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Questions tagged [metabolism]

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

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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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Is there an endothermic reaction with glucose without needing to be activated? [on hold]

Is there an endothermic reaction with D-glucose as substrate that does not require the glucose to be activated?
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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 uA (e.g. 1, 2), thereby using roughly 3E-06 Watts, and that converts to roundly 2.6E-...
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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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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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1answer
36 views

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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1answer
22 views

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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56 views

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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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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1answer
60 views

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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1answer
89 views

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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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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84 views

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 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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Complete metabolic map of humans [closed]

Do we have the complete metabolic map for humans? Do we know from the genome what enzimes are expressed and what each enzime does?
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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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How cells determine how many enzymes are needed for digestion

How do pancreatic cells, epithelial cells of the stomach and intestinal epithelium cells determine the right amount of enzymes for digesting carbohydrates, proteins, fats? How does the pancreas ...
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2answers
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Why is Cacao a stimulant?

As I write this I've just eaten a fair amount of cacao (not cocoa) powder and it's given me quite a buzz. I've googled the effects and the Internet seems to think it's somehow psychoactive although it'...
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219 views

How does a glucose molecule enter the cell from blood vessel?

The transporters in the plasma membrane of the cells promote the entry of glucose molecules from the extracellular matrix to the cytosol of the cell. Could someone explain how does the nutrient ...
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1answer
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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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1answer
71 views

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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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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Can the face bones be “compressed” or forced together? What would happen? [closed]

Say someone doesn't like that their maxilla bone is too long because the height of the maxilla affects the placement, position and angle of the mandible relatively. If one were to apply mechanical ...
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1answer
32 views

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 is the actual charge of NAD at physiological pH (roughly 7)?

I am curating a metabolic model using CobraPY. Mass imbalances often occur in equations. Many different websites e.g. Kegg, ModelSEED, PUBCHEM, etc. have differing charges and formulas for compounds. ...
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What waste products do cells secrete in culture, and at what rate?

I am designing microfluidic chips for mammalian cell culture. One aspect I am interested in modeling is the rate at which I must renew media to ensure that: Cells receive enough nutrients Cytotoxic ...
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What determines the energy efficiency of our bodies?

Ingested food is broken down into the macronutrient components and then absorbed into the body. They are then used immediately or stored for future use. However, our energy efficiency is very low. So, ...
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1answer
62 views

Can something like McDonalds be considered a life form?

"The current definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to ...
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2answers
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If life began at sea, why organisms are less salty than the sea?

We may take it for granted that a fish, a seaweed, or clams are not too salty to eat, although the sea around them is salty. I know about the existence of a mechanism which prevents their body from ...
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212 views

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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1answer
283 views

Does Povidone-Iodine that penetrates through the skin stays in the body (cells, liver etc)?

Here it says on povidone-iodine: "Route of Elimination: Povidone-Iodine is intended for topical application and is not eliminated" "Clearance: Povidone-Iodine is intended for topical ...
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1answer
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Specific Neurons that Require Glucose

I've been doing a bit of armchair biology lately, and have been interested in the metabolic flexibility of neurons. My understanding is that, besides glucose, many neurons can metabolize lactic acid ...
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Why is hydrogen sulphide being generated on Caribbean beaches?

Once again, there has been a massive influx of Sargassum weed in the Caribbean. It is coming ashore on Atlantic facing beaches and forming piles up to 3m deep. As it dries and decays, hydrogen ...
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Higher Dissolved Oxygen Content

I conducted a project where the metabolic rates of Hermit Crabs were to be measured in reaction to changing pH. I used SeaChem Acid Buffer to lower pH - it converts carbonate alkalinity (CO3 2-) to ...
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1answer
138 views

How is the urea cycle regulated with respect to protein deficit?

Proteins cannot be stored in the body. Excess proteins from the diet are deaminated in the urea cycle that takes place in the liver. The liver is the first contact since these amino acids are ...
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137 views

Can E. coli make pyruvate from acetate?

What pathway would E. coli use to make pyruvate from acetate? I have found several papers that refer to a possible mechanism that could move acetate to pyruvate via a three-step process: Step 1: ...
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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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1answer
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When you lose weight, how does the mass exit your body?

As a thought experiment, consider the case of Angus Barbiery, who allegedly lost almost 200kg in about a year by not eating at all, save for necessary nutrients provided as supplements. My question ...
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470 views

Why does GLUT2 (With a high Km), bind less glucose at a lower glucose concentration (below Km)?

A text I am reading says "GLUT2 is a low-affinity transporter in hepatocytes and pancreatic cells. After a meal, blood travels through the hepatic portal vein and GLUT 2 captures excess glucose for ...
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Dangers of excess blood protein? [closed]

Like glucose, amino acids are also insulinogenic as well. So, presumably, just like glucose, the body would also like to keep amino acids levels in the blood stream below (or within) some certain ...
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1answer
24 views

Are some polyketides enzymes?

I am currently reading a "book" (rather an article) called "Protein Modelling & Molecular Docking: Modeller, Autodock". The abstract starts with the following sentence : Polyketides are a ...
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1answer
64 views

Cause of Obesity

Considering the normal function of adipose tissue in sequestering 'persistent organic pollutants [POPs]', is there any evidence that the existence of such POPs within fat cells interferes with the ...
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2answers
258 views

Was lactose present in the environment before the evolution of mammals?

Are there lactose sources other than dairy products in nature? I tried to search for it but I did not find anything. The question arose because I was wondering whether lactose-utilising enzymes in ...
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Bacteria utilize short chain fatty acid as energy source

I'm doing research about the short chain fatty acid producing bacteria. I studied 7 short chain fatty acid (acetic propionic butyric isobutyric valeric isovaleric and captionic). and I found that the ...
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What happens to lipoprotein lipase after a sugar only diet?

Insulin increases the activity of lipoprotein lipase thay allows cells to take in lipids from chylomicrons in the blood. If a person takes a sugar only meal like drinking coke, insulin is released. ...
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1answer
203 views

Does thyroxine increase BMR or metabolic rate?

I know that thyroxine increases the metabolic rate, but my teacher said it increases the metabolic rate, not the basal metabolic rate, the basal metabolic rate is always the same. What's the ...
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1answer
748 views

ATP Hydrolysis to AMP in the Urea Cycle. What is the Free Energy Change?

How is the hydrolysis of ATP into AMP and PPi in making arginosuccinate equivalent to the hydrolysis of 2 ATP?