The set of biochemical reactions that sustain life by directly or indirectly affecting energy expenditure and/or storage, as well as the complete regulation of those reactions and the enzymes that catalyze them; including, hormonal, cell-signaling, and substrate level regulation.

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Is high metabolism linked to high evolutionary turnover?

I recently read The Dinosaur Heresies by Robert T. Bakker, a 1986 popular science book presenting arguments for an active lifestyle and high metabolic rate in dinosaurs. One of the arguments that ...
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119 views

Why are Mammals are unable to produce Essential Fatty Acids?

Why do we have to get them from our diet, and if they aren't taken in our diet we will face disease? Then why we don't have the enzymes which are require for EFA synthesis?
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19 views

Cellular demand for antioxidants

Antioxidants such as ascorbate and glutathione serve to inactivate radicals and counteract spontaneous oxidation reactions, such as unwanted disulfide bonds in proteins. These systems are cycles, ...
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24 views

Are there animals that can deliberately manipulate their metabolism, apart from hibernation?

Are there animals that can slow down their metabolism deliberately? I know that hibernation would be one mechanism, and maybe being cold-blooded, but I was wondering if there was maybe an animal that ...
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26 views

Are there bacteria that respire anaerobically in aerobic conditions?

There are facultative aerobic bacteria that switch to aerobic respiration in an aerobic state, but are there any organisms that would still perform anerobic respiration even when shifted to aerobic ...
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35 views

Are there any enzymes synthesised by humans that specifically catalyse the hydrolysis of non-cyclic Imides?

Imides or dicarbonyl amides are an interesting class of compounds that includes the pharmaceuticals thalidomide, aniracetam and a few other drugs. These compounds, however, are cyclic and I'm ...
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78 views

Iron metabolism in the brain

I did an expression profiling from publicly available RNAseq data for mouse tissues. While for liver and testes I am getting expected proteins in the top highly expressed mRNAs, for brain I am getting ...
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89 views

Food Intake versus ability to flee among birds, particularly the hummingbird?

Logically speaking, if a hummingbird drinks too much nectar, it will be temporarily overweight and less able or unable to fly to escape danger. However if the same hummingbird doesn't drink enough ...
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26 views

What is the function of CETP?

I read up that CETP transfers cholesterol from HDL, which collected it from tissues, to VLDL. This VLDL is then sent back to the tissues, ultimately forming LDL internalised by cells. What is the ...
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28 views

What is the rationale behind reverse cholesterol transport?

Reverse cholesterol transport is transport of cholesterol from the tissues back to liver/VLDL. My question is why do the tissues have this extra cholesterol in the first place? Why would you ...
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30 views

Why lactate inhibits growth (or enhances death rate)?

Extracellular lactate tends to inhibit cellular growth or enhance cell death. This happens in the vicinity of tumors and in cell cultures. See for example this reference: Ozturk, Sadettin S., Mark ...
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28 views

Metabolic control theory: proof of the summation theorem?

I'm looking for a rigorous proof of the summation theorem of metabolic control theory. The only sources I find are the original papers by Kacser and Burns 1973 and Heinrich and Rapoport 1974, both of ...
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23 views

Which biosynthetic pathways take place in the plastid and were are they located?

I know that the isoprenoid, jasmonate, glucosinolate, fatty acids, chlorophyll, starch, and aromatic amino acid syntheses are located in the plastid. But I don't know if they are located in the ...
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93 views

Does the metabolic rate determine how fast the telomeres shorten?

In many papers one can read that telomeres may play an important role in longevity. According to Calado et al.1 the telomeres of mice are much longer than the telomeres of humans. However, mice have ...
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50 views

Is body energy production and consumption cyclical?

If we look into how energy is produced by the humans, it always involves some kind of periodicity: fuel combustion rotates engines, water rotates turbines, nuclear chain reactions heat up water, which ...
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85 views

Why is a nicotinamide-tryptophan combination used to treat affective episodes in a few older clinical trials?

At least one of the journal articles that reported on such clinical trials allured to the nicotinamide-tryptophan pathway that I assume must be related to the metabolism of tryptophan into serotonin ...
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140 views

Are simple esters like those used as flavouring agents metabolised into their constituent carboxylic acids and alcohols in the human body?

By this I mean to ask whether say ethyl butanoate is hydrolysed in humans into ethanol and butyric (butanoic) acid. This is of interest to me as a pharmacology researcher because butyric acid, for ...
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21 views

Insulin and leptin action on Anorexigenic Neurons in Hypothalamus?

Receptors for Insulin are present on liver, adipose tissue and muscles BUT also Insulin Receptors are present in arcuate nucleus of hypothalamus where it influences anorexogenic neurons through IRS2 ...
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14 views

What's the highest glucose concentration (in mM) anywhere in the human body (tissue, capillaries, tumor microenvironment, etc.)?

Glucose blood levels are around 5mM, or 10mM after meals. In capillaries these levels can rise by about 40 %. I haven't found measurements of glucose concentration in tissues, or in extracellular ...
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11 views

Could there be some safe, hypothetical way of turning on and of thermoregulation?

This is something I thought of with the whole artificial gill concept. Could a modification to the brain/nervous system allow a human to turn off their thermoregulation in air/water of the right ...
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21 views

Anaerobic nutrient expenditure

Doing some research into different forms of exercise and energy systems and I realized something odd about the way we talk about energy. When we eat, we take on macronutrients that are broken down ...
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19 views

Need to solve a “pseudo-metabolic” network for rates

following problem: I have data on a certain complex association network (from monomers 1 ... 8 to complexes of all combinations, such as, 12 ... 13 ... 18 and so on until 12345678, so that I know ...
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10 views

Is it possible to stimulate the EPOC process?

On Wikipedia, EPOC is defined as: Excess post-exercise oxygen consumption (EPOC, informally called afterburn) is a measurably increased rate of oxygen intake following strenuous activity intended ...
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15 views

Bilirubin metabolism pathway in non-human primates (NHP)?

In human UGT1A1 seems to be the only relevant enzyme to glucuronidate unconjugated bilirubin into excreted forms. Is the pathway the same for e.g. the Cynomolgus monkey (Macaca fascicularis) in vivo? ...
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24 views

Why does our body regulate metabolic processes using the thyroid hormone?

People with hypothyroidism do fine when taking medication containing their daily dose of thyroid hormone. This means that the signaling function of the thyroid hormones is, in principle, unnecessary. ...
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23 views

If chylomicrons can not get into the capillaries, how do they supply to tissues?

The transport of chylomicrons is into the lacteals mainly because they are too big to get into the capillaries and yet they later supply triglycerides in the extra hepatic tissue by traversing in the ...
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18 views

Glycoprotein hormones metabolism

Why do the carbohydrate groups in glycoprotein hormones decrease the rate of metabolism? And increase the half-life?
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27 views

Is there a way to quantify in vivo cholesterol transport rates?

I have always had trouble grasping the physiology of lipoprotein cholesterol transport. The "standard" description found in the literature is that liver synthesizes cholesterol which is carried in ...
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21 views

How are muscle fibre size and oxygen consumption related?

Does anyone know of a paper which correlates the muscle fibre size to oxygen consumption in mammals? I am trying to find a correlation between muscle fibre type, size and (absolute and specific) ...
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39 views

What is the actual function of HDLs and CETP?

I know that HDLs collect cholesterol from peripheral tissues and transport it back to the liver using SRB1 - Reverse cholesterol transport and dumping it in bile. So the tissue is producing some extra ...
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34 views

metabolic heat generation and exercise intensity

Is there a relationship between bio heat equation (found here) and exercise intensity as described here That is I am trying to include the effect from exercises to the tempertaure variation in skin. I ...
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57 views

How much energy would it cost to synthesize all cholesterol requirements de novo?

Imagine a scenario in which some person is unable to absorb any dietary cholesterol because of some intestinal mutation (for example). Thus, they have no cholesterol available from their diet for ...
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29 views

Which metazoans host anaerobes to aid in digestion? Do any host oxic digestive tracts?

Many metazoans (e.g., mammals, insects, earthworms) have anoxic digestive tracts that are colonized by anaerobic microbes that perform portions of digestion of food for the host. Some other metazoans ...
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47 views

Which Lactobacillales (Lactic acid bacteria — LAB) strains are capable of degrading starch?

I've been researching bacteria strains but am having trouble finding amylolytic LAB strains with amylolytic and lactic acid producing character. The only species I've found, that are capable of ...
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38 views

Why are carbohydrates the most common short-to-medium-term energy storage form in biology?

According to this table, gasoline has a specific energy noticeably higher than fat and more than twice that of carbohydrates; even short-chain hydrocarbons like ethanol and even methanol offer an ...
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652 views

Why do plants produce so much more sugar than they use?

I recently asked the question, "Do plants need O2 to consume energy they've stored via sugar?" to which @canadianer responded, "Yes, plants require oxygen to generate ATP from sugar. However, they ...
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12 views

How reactive are reduced antioxidant molecules?

When antioxidant molecules stabilize free radicals, they themselves become unstable and reactive but to a lesser degree. How reactive are these reduced antioxidant molecules? And what substance ...
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27 views

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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96 views

Regulation of Cra protein level in E coli

Catabolite Activator/Repressor, Cra protein (formerly known as Fructure Repressor FruR) plays a significant role in central carbon metabolism of E coli. Its activity is inhibited by ...
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205 views

How do cells slowly degrade 5,5'-dibromo-4,4'-dichloro-indigo?

5,5'-dibromo-4,4'-dichloro-indigo is the product of X-gal cleavage, often used as a reporter with B-galactosidase. I've made the (unreferenced) observation that it seems as though the blue product ...
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4 views

term for trophy for a compound when it is not used used by that organism

A prototroph for compound X can make it, a bradytroph grows faster if X is scavenged, an auxotroph needs to scavenge it and a hyperauxotroph lacks both the biosynthetic pathway and the transporters. ...
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19 views

Fate of Acetyl CoA in well fed state?

When we have eaten well and take fat rich diet then in this condition Acetyl CoA produced from fatty acid breakdown will be gone to storage in adipose tissue or not? If it will go for storage then why ...
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12 views

How to Stabilize Histamine Surges in Exercise of MD/DMII?

I am studying how to stabilize histamine surges/effects without antihistamines in exercise of Metabolic Syndrome (MD) and Diabetes Mellitus II (DMII). Generic/simplified case: Symptoms in exercise: ...
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17 views

Bilirubin metabolism and UGT1A1 inhibition in human vs. monkey?

In human UGT1A1 seems to be the only relevant enzyme to glucuronidate unconjugated bilirubin into excreted forms. Is the pathway the same for e.g. the Cynomolgus monkey (Macaca fascicularis) in vivo? ...
0
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0answers
24 views

Diffusion coefficients of glucose in mammal tissues?

Where can I find estimates/experimental measurements of the diffusion coefficient of glucose in mammal tissues? Specefically I mean the inter-cellular space. I'm not looking for a specific tissue, so ...
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30 views

Can an inhibited enzyme be activated by an activator molecule binding to a second allosteric site?

Can the inhibition caused by a inhibitor molecule(ATP that attaches itself to an allosteric site of a subunit of the PFK-1) be reversed by the binding of an activator molecule (AMP that binds to an ...
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31 views

Why is alcohol purged from the body more slowly when we sleep?

It is a popular belief that when you get asleep after drinking alcohol, in the morning you have higher level in your blood than if you stayed awake the whole night. Is this true? If so, why? Is it ...
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17 views

Can a computer display work as a daylight lamp?

During winter time I often see advertisements for daylight lamps which are supposed to compensate for the lack of daylight in a winter season. The specs of such a daylight lap seems to be an LED ...
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27 views

Is there any evidence to suggest that exercise reduces the side effects of caffeine?

I heard a friend say: I'm not drinking coffee this week. My body can only process the caffeine if I run at least 15km a week. I found this claim fascinating - that exercise temporarily ...
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11 views

What's the relationship between Drugbank drugs and SMPDB pathways?

In the 'pathway browse' panel SMPDB pathways and their corresponding Drugbank drugs are listed. What are the relationships between the drugs and the pathways? Some listed drugs are not in the ...