Questions tagged [metabolism]

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

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How important is getting enough glucose for maximal brain performance / cognition?

I know from many studies that have been done, that resting versus active use of the brain has relatively similar overall energy expenditure levels. On the other hand, however, we know that the brain ...
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Is the lac operon repressed in the presence of both glucose and lactose?

In the presence of both sugars (glucose and lactose) will there be repression of the lac operon completely? I know that more glucose means less cAMP --> less CAP --> less positive regulation, and ...
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Is cellular biomass synthesis and reactive oxygen species generation coupled with each other in cells?

Assuming that total ROS = ROS generated during biomass synthesis + ROS generated for other metabolic tasks, is it possible to quantify the amount of ROS generated specifically during biomass synthesis?...
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Can radiation exposure cause cancer later in life even if no traces of radioactive material are present in the body anymore?

I had a long-lasting debate with a friend of mine about the Fukushima incident. The question that we tried to solve was if radiation or toxin exposure can cause cancer later in life even if no ...
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How would a medication cause a one to maintain a different weight?

This isn’t really a medical question, I’m just really curious about this. I was maintaining weight A and then started taking a medication that brought me to weight B. While on the medication, I ...
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What triggers the switch between aerobic and anaerobic respiration?

I understand that when there is a shortage of oxygen cells convert the pyruvic acid from glycolysis to lactic acid to regenerate NAD+. What I don’t understand is how they switch to anaerobic ...
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How does anaerobic bacteria produce ATP for it's own cellular activities?

Anaerobic bacteria utilise glycolysis: Glucose + 2 P + 2 NAD+ => 2 ATP + 2 H + 2 NADH + 2 H2O + 2 Pyruvate followed by fermentation: Pyruvate + NADH => Lactate + NAD+ The resultant NAD+ formed ...
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Could certain drugs enable one to consistently eat above TDEE or BMR without fat gains?

I heard anabolic steroids and stuff like DNP and ephedrine and etc. can somewhat enable one to eat more and get away with it without much or any fat gain, despite eating more than the body would ...
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Is it possible to stop more/extra fat from being stored in the body?

I don't mean simply by restricting eating or upping the activities, but a way to basically stop the body from adding more fat on itself down on the bio level. For example, I'm not too knowledgeable on ...
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Is lemon water an alkalizing agent in the body?

I was recently having a discussion with someone about whether lemon water actually increases the pH of your body (by which I assume they mean the blood); their claim was that once Citric acid was ...
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What is the difference between Warburg effect and Crabtree effect in metabolism? [closed]

In addition to answering my question, please suggest a good review article that provides comparison of the above effects. Which pathways affect central carbon metabolism to produce these effects? Also,...
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What is the net effect of pancreatic somatostatin and how is it regulated?

I've read the following facts about pancreatic somatostatin released from delta cells of the islets of Langerhans: Blood glucose, fatty acids, and plasma amino acids stimulate somatostatin ...
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How much energy do small spiders expend when they are just waiting for their web to vibrate?

Roughly speaking, a small, complex electronic circuit or IC might sit in "sleep mode" using a current of roughly 1 µA (e.g. 1, 2), thereby using roughly $3\times 10^{-6}$ Watts, and that ...
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Why is urea not converted to ammonia in the body?

After the liver processes metabolites to produce urea and other by-products, these travel in the blood to the heart, then they are oxygenated, and some travel through the renal artery to the kidneys. ...
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What are the differences between carnitine forms?

I've heard of L-carnitine, acetyl L-carnitine and L-carnitine L-tartrate. What form(s) occur in meat? What form does the human body manufacture? Is L-carnitine just a shortened name for L-carnitine L-...
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Is there a relationship between HDL-C and LDL-C?

For a gentle introduction to cholesterol and its functions, see a great answer on SE Biology Whenever I read about how to deal with cholesterol level, the rule is to keep a low LDL fraction, ad a ...
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Is homocysteine converted to glutathione during oxidative stress?

From the paper titled "The basis for folinic acid treatment in neuro-psychiatric disorders" by Ramaekers et al., 2016: On the left side of the figure, the purine metabolite GTP serves as the ...
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Where does an organism store reserves of amino acids?

Where does an organism store reserves of the amino acids it needs to build various proteins it needs: in the liver? in the blood? in every cell?
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Term of the type xxx-troph for a compound not used by an organism

A prototroph for compound X can make it A bradytroph grows faster if X is scavenged An auxotroph needs to scavenge X A hyperauxotroph lacks both the biosynthetic pathway and the transporters for X ...
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What determines the metabolic pathways that a biological cell is able to carry?

For example: human cells (eukaryotes) can utilize the Krebs cycle pathway to generate more ATP after glycolysis, but most bacteria cannot utilise the Krebs cycle plant cells can utilise the Calvin'...
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Why isn't acetyl-coA an entry point for gluconeogenesis?

The process of gluconeogenesis starts from various possible precursors - plausible entry points like, Pyruvate, OAA, Fumarate, Propionate (as succinate) and alpha-KG. It is important to note that, ...
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Do birds emit infra-red radiation?

I'm an electronics engineering student and I am going to use a sensor that detects infra-red emitted by birds that invade rice paddies. Do birds emit infra-red radiation?
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What is the source of the electrons generated in the Krebs cycle?

In the Krebs cycle, where do the hydrogens and electrons that NAD+ and FAD accept come from? It seems that citric acid only loses two hydrogens because it starts out with eight hydrogens and then ...
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How much solar energy required to produce enough food for a herbivore?

Just curious, how much solar energy can power an (herbivore) animal? Specifically, is it enough sunlight on Mercury (4 to 10 times brighter than on Earth) to "feed" a zebra? Will it be sufficient at ...
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Why do mice have a higher metabolic rate than humans?

Mice and other small animals have higher metabolic rate than humans. How does that happen on cellular level, if we look on one cell in the mouse body? What is it in this cell that will be different?...
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What preceded ATP synthase?

ATP Synthase is ubiquitous throughout life on earth and so most probably evolved within the last universal common ancestor (LUCA) before that lineage diversified into the various kingdoms of life. ...
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How is Saccharomyces cerevisiae grown on acetate and ammonium able to produce TCA intermediates?

I am working with a metabolic model of Saccharomyces cerevisiae and I am studying its growth on acetate and ammonia. I am performing Flux Balance Analysis to compute the growth rate and then I am ...
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How can I obtain a computer readable model of Dr. Gerhard Michal's biological pathways map?

I want to run simulations of various metabolic pathways – the project could end up becoming quite large, and having a machine readable chart would make thing a lot easier. Does anyone know if there is ...
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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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What is the genetic background for fast metabolism?

I am wondering if it is possible that people with very fast metabolism have some genetic mutation. There are people who can eat a lot while others would definitely get fat with such a diet. In other ...
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Is lysergic acid diethylamide (LSD) metabolized in the body?

Is LSD broken down into other compounds by enzymes or hormones? If so, at what point and where in the body does this happen? I researched several papers appearing in a google search, but unfortunately ...
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What does differential consumption mean? [closed]

I have not been able to find any definition of differential consumption online. What does it mean in this quotation? Vertebrates can influence natural fire regimes in several ways. First, ...
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What's the relationship between oxygen consumption and ambient oxygen concentration for a lobster?

I was looking at a research paper by Thomas (1954) and came across a graph with ambient oxygen concentration plotted against oxygen consumption rate of a European lobster kept in water. As we can see,...
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Inhibition of beta-oxidation by acetyl- or malonyl-CoA

Which molecule, in excess, inhibits beta-oxidation? a. Acetyl-CoA b. Malonyl-CoA The answer to this question seems debatable to me, as I think both are correct. However, according to my ...
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What's the lowest temperature a tardigrade can remain active at?

There's a lot of information floating around the net about how tough they are & what they can survive, like "We now know that some tardigrades can tolerate being frozen to -272.8 °C". But any ...
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What's the lowest atmospheric pressure a tardigrade can remain active in?

I'm not asking what atmospheric pressures they can survive (we now they can survive the vacuum of space) I'm wondering at what point a deficit of atmospheric pressure would cause them to enter one of ...
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Is there a name for the use of sunlight in metabolic processes?

"Photosynthesis" is what is used to describe how plants use sunlight to synthesize sugars, but, I also heard some animals like humans use sunlight in the process of creating vitamin D. Is there a ...
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Why would lactate be high in diabetics?

Why are lactate level high in diabetes? For example, type II diabetes are resistant to insulin. If those patients are insulin resistant their gluconeogenesis should be working at a high rate and, ...
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Plotting metabolic networks?

I need to draw a map of the core metabolism of E.coli. Associated with each reaction in the map I have a number that indicates the flux through this reaction. I want the map to reflect these fluxes ...
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What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...
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Since frogs are ectotherms and supposed to have low metabolic rate, why do they grow so fast and eat so much?

It's always emphasized in literature that endothermy enables high growth rates but requires more food. But look at frogs, for example: bullfrogs, toads, pacman frogs etc. They would readily eat a ...
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When consuming carbohydrates and fats together, why are the fats caloric?

If I understand things, and I most likely don't: mammals primarily use carbohydrates to produce metabolic energy when there are sufficient carbohydrates to do so. The use of fats for fuel requires ...
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Where is ethanol detoxified? peroxisomes or smooth ER? Or both?

I am reading the textbook Biology (Campbell et al, 2005), and I am confused. In Chapter 6.4, on page 104, it says that "In the smooth ER, other enzymes help detoxify drugs <...>", and alcohol is ...
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Why our body does not produce polyunsaturated fatty acids?

Our body does not produce two polyunsaturated fatty acids (PUFA): linoleic acid and alfa-linolenic acid. I am thinking reasons for it. Saturated fatty acids have more energy than unsaturated. ...
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Why does pyruvate from lactate and pyruvate from other sources follow different pathways in gluconeogenesis?

My teacher taught me in a lecture that PEP forms from Pyruvate by two ways, based on their sources, that is - 1. If the Pyruvate was from lactate (by lactate dehydrogenase action), it gets shuttled ...
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Is gut bacteria Succinivibrionaceae's low methanogenesis understood well enough for GM of cattle gut bacteria to be considered?

After watching the Periodic Table of Videos episode linked in this question I watched the episode Wallabies and Methane where Sir Poliakoff says (a bit after 02:00):...
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Why is some scat in the form of little pellets?

The scat I most often encounter when out and about is from coyotes, black bears, deers and rodents. The deer and rodent droppings I find are in little pellets, what is different about their digestive ...
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How are Mono and Diglycerides metabolized without the Free Fatty Acids of Triglycerides?

Having difficulty figuring out what the body does with ingested mono and diglycerides if the usual process of TAG metabolism includes the FFA released from the TAG returning to the MAG to recreate a ...
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During starvation, does the human body do anything to prioritize which organs receive nutrients?

When food is scarce, the body slows its metabolic rate to conserve energy. Are there any other systems or processes that prioritize which organs receive nutrients?