauryl CoA + 5 CoA :arrow: 6 Acetyl CoA----------------------+25 P bond
6 Acetyl CoA + 12O2 :arrow: 12 CO2 + 6H2O + 6 CoA--------+72 P bond
--------------------------------------------------------Total: 95 P bonds

Apparently, to activate laurate, you need 2 high E bonds (ATP-->AMP). Then, the 12 C lauryl CoA is split into 6 Acetyl CoAs. 5 ATPs (from 1FADH2 and 1 NADH) are produced by each b oxidation cycle. Then, the 6 Acetyl CoA each produce 12ATPs from the TCA.

Does it make sense??? You're more than welcome to comment or put down ur own explanation cuz I wanna be able to score some points even on ridiculous qs like this, which seems so complicated to me.


  #6

"Bela" wrote:
Pt has coconut oil which is rich in lauric acid (a 14 C saturated FA). What's the net energy yield in high-energy P bonds for a molecule of lauric acid?

A)83
B)86
C)95
D)98
E)112

Please explain how you got to the conclusion. Thnx!


FORMULA FOR EVEN # C FATTY ACID:
n= # of Carbons
# of Acetyl CoA in an even FA= n/2 (since Acetyl CoA is a 2C molecule)
# of cycles needed to degrade the FA into FINAL 2C= n/2-1

ok with that in mind were now ready to compute:
For 14 C:
To activate FA to Fatty Acyl CoA= negative2 ATPs (2ATPS used up)
Oxidation of 7AcetylcoA= 7 x 12 = +84
Oxidation of 7NADH = 6 x 3= + 18
oxidation of 7FADH2= 6 x2= + 12

Its 114-2= 112

Its really 112ATPs i believe.


  #7

:cry: plz clarify us what is the correct method of calculation and whats the answer.

Thanks...


  #8

Ummm--isn't lauric acid 12:0, not a 14 C saturated FA?


  #9

"Cherry Lav" wrote:
Ummm--isn't lauric acid 12:0, not a 14 C saturated FA?

THATS IT! your right! Lauric is 12C, while Palmitic is 16 C. MYRISTIC is 14 C!!!

So maybe its a typo error in Kaplan.
By the way, my source for this fatty acids name is Harper-Biochem.

let me add that:
12C-Lauric is used in spermaceti, cinnamon,palm kernel, coconut oils,laurels

14C-MYRISTIC-found in nutmeg, palm kernel, coconut oil,myrtles

16C-Palmitic & 18C Stearic are found in in plant and animal fats.
20C-Arachiidic-Peanut oils
22C-Behecic- Seeds
24C-Lignoceric-Cerebrosides and peanut oils

So there-Bela, i think Kapalan had a typo error regarding that 14C. Its actually a 12C Lauric that they used to compute so using the same formula i gave before-it will come up with 95 net ATPS from 12C fatty acid! :wink:


  #10

"Bela" wrote:
Ok guys, this is per Kaplan, not per Bela smiling face

Laurate + CoA + ATP :arrow: Lauryl-CoA + AMP + PPi---------(-1 P bond
PPi + H20 :arrow: 2Pi -----------------------------------------(-1 P bond
Lauryl CoA + 5 CoA :arrow: 6 Acetyl CoA----------------------+25 P bond
6 Acetyl CoA + 12O2 :arrow: 12 CO2 + 6H2O + 6 CoA--------+72 P bond
--------------------------------------------------------Total: 95 P bonds

Apparently, to activate laurate, you need 2 high E bonds (ATP-->AMP). Then, the :?: 12 C lauryl CoA :?: is split into 6 Acetyl CoAs. 5 ATPs (from 1FADH2 and 1 NADH) are produced by each b oxidation cycle. Then, the 6 Acetyl CoA each produce 12ATPs from the TCA.

Does it make sense??? You're more than welcome to comment or put down ur own explanation cuz I wanna be able to score some points even on ridiculous qs like this, which seems so complicated to me.


*********************
Here Pela mentioned that Laurate is a 12C but NOT 14C, so that 's why the answer is 112-17=95[/b]


  #11

u're good step1taker, thanks for that information :icon_salut:


  #12

Thnx guys!

I hope it was a typo in Kaplan but they said it's a 14 C FA and it's found in coconut milk.


  #13

For 14 C:
To activate FA to Fatty Acyl CoA= negative2 ATPs (2ATPS used up)
Oxidation of 7AcetylcoA= 7 x 12 = +84
Oxidation of 7NADH = 6 x 3= + 18
oxidation of 7FADH2= 6 x2= + 12
hi step1taker,
there are 7 molecules of NADH and FADH in ur calculation,but why did u multiply the no of ATPs by 6 rather than 7.and as ur answer is turning out to be correct,i cant figure it out.please,explain it to me:?


  #14

Ey sorry Anne. smiling face
in 14C there is 7Acetyl Coa, 6FADH2, 6NADH produced.
Thats why I multiplied 6x3 (NADH) and 6x2(FADH2).

IN CASE ur wondering ...
Why 6?
Only 6NAD, and 6FADH2 are produced (not7) because only 6 cycles of FA oxidation are needed to reduce a 14C to a final Acetyl Coa.

i.e 14C(LAuric)->12->10->8->6->4->2C(Acetyl CoA)
notice that there are only 6 arrows-meaning 6cycles of FA oxidation to reduce 14C to 2C which is Acetyl CoA.

I hope this is clear thanks for the reminder :wink:


  #15

thanx a great deal!!!


  #16

My head is spinning like a top looking at all these figures!!!!!!!!!HELP!!!!!!!!!!!!!!

1)How does one calculate ATP from a fattyacid,glucose and protein????
2)What is the net usage/production of ATP from a biochemistry cycle??





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