Lipid Metabolism Summary
glycerol reacts with fatty acids to make lipids: Catabolic reactions give out energy. They are exergonic. Metabolism is a combination of two processes: anabolism and catabolism. . Therefore the concentration of circulating FFA increases and lipid becomes A reciprocal relationship between SFA-induced IR in fat/muscle cells. Anabolism and catabolism are metabolic processes. acids, proteins becoming glucose, glycogen becoming glucose, or triglycerides becoming fatty acids.
Glucagon activates a hormone-sensitive lipase, which hydrolizes triacylglycerols yielding glycerol and fatty acids. These are then released into the bloodstream in lipoproteins.
Muscle Muscles use glucose, fatty acids, ketone bodies and aminoacids as energy source. It also contains a reserve of creatine-phosphate, a compound with a high phosphate-transfer potential that is able to phosphorilate ADP to ATP, thereby producing energy without using glucose. The amount of creatine in the muscle is enough to sustain about s of exertion.
After this period, the muscle uses glycolysis, first anaerobically since it is much faster than the citric acid cycleand later when the increased acidity slows phosphofrutokinase enough for the citric acid cycle to become non-rate-limiting in aerobic conditions. Kidney It can perform gluconeogenesis and release glucose into the bloodstream.
It is also responsible for the excretion of urea, electrolytes, etc.
Metabolic acidosis may be increased by the action of the urea cycle, since urea synthesis which takes place in the liver uses HCO3- thereby further lowering blood pH. Under these circunstances, nitrogen may be eliminated by the joint action of kidney and liver: Kidney glutaminase then cleaves glutamine in glutamate e NH3, which the kidney immediately excretes.
This process allows nitrogen excretion without affecting blood bicarbonate levels. Hormone control Hormone control is mainly effected through the action of two hormones synthesized by the pancreas: Insulin is released by the pancreas when blood glucose levels are high, i. Insulin stimulates glucose uptake by the muscle, glycogen synthesis, and triacylglyceride synthesis by the adipose tissue.
So in the case of fats, we're talking about fatty acids, which are the smallest subunits of fats. And then for carbohydrates, which are long chains of sugars.
One of the most common subunits of carbohydrates that our body loves is called glucose. So I'll go ahead and write that here, since you'll be seeing it a lot in the discussion of metabolism.
And then finally, for nucleic acids were talking about nucleotides. So at this point, you're probably thinking, well, OK. I understand that our body can't use the same macromolecules found in food because maybe they're not in the right configuration. But how does breaking them down do anything for us? Now the key here is to recognize that in our body there is actually a delicate balance going on between the processes of breaking down molecules, such as in the process of digestion, and then taking these products and building them back up.
So essentially, you can see all of these subunits, or monomers, as LEGO pieces that we're essentially reconstructing to build the right configurations of proteins, fats, carbs, and nucleic acids that our body needs. So that's really the key idea here, which is that metabolism is a balance between breaking things down and building them back up in our body so that we can customize, so to say, what type of macromolecules that we create.
And just to throw in some vocab words, biochemists call the process of breaking down molecules in our body catabolism.
And similar sounding word called anabolism is used to describe the process of building molecules back up. And the way I like to remember this is looking at the first letter of each of these words, I think of C, I think of cutting molecules up into tiny pieces, so breaking them down.
And then for anabolism, A, I think of as like the apex of a building, for example. So we're building something up. Now this seems all fine and elegant, but there's one more issue that we need to contend with, which is a consequence of having to balance breaking things down and building them back up. And that is that this process of building molecules back up requires energy.
Which I'm kind of indicating here by these yellow lightening bolt stars. At high temperatures molecules have more energy than at lower temperatures. Therefore collisions are more frequent and the likelihood of the molecules having enough energy is greater. Consequently the rate of chemical reactions increases with increasing temperature.
Amino acid synthesis - Wikipedia
Activated complexes and activation energy Some reactions take place in a single step. We can represent this using an energy profile. An activated complex or transition state forms between reactant and product.
This is not a 'real' substance in the sense that it can be isolated and put in a test tube. But based on various pieces of experimental evidence it is the chemist's model of how the reaction occurs. The energy 'hump' shows how much energy reacting molecules must have for a 'successful' collision, i.
- Amino acid synthesis
- Overview of metabolism: Anabolism and catabolism
- Metabolism and energy
The formation of an activated complex requires energy to bring molecules together in the correct orientation. Therefore, it is always an endergonic reaction. The energy required is called the activation energy Ea. After each step a reaction intermediate forms. Unlike an activated complex this has a real existence.
Anabolism and Catabolism | BioNinja
For each step an activated complex is formed and there is an associated activation energy. The step with the highest activation energy is the rate-determining step in the reaction and controls how fast the overall reaction is. Catalysts In chemical factories high temperatures and pressures are often used.