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Oh my god, this has confused me for months and I finally think I get it, so I hope I can explain it decently. When fatty acids are oxidized, the acetyl-CoA can enter the Krebs cycle, and one would think that the oxaloacetate generated by the Krebs cycle could be converted to acetyl-CoA, which could then be converted to pyruvate for gluconeogenesis. This can't happen, though, because even though oxaloacetate is made, there is no net increase in oxaloacetate (two carbons are lost in the Krebs cycle for every two in the acetyl-CoA coming in). Oxaloacetate can't be taken out of the cycle, then, because then the cycle would be depleted and the only way to replenish it is through one of the anapleoritic reactions, which involve products of glycolysis (PEP and pyruvate). If there is enough PEP or pyruvate around to replenish the oxaloacetate you're taking out to make glucose, chances are you don't need to make glucose in the first place. Pyruvate from glucose or amino acids can be used to make sugars before it is converted to acetyl-CoA, but the pyruvate dehydrogenase complex reaction is irreversible, so once pyruvate is made into acetyl-CoA it cannot be used to make glucose; it is committed to either fatty acid synthesis or the Krebs cycle. Plants can make glucose from fatty acids, but this is only because they are able to use the glyoxlyate cycle instead of the Krebs cycle. The glyoxylate cycle bypasses the step in the Krebs cycle (the alpha-ketoglutarate dehydrogenase step) in which the two carbons are lost as CO2, so when plant acetyl-CoA enters the glyoxylate cycle there IS a net increase in oxaloacetate which can be used to make pyruvate.
What else can I help you with?
Into what body fluids do glucose fatty acids amino acids pass?
Glucose, fatty acids, and amino acids pass into the bloodstream.
Glucose molecules are to starch as what are to lipids?
This is an analogy between the molecular components of two different macromolecules. Glucose molecules compose starch, and its correspondent to proteins would be amino acids to solve this question.
What are the final end products for carbohydrates lipids and proteins?
Carbohydrates: Glucose Lipids: Fatty acids and glycerol Proteins: Amino acids
What are fatty acids converted to in Beta-oxidation?
Fatty acids are converted into acetyl-CoA molecules during beta-oxidation. Acetyl-CoA is a crucial molecule in the citric acid cycle (Krebs cycle) which generates energy through the production of ATP.
Can long-chain fatty acids be absorbed directly into the blood?
No, long-chain fatty acids are broken down into smaller molecules called monoglycerides and free fatty acids in the small intestine before they can be absorbed into the bloodstream. They are then reassembled into triglycerides and packaged into chylomicrons for transport.
Which of the following compounds cannot be converted to glucose?
Fatty Acids.
Into what body fluids do glucose fatty acids amino acids pass?
Glucose, fatty acids, and amino acids pass into the bloodstream.
Approximately what percentage of triglycerides CANNOT be converted to glucose?
Approximately 10-15% of triglycerides cannot be converted to glucose. These triglycerides are primarily stored in adipose tissue and are used for energy production through beta-oxidation in the liver, rather than being converted to glucose.
What cannot be used to form new glucose in the body?
Fatty acids cannot be used to form new glucose in the body because they are molecules made up of carbon and hydrogen, which cannot be converted to glucose through the process of gluconeogenesis. Instead, fatty acids are broken down through beta-oxidation to produce energy in the form of ATP.
What is a product of the Calvin cycle that is used to form glucose phosphate amino acids or fatty acids?
A key product of the Calvin cycle is glyceraldehyde-3-phosphate (G3P), which serves as a precursor for forming glucose, phosphate, amino acids, and fatty acids. G3P can be converted into glucose through a series of enzymatic reactions, and it can also be utilized in the synthesis of various organic molecules needed for plant growth and metabolism.
When needed for a source of energy fatty acids are broken down in glucose?
fat is broken down into fatty acids
What is the end product of fat and oil?
The end products of fat digestion are fatty acids and glycerol.
Where does glucose go when it leaves the small intestine?
After leaving the gut, the liver is the first tissue to use dietary glucose. In the liver, glucose can be converted to glycogen to be stored or distributed through out the body for energy. It can also be converted to fatty acids. The conversion of glucose to fatty acids usually only happens if energy intake has exceeds energy expenditure.
Are fatty acids sub-units of carbohydrates?
No. The sub-units for carbohydrates is a monosaccharide such as glucose or fructose. Fatty acids are what results from the sub-unit aliphatic compounds and glycerol.
Can fatty acids and glycerol be used as sources of energy?
Yes. Fatty acids undergo beta oxidation and make acetyl coA, which goes through the TCA cycle until it reaches oxaloacetate. However, a fatty acid cannot be used to make new glucose. Glycerol can enter glycolysis by being converted into glyceraldehyde 3 phosphate.
When amino acids are deaminated what source can they be used as?
When amino acids are deaminated, the resulting carbon skeletons can be used as energy sources through processes like glycolysis or the citric acid cycle. They can also be converted into glucose, fatty acids, or ketone bodies for energy production or storage.
Can fatty acids be converted to oxaloacetate?
Not directly. Fatty acid β-oxidation results in acetyl CoA, which is then entered to the Citric Acid cycle. The "last" step of the cycle is the formation of oxaloacetate from malate.
