Question

How many molecules of ATP are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)20CO2H?

Answer 1

Answer:

$148~ATP$

Explanation:

In case, we can start with the structure of $CH_3(CH_2)_2_0CO_2H$. When we draw the molecule, we will obtain a total amount of 22 carbons. So, in order to calculate the total amount of ATP we have to make several questions:

How many Acetyl CoA is produced?

To calculate the total Acetyl Coa we have to use the equation:

$Number~of~Acetyl~Coa=\frac{n}{2}$, where n is the amount of carbons, so:

$Number~of~Acetyl~Coa=\frac{22}{2}=11~carbons$

How many rounds take place?

To calculate the rounds we have to use the equation:

$Number~of~rounds=\frac{n}{2}-1$, where n is the amount of carbons, so:

$Number~of~Acetyl~Coa=\frac{22}{2}-1=10~carbons$

How many $FADH_2$ and $NADH$ are produced for this fatty acid?

For each round, we will have 1 $FADH_2$ and 1 $NADH$, if we have 10 rounds. In total, we will have 10

How many ATP are formed?

The ATP would be formed in the electron transport chain and each coenzyme will have a different yield of ATP. So for the total calculation, we have to keep in mind the following relationships:

-) $1~FADH_2~=~1.5~ATP$

-) $1~NADH~=~2.5~ATP$

-) $Acetyl~CoA~=~10~ATP$

So, know we can do the total calculation:

$(10*1.5)+(10*2.5)+(11*10)=150$

We have to subtract  "2 ATP" molecules that correspond to the activation of the fatty acid, so:

$150-2=148~ATP$

In total, we will have 148 ATP.

See figure 1

I hope it helps!