Lipid Metabolism 1.2 Flashcards
What is esterification?
The addition of a acid gras on a glycerol
For example, triple esterification gives you a trigliceride
This can be used as storage of energy
It can then be broken down (lipolyse) to use
What is beta-oxydation?
Degradation of acides gras into Acetyl-CoA for energy
Lipogenese (de novo)
Location, input, 1st and second step, product and key enzymes
Happens in the cytosol:
Need Acetyl CoA, NADPH, ATP (exam)
1st step: Formation de malonyl-CoA
** Acetyl-CoA** + energy +(acetylCoA carboxylase) -> malonyl-CoA
This is out lego block
2nd step: Elongation
(acide gras synthétase) +7 malonyl-CoA-> palmitate
acide gras synthétase is a dimer
acide gras synthétase is a dimer
acide gras synthétase is a dimer
acide gras synthétase is a dimer
exam
Why can you say that it makes sense that lipogenesis needs energy
Lipogenese is often activated by insulin following a meal
That is when we have a lot of energy available so its ok to use some energy in order to store
true or false,
We are capable of synthesizing omega-9 acids
True
From palmatic acid we can only form omega-9
omega-3 and omega-6 cannot be synthesized
Where does beta-oxydation occur?
In the mitochodria
How does beta-oxydation work?
It takes an acide gras
It breaks at the beta bond (2nd carbon) to produce Acety-CoA and NADH that will be used for energy
Depending on the length of the fatty acid, you can have multiple cycles
You have sent two patients for glucose levels and they both have excess increased glucose levels. However, one of them is more urgent, why?
The urgent one might have very low levels of insulin to the point where he might be producting too many ketone bodies and risk acidosis.
One cycle of beta-oxidation should produce 17ATP but instead **sometimes **only gives 15 why?
Chaque cycle génère 17 ATP
* 1 FADH2 = 2 ATP
* 1 NADH = 3 ATP
* 1 acétyl-CoA =12 ATP (via cycle de Krebs)
However, there is a 2ATP investment to activate the fatty acid via acyl-CoA
THis only happens at the begining of the cycle!!!
As such, the rest of the fatty acid will produce 17ATP
How much energy is produced from 1 palmitate breakdown in an oxygen vs non-oxygen environment?
palmitate = 16 carbons
16/2 = 8 Acetyl CoA
and
7FADH
7NADH
-2 for activation
overall: 129ATP
No oxygen = 0ATP
At what time would you increase the level of ketone bodies and why?
On an empty stomach
-> this is because beta-oxydation is increased -> more ketone bodies
insulin of course inhibits this
What is HMG-CoA réductase?
Key enzyme in cholesterol synthesis
It is the ** Étape limitante ** that leads to production of mevalonate from Acetyl-CoA
As such, a medication that blocks this enzyme can block cholesterol production
L’HMG-CoA réductase est l’étape limitante dans la synthèse du
cholestérol
* La synthèse du cholestérol est donc contrôlée par régulation de l’activité de
l’HMG-CoA réductase
Role of ketone bodies?
They can transport Acetyl-CoA in the blood
