FOM 3.1.2 Flashcards
What molecules carry electrons released in the beta-oxidation pathway?
NADH and FADH2
Beta oxidation converts fatty acids into?
Acetyl CoA
Three macromolecules from diet that can be a source of fatty acids are?
Triacylglycerols, glycerophospholipids, and free FAs
What two fatty acids are required in the diet? And how are these numerically designated?
Omega 3 and Omega 6 fatty acids
They are counted from the omega end and wherever the double bond is that is where is designated
Is this fatty acid cis or trans?
It is Cis
How are most fatty acids in nature arranged?
Fatty acids tend to be unbranced in nature and have an even number of carbon groups
Do cis or trans fatty acids tend to be favored in a diet and why?
The cis form is favored in almost all unsaturated fats occuring in nature. Trans-fats only began to be used once in the food industry.
Side note: it is thought that the cis unsaturated bonds are not able to pack as tightly hence
What specific type of adipose tissue serves as a store for long-chain fatty acids?
White adipose tissue
At rest most other tissues other than the brain prefer to use what as an energy source?
Fats!
Fatty acids are catabolized by what cellular compartment?
Mitochondrial matrix
What is a fatty acid first converted into before being catabolized?
Fatty acyl CoA
How many ATP equivalents are used in “activation” of the fatty acids?
The first step is to take the free fatty acid have it undergo a reaction carried out by Acyl-CoA synthetase. This then creates AMP and Acyl-CoA. The ATP is utilized twice (ATP –>ADP and ADP –> AMP) and thus utilized two equivalents of ATP
How is the acyl-CoA transported from the cytosol to the mitochondria?
It is transferred by a carnitine carrier protein. Carnitine reacts with the acyl-CoA on the cytosolic side yielding acyl-carnitine. It then transverses the inner mitochondrial membrane and reacts with H-SCoA, yielding acyl-CoA in the mitochondrial matrix
What is the regulatory mechanism that cells use to prevent energy waste during synthesis and catabolism?
The cells use compartmentalization. Catabolism is occurring in the matrix and synthesis is occurring in the cytosol
What is the process by which FA transfer into the mitochondria is regulated?
This first step in regulating the transfer of FA entry into the mitochondria is the conversion of Acetyl-CoA to Malonyl-CoA by the enzyme Acetyl-CoA carboxylase. Malonyl-CoA will then go and turn off the transfer of carnitine transferase so that acyl-CoA will stay in the cytosol
What will happen to the transfer of fatty acids to the mitochondria in a scenario with high glucose?
High levels of glucose will lead to the creation of malonyl-CoA, which will then shut off the carnitine transporter and acyl-CoA is not transferred to the mitochondrial matrix.
What happens to the transport of FAs into the mitochondria during a period of high fat?
There is not enough sugar to create malonyl-CoA, thus it is not created and does not inhibit carnitine transferase. Acyl-CoA is tranported into the mitochondria.
What are the type of chemical reactions that are carried out by NADH and FADH2 in beta-oxidation?
These carry out redox reactions
How do cells deal with differing length of FA chains?
Different isozymes account for the differing sizes of FAs.
After one round of Beta-oxidation the cell is left with one acetyl-CoA and one Fatty acyl-CoA. What is the fate of the fatty acyl-CoA?
It is brought right back to the beginning to go through another round of beta-oxidation.
What is the process of dealing with an unsaturated fatty acid with an unsaturation between the alpha and beta bonds?
No change is needed to deal with this. There is just no FADH2 created during the first step of oxidation.
What is the process by which a cell deals with a fatty acid that has an unsaturation on the other side of the beta-carbon?
These go through a modified first step and Enoyl-CoA isomerase moves the double bond between the alpha and beta carbon. This still does not produce any FADH2 because there is no needed oxidation step.
If one molecule is reduced in a redox reaction the what must happen somewhere else?
Oxidation must be occuring somewhere else
What are the amount of calories from FAs, proteins, and carbs?
FA-9
Prot-4
Carbs-4
Catabolism is said to be what?
What is anabolism said to be?
Catabolism - said to be oxidative, substrates lose reducing equivalents, usually H- ions.
Anabolism - said to be reductive, NADPH provides the reducing powers for the building process.
What is the mechanism by which acetyl-CoA is transported out of the mitochondria?
Acetyl-CoA reacts with citrate synthase yielding citrate. This citrate is transported out by the tricarboxylate system. The cytosol then usus this citrate for various things.
Where is another place that the acetyl-CoA from beta-oxidation can be used?
The TCA cycle
What are possible fates for the co-factors used in beta-oxidation?
FADH2 and NADH can use the electrons they took from here and use them in the electron transport chain.
What is the fate of an odd chain fatty acid?
After all the possible rounds of beta-oxidation, the cell will be left with propionyl-CoA. This will be converted into succinyl-CoA and used in the citric acid cycle.
During periods of starvation what does the brain use for energy as an alternative source?
In the liver, Acyl-CoA is converted into ketone bodies (acetoacetate and 3-hydroxybutyrate). These are then used for energy in the brain as well as the kidneys and muscle.
How many ATP are yielded from one 16 carbon chain FA?
The FA will go through 7 rounds of beta-oxidation. Which will result in the generation of 8 acetyl CoA units. It will also generate 7 NADH and 7FADH2.
12 x 8 =96 (Acetyl CoA)
7 x 3 = 21 (NADH)
7 x 2 = 14 (FADH2)
131 - 2 (For the first step in “activation”) = 129 Total ATP
