Questions tagged [metabolism]

Metabolism is the set of defined biochemical transformations occurring within the cells of living organisms.

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Do quantum mechanical effects such as uncertainty, tunnelling and entanglement play role in the electron transport system of respiration?

The electron transport system of aerobic respiration involves an extensive pathway of electron and proton transfer from one centre to another. Now, since they are quantum mechanical particles, shouldn'...
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Are there any known microbes capable of living in almost pure carbon dioxide?

Some bioengineering is investigated in high carbon dioxide environments. Are there any microbes like bacteria or Archaea capable of living and multiplying in such environments?
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Why hypothyroidism causes body ache?

In the condition of hypothyroidism the Thyroid Stimulating Hormone level is high in individuals. What signalling/metabolic pathway mediates this sensation of pain which is mostly experienced in feet ...
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In ketogenesis, why is acetacetyl-CoA not directly hydrolized to acetoacetate in ketogenesis?

Ketogenesis pathway maps show acetoacetyl-CoA converted to HMG-CoA and only then to the first ketone body acetoacetate. Why this detour instead of directly hydrolyzing off the CoA to get there in a ...
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Is there a function for urea in sweat?

In ureotelic organisms, ammonia is converted to urea for excretion primarily in the liver and, to a lesser extent, in the kidneys. However, sweat also contains trace amounts of urea. Is this small ...
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Why does ATP act as an allosteric inhibitor of glycogen synthase?

Why is ATP an allosteric inhibitor of glycogen synthase? Wouldn't high levels of ATP in the cell mean that the cell has sufficient energy, and in this case wouldn't excess glucose be stored as ...
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How is the glycemic index computed from a blood sugar curve?

The definition of the glycemic index is often given as the area under curve (AUC) of their two-hour blood sugar response. However, it's essentially meant to be a measure of whether food causes a fast ...
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How does exercise cause weight loss if the corresponding chemical reactions have the same mass on the LHS and the RHS?

How does weight loss take place in the body during physical activity, given that the corresponding chemical reactions would have the same mass on the left hand side and the right hand side?
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Could the Warburg effect be used to starve cancer cells in situ?

What is wrong with the following chain of reasoning? Nearly all cancer cells rely on high rates of glucose uptake (upto 200 times more than normal cells). This is known as the the Warburg effect. ...
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Isolated mitochondria in glucose rich solution, what happens to ATP generation?

I'm taking intro to biology course this year, and I was thinking about this question. Isolated mitochondria were placed in a glucose rich solution. (With ADP and Pi). How would this affect the ATP ...
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Concentration of active ingredient

For some time now, I have been wondering why, when a tablet is taken, the concentration of active ingredient undergoes an exponential decrease after the maximum concentration value in the blood is ...
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How to determine the actual flux in the human metabolic model of a cell line?

The problem to be solved is to determine what the flux values are for the different reactions in the human metabolic model. As far as I understand, a good way to do that would be to use gene ...
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What is a flux control coefficient?

In metabolic control analysis, a number of coefficients are defined, including the flux control coefficients. How is this coefficient defined and what does it measure?
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Why is fructolysis independent of glycolysis?

In glycolysis, glucose is converted to fructose-6-phosphate before further breakdown. However fructose, instead of being phosphoryated to fructose-6-phosphate by glucokinase (and thereafter to ...
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What actually kills a plant that requires winter dormancy if it is kept indoors all year?

In bonsai practice, beginners will commonly purchase a juniper (often Juniperus procumbens 'Nana'), which is an outdoor tree, and keep it inside all year. The tree invariably dies. It is commonly ...
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What are the effects of caffeine on the mammalian circulatory system?

A friend of mine told me an anecdote about his mother, who drank too much caffeine, to the point she became hypotensive and would pass out. Because caffeine acts as a stimulant, I'm assuming the ...
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What is the biological mechanism underlying caffeine intolerance? (CYP1A2 or other?)

As far as I can tell, caffeine metabolism occurs primarily via the CYP1A2 enzyme. I am curious as to whether mutations in the CYP1A2 gene are associated with caffeine intolerance. Some site that is ...
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Production of plant derivatives using genetic engineered micro-organisms

I saw a Thought Emporium video where spider silk was produced by genetically modifying yeast. I have also read about companies making vanillin (vanilla flavour) using this technique. I am curious to ...
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Maximum Allometry of aquatic mammals omitting Kleiber's Law

As far as I understand, blue whales cannot get any physically larger due to the extremely demanding caloric intake it has on consuming large quantities of krill, not due to any other physiological ...
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Pyruvate dehydrogenase: Apparently anomalous NAD/FAD redox reaction

Below is the mechanism for the reactions of the pyruvate dehydrogen complex, which oxidatively decarboxylates pyruvate and transfers the acetyl group to coenyzme A for further metabolism in the Krebs ...
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What terms or concepts are used to describe the morning metabolic phenomenon involving glucocorticoids, glucose, and blood pressure?

A recent conference report described using a vaccine-based strategy to blunt a surge of high blood pressure that occurs between 5 and 8 a.m. Apparently most heart attacks and strokes occur during ...
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Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle? I originally thought that Krebs cycle was aerobic metabolism ...
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Why is transferrin saturation so low?

Transferrin Saturation (TS) is a common laboratory test and its values can be used to diagnose a variety of medical conditions. In healthy humans, and I assume it is the same for other species, TS is ...
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How do cellular conditions change the Gibbs free energy of a reaction?

How do cellular conditions change the Gibbs free energy of a reaction? Taking glycolysis as an example, how exactly would cellular conditions affect the free energy released from this reaction?
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Why does NAD+ become reduced if it gains a hydrogen proton?

I've heard that $\ce{NAD^+}$ gains a Hydrogen proton during glycolysis and the Krebs cycle and becomes reduced to $\ce{NADH}$. However, isn't reduction when a molecule receives an electron? Maybe I'...
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Why is the brain dependent on glucose?

The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood ...
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Why/How do Cyanobacteria Produce Toxins?

I've been doing some research on the versatility of nitrogen-fixing cyanobacteria, particularly of the genus Anabaena, and I often run into safety hazards and have to add extra steps to my procedures ...
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What is the energetic costs in KJ/g NH3 for nitrogenase fixation

What is the energetic costs in KJ/g NH3 for nitrogenase fixation. I want to compare Haber-Bosch vs nitrogenase. How would I force the biological stochiometry of 8e- electrons into an energy quantity. $...
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Do all anabolic reactions involve condensation?

I know that condensation is one example of an anabolic reaction (building macromolecules from monomers), but do all anabolic reactions involve condensation? Or is there an example of an anabolic ...
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Can you change your gut microbiota by changing your diet? Would that affect calorie uptake?

I have seen peer-reviewed papers mentioning the daily changes in gut microbiota composition according to dietary changes. See for example this paper: http://genomebiology.com/2014/15/7/R89 My ...
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What is a metabolite? [closed]

I am a mathematician and work on metabolic networks as networks. But I could not find a proper definition for a metabolite? Are they organic molecules? can a gene or a protein also be a metabolite?
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Relation/difference between metabolism and cellular organisation

In the highlighted paragraph from NCERT textbook, they mention that cellular organisation is the defining property of life forms while metabolism without exception is also the defining property of ...
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How much ATP formed from oxidation of stearic fatty acid

Stearic fatty acid is a C18-molecule, so eventually 9 acetyl-CoA molecules will be formed. One acetyl-CoA molecule enters the citric acid cycle, resulting in 3 NADH & 1 FADH2. Because there are 9 ...
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Apparent paradox in Glucagon action

Glucagon stimulates glycogenolysis and gluconeogenesis, thus increasing the plasma glucose concentration — so that tissues get enough glucose in the fasting state. However glucagon also inhibits ...
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Do Termites and Silverfish metabolize cellulose the same way?

I am fascinated with silverfish and would like to understand more about their metabolism. I learned that they can survive on a diet of cotton which is nearly pure cellulose. Do they metabolize ...
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Why are children more active than adults?

I have observed that children are usually more active than adults. For example, in the morning they get up and start playing, they have their lunch and get up and start running, while as adults they ...
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Do identical twins have the same metabolism rate at birth? [closed]

Will monozygotic twins defecate at the same time if fed at the same time during the first weeks of life? They should have the same genetics (and epigenetics) since they are monozygotic and the same ...
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Glycogenolysis & Gluconeogenesis

Is glycogenolysis and Gluconeogenesis is the same in the terms of product formed? This doubt arrived when I was attempting true & false and the question was Glucocorticoids stimulate ...
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How does lactulose cause the removal of ammonia from the colon?

Lactulose is also used to reduce the amount of ammonia in the blood of patients with liver disease. It works by drawing ammonia from the blood into the colon where it is removed from the body. [Source]...
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mitochondria has more activity or the numbers of them are more?

If a cell is needing energy more than the other cells, does it mean that it has more mitochondria or the activity of them is more?
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Can bacteria metabolize fatty acids for fuel?

I'm not a microbiologist, but rather a physiologist curious about microbial metabolism. Much like humans bacteria can utilize glucose, but when it comes to long chain, medium chain, or short chain ...
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Would intravenous insulin + glucose significantly accelerate glycogen synthesis?

Would an intravenous injection of insulin + glucose result in significantly quicker replenishment of exhausted glycogen stores than an injection of glucose alone? This is a strictly theoretical ...
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What is the ultimate source of ADP/ATP in humans?

I am teaching myself Cell Biology from the internet. Despite my usually good Googling skills, I'm stuck in a loop with this question. Q: What is the source of ATP? A: ADP Q: What is the source of ...
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Quantification of various amino acids from bacteria?

I would like to characterise how much of various (uncommon) cytosolic amino acids are produced in bacteria, and was wondering if there are good suggestions of how to go about doing this. I know that ...
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Reverse oxidative phosphorylation?

I noticed that all of the cellular energy production methods that I covered have a fixed ratio of ATP to NAD(P)H out. For example, in the combined process of glycolysis, pyruvate oxidization, and the ...
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Should I consider [H+] as substrate in MCT transport equation?

I'm trying to model the transport of lactate in cells (in both direction via Monocarboxylate transporters): [Lactate]intra + [H+] <----> [Lactate]extra + [H+] I found some data on kinetics of ...
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What is the use of futile reaction cycling such as Fruc-P to Fruc-BP?

One rate-limiting step of glycolysis is the conversion of Fructose-6-Phosphate (Fruc-6-P) to Fructose-1,6-Bisphosphate (Fruc-1,6-BP), catalysed by Phosphofructokinase 1 (PFK 1). The reaction involves ...
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How does exercising/starved muscle import glucose (released by liver)?

Adrenaline releases glucose from the liver during sport or if starved. This glucose goes to the blood through GLUT2 transporter. But how does it get transported into the muscle cells? GLUT4 is the ...
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Can muscles remake pyruvate from lactic acid, or does it have to go to the liver in the Cori cycle?

When the muscle is exercising, and only anaerobic respiration is done, pyruvate -> lactate to regenerate NAD+. Lactate is then transported out of the muscle and into the liver, to regenerate glucose, ...
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What relation do glycerol-3-P DH and acyl-CoA DH have with Complex II of the ETC?

I am sorry if this may be a purely definitional/nomenclature question. Complex II of the electron transport chain (ETC) would be succinate dehydrogenase, transporting electrons to ubiquinone (and ...

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