Fatty Acid Metabolism Flashcards
How are Fatty Acids named?
Either alpha, beta convention (start near carbonyl)
or
omega convention (start at end). Ex omega 3 FAs have a double bond from 3-4 carbon from the end.
Most fatty acids have an even number of carbons. (#carbon:#double bond) .
Describe the structure of palmitate.
Palmitate is a saturated fatty acid with 16 carbon atoms and no double bonds, represented as (16:0).
Define unsaturated fatty acids.
Unsaturated fatty acids contain one or more double bonds between carbon atoms, which can affect their physical properties.
How does the presence of double bonds affect the melting point of fatty acids?
The melting points of fatty acids are generally higher if they have longer carbon chains and are saturated, while unsaturated fatty acids tend to have lower melting points.
Explain the difference between cis and trans fatty acids.
Cis fatty acids
Have hydrogen atoms on the same side of the carbon double bond, which causes the carbon chain to kink. Cis fatty acids are found in natural foods like nuts, fish, and corn oil. They are generally considered beneficial for human health because they can help keep the heart healthy.
Trans fatty acids
Have hydrogen atoms on opposite sides of the carbon double bond, which makes the fat more linear and rigidly packed. Trans fatty acids are mostly created during the hydrogenation process, which stabilizes polyunsaturated oils to keep them solid at room temperature. They are not essential and have no known health benefit. Trans fats are typically found in hydrogenated oils.
Trans fats can raise “bad” cholesterol and lower “good” cholesterol, which can increase the risk of heart disease. The more trans fats eaten, the greater the risk of heart and blood vessel disease.
What is the significance of polyunsaturated fatty acids?
Polyunsaturated fatty acids have multiple double bonds that are typically three carbons apart, which can influence their health effects and physical properties.
How does the carbon chain length affect the properties of fatty acids?
Longer carbon chains in fatty acids generally lead to higher melting points and can influence their physical state at room temperature.
Define saturated fatty acids and provide an example.
Saturated fatty acids have no double bonds between carbon atoms. An example is stearic acid, represented as (18:0) with 18 carbon atoms.
Describe the impact of trans fatty acids on health.
Trans fatty acids are considered bad for cholesterol levels and can increase the risk of heart disease.
What is the chemical representation of oleate?
Oleate is an unsaturated fatty acid with 18 carbon atoms and one double bond, represented as (18:1).
Explain the notation used for fatty acids, such as (16:0) or (18:1).
The notation indicates the total number of carbon atoms followed by the number of double bonds in the fatty acid.
Define triacylglycerols.
Triacylglycerols, also known as triglycerides, are a type of fat found in the body, primarily stored in adipose (fat) cells.
They are composed of 3 fatty acids and glycerol esterified together.
Describe the energy content of triacylglycerols compared to glycogen.
Fatty acids are considered more reduced than glycogen because their carbon atoms have more hydrogen bonds and fewer oxygen atoms compared to the carbon atoms in glycogen, meaning they have a greater potential to release energy when oxidized during metabolism; essentially, fatty acids have a higher “reduction state” due to their chemical structure, allowing them to store more energy per gram than carbohydrates like glycogen
Triacylglycerols are more reduced so they provide more energy than glycogen, offering 9 kcal/g compared to glycogen’s 4 kcal/g.
How do triacylglycerols differ from glycogen in terms of water content?
Triacylglycerols contain no water, while glycogen has a water content of 2:1 water to glycogen.
Explain significance of the ratio of triacylglycerols to glycogen in energy storage.
15 kg of triacylglycerols can provide the energy equivalent of 90 kg of glycogen, highlighting the efficiency of fat as an energy storage form.
Fatty Acid Degradation vs Synthesis, which is more significant and common?
Degradation because we have energy needs every day. The fat we eat daily gets degraded and used as energy. Synthesis only occurs if there’s excess.
What role do lipases play in the metabolism of triacylglycerols?
Lipases are enzymes that break down triacylglycerols into glycerol and fatty acids, facilitating their use as energy.
How does insulin influence the synthesis of triacylglycerols?
Insulin inhibits lipases to decrease Fatty Acid Degradation
Insulin promotes the synthesis of triacylglycerols, aiding in fat storage and energy regulation.
Describe the relationship between epinephrine, glucagon, and triacylglycerol metabolism.
Epinephrine and glucagon stimulate lipases to break down triacylglycerols, promoting the release of fatty acids for energy use. They also inhibit FA synthesis.
Think: When you’re fasting and run out of glucose, you’re body breaks down fat.
What is the significance of glycerol in energy metabolism?
Glycerol can be converted into dihydroxyacetone phosphate (DHAP), which can enter glycolysis or gluconeogenesis, contributing to energy production.
How are fatty acids transported to the liver and muscle tissues?
Fatty acids are transported to the liver (and muscle tissues) by serum albumin, a protein that binds to fatty acids in the bloodstream.
Explain the process of fatty acid activation before entering the mitochondrial matrix.
Fatty acid activation involves the conversion of fatty acids into acyl-CoA using ATP, which prepares them for subsequent metabolism in the mitochondrial matrix.
A synthestase is an enzyme that uses ATP. Synthase doesn’t need ATP generally.
How does beta-oxidation contribute to energy production?
Beta-oxidation is the process by which fatty acids are broken down in the mitochondrial matrix to produce acetyl-CoA, NADH, and FADH2, which are used in the citric acid cycle and oxidative phosphorylation for ATP production.
How does acyl-CoA enter the mitochondrial matrix?
Acyl-CoA enters the mitochondrial matrix by first being converted to palmitoyl-carnitine through the action of carnitine palmitoyl transferase I, allowing long-chain fatty acids to cross the mitochondrial membrane.
Define the role of carnitine in fatty acid metabolism.
Carnitine facilitates the transport of long-chain fatty acids into the mitochondrial matrix by forming palmitoyl-carnitine, which can cross the mitochondrial membrane.
What inhibits the transport of long-chain fatty acids into the mitochondrial matrix?
The transport of long-chain fatty acids into the mitochondrial matrix is inhibited by malonyl-CoA, which is a product of fatty acid synthesis.
This is a form of negative feedback regulation
Do short and medium-chain fatty acids require carnitine for mitochondrial entry?
No, short and medium-chain fatty acids can enter the mitochondrial matrix directly without the need for carnitine.
How can muscle pain and weakness be related to carnitine palmitoyl transferase II deficiency?
Muscle pain and weakness can occur due to the inability to properly metabolize fatty acids, leading to energy deficits in muscle cells, which may result in rhabdomyolysis.
Define rhabdomyolysis and its potential consequences.
Rhabdomyolysis is a condition characterized by the breakdown of muscle tissue, releasing myoglobin into the bloodstream, which can lead to kidney damage and other serious complications.
Describe the steps of beta oxidation. Keep it simple.
Beta carbon on the fatty acid is oxidized into a carbonyl then cleaved to remove 2 carbons as Acetyl coA, which can enter TCA and oxidative phosporylation. This repeats until all carbons are used up.
Here is a more detailed image of the beta oxidation mechanism. What is the name of the enzyme that catalyzes the first oxidation? The last step is not a hydrolyis but a ________.
Acyl CoA dehydrogenase; Thiolysis
Describe the role of ketone bodies in the body. Why not just send acetyl-CoA into bloodstream?
Ketone bodies serve as transportable forms of Acetyl-CoA, primarily produced by the liver, and are utilized by various tissues such as brain, muscle, renal cortex, and heart (prefers them to glucose), especially during fasting and starvation.
Acetyl-CoA cannot directly travel through the bloodstream because of its large, highly reactive structure, so when the body needs to transport energy from fatty acid breakdown, it converts acetyl-CoA into ketone bodies, which are smaller and more readily cross the blood-brain barrier, allowing them to be used as an energy source by other tissues when glucose is low.
Fatty acid synthesis occures in the cytoplasm and requires Acetyl-CoA, which can not pass through membranes. How do we get Acetyl-CoA out of the mitochondrial matrix and into the cytoplasm?
Acetyl-CoA combines with OAA to become citrate (think TCA), move into the cytoplasm, then converted back so it can be used.
A lot of NADPH is needed to make fatty acids (anabolic). How is NADPH generated during the process of fatty acid synthesis?
NADPH is generated through the action of the malic enzyme, which converts malate to pyruvate, producing NADPH and CO2 in the process.
The first step of fatty acid synthesis is the activation of Acetyl-CoA. Which enzyme catalyzes this rxn and what is formed?
Acetyl CoA Carboxylase uses CO2 to add a carboxyl group to Actetyl CoA. Biotin is involved as a Co2 donor. This forms malonyl-CoA.
Describe the process of converting acetyl-CoA to palmitoyl-CoA.
The conversion involves the sequential addition of two-carbon units from malonyl-CoA to the growing fatty acid chain, ultimately producing palmitoyl-CoA.
