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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 there a difference in body's energy metabolism (glucose/fatty acid/amino acid metabolism) during exercise as compared to fasting? [on hold]

Does the body respond in the same way to regulate metabolism during exercise and fasting? Thanks
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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 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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What is the balance of fundamental inputs and outputs for the human body?

What is the balance of fundamental inputs and outputs for the human body, excepting vitamins and trace minerals? For example, I know that the average adult consumes 0.84 kg of oxygen per day and ...
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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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What is oxygen used for in cancer cells other than respiration?

This question stems from a reflection I had on cancer cells: It is known that cancer cells switching from aerobic respiration to anaerobic metabolism. Hence, they should be able to survive in the ...
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Are there chemicals/materials which when injected in blood stream remains there for long?

Does human body detect all foreign bodies? If a chemical or pathogen or tiny particles(few microns diameter) are injected in blood stream, will they be removed from the body or destroyed sooner or ...
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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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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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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 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 Kreb's cycle pathway to generate more ATP after glycolysis, but most bacteria cannot utilise the Kreb's cycle plant cells can utilise the ...
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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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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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59 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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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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106 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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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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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
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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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1answer
86 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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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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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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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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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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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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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
505 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?
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Why are my calculations for O2 requirements of daily metabolism so far off?

When I attempt to calculate the O2 necessary for a day of metabolism at rest (for an imaginary average human) and compare it with the expected O2 consumed per day my results differ by a factor of 3. I ...
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117 views

Why can't humans use dietary citric or acetic acid as a primary source of energy?

As the Krebs cycle is involved with the conversion of food in to citric acid, why can't eating citric acid be used as a temporary primary source of energy - in place of fat/carbohydrate/protein?? It ...
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156 views

Transaldolase vs Transketolase

What is the difference between transaldolase and transketolase in the pentose phosphate pathway? From what i understand, they both catalyze the transfer of carbon chains from 1 aldose into 1 ketose to ...
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1answer
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why is LPL (lipoprotein-lipase) down-regulated during fasting?

During fasting our body needs additional sources of energy and that's why triglycerides are broken down into fatty acids and glycerol. where fatty acids can be used to generate acetyl-coA and ...
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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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Is there any evidence that supports glycolysis in mitochondria or chloroplasts?

Glycolysis is known to be a part of cellular metabolism undergone by both eukaryotic and prokaryotic cells, whether under aerobic or anaerobic conditions. As the endosymbiotic theory states that ...
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How short chain fatty acids directly enter blood vessels?

Long chain fatty acids enter lymph and then get drained into blood vessels. But why short chain fatty acids don't go this pathway? Is it related with solubility?
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Is there a point in our life when ALL the atoms from our childhood's body get replaced?

The evolutionary biologist and Oxford professor Richard Dawkins makes on his TED talk the rather interesting suggestion that we human beings, are in nature more similar to a wave than an object. In ...