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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Co-dependency between carbohydrates, fats and protein in the mammalian diet?

Following up from the question Are carbohydrates an essential component of human diet? I am interested in knowing more specifically how carbohydrates, fats and proteins are linked in the mammalian ...
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2answers
42 views

How did scientists establish the reactions that occur in metabolism? [on hold]

How did scientists establish that macromolecules like proteins, carbohydrates and lipids are synthesized from other molecules with intermediate products by living cells. Did they observe this under ...
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1answer
47 views

Is there a certain environment where all cellular functions (or at least some) increase their rate?

Is there a certain environment in which all the functions (or some) inside a cell increase in their rate? Would the increased rate cause any damage to the cell?
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1answer
30 views

Are there known functions of AST, ALT, and amylase in the blood?

A number of enzymes can be measured in the blood or plasma that aid in the diagnosis of certain diseases. For example, patients with particular liver diseases may have elevated aspartate ...
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1answer
63 views

Why is the Pentose Phosphate Pathway so active in erythrocytes?

Is it because glyceraldehyde -3-phosphate (a molecule which when enter glycolysis help produce ATP through substrate level phosphorylation) can be prepared without losing an ATP through this process?
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3answers
103 views

What is the actual storage form of energy in muscles? ATP or Glycogen?

I was asked this question in my latest exam. I think the answer is Glycogen because ATP doesn't store energy for a long time so it isn't the ACTUAL storage of energy. Some classmates argue that in ...
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2answers
35 views

Energy coupling between two spontaneous reactions?

This diagram describes energy coupling between a nonspontaneous reaction (the formation of glutamine from glutamic acid and ammonia) and a spontaneous reaction (the hydrolysis of ATP). I can see that ...
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2answers
56 views

Where do transamination and deamination take place?

The only information I know is about deamination is that it occurs in the liver and kidney. But in which part of the cell does deamination occur? To which tissues is transamination specific, and in ...
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29 views

Can the respiratory quotient be calculated from a formula or must it be measured directly?

I found the following question on the Respiratory quotient: A normal human diet has a Respiratory quotient (RQ) of approximately 0.85. Given that pure oxidation of fatty acids has a Respiratory ...
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26 views

Validity of measurements of respiration in isolated mitochondria

I've recently read a couple of papers on exercise and mitochondria, in which state 4 and state 3 respiration rates and ROS production are assessed in vitro after exercise has been performed (i.e., rat ...
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1answer
25 views

Do I have to chew for digestion to kick in?

Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"?
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2answers
47 views

Where do plants obtain the metal ions needed for biological processes?

Enzymes employ metal ions (e.g. Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn) for catalysing certain reactions. Let's consider planting a seed. Where will it obtain these metal ions from? Just from water?
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23 views

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 it and a hyperauxotroph lacks both the biosynthetic pathway and the transporters. ...
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24 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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1answer
38 views

Why are both glucagon and cortisol released in hypoglycemia?

Cortisol is released in response to prolonged stresses; one situation when cortisol is released is when blood glucose level is low. In this situation cortisol acts on adipose tissue promoting fatty ...
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31 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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1answer
58 views

What is the substrate for glycogenesis?

In glycogenesis (i.e. the synthesis of glycogen), are sugar phosphates the direct substrates for glycogen polymerization? I would certainly think so since glucose is phosphorylated and then stuck onto ...
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1answer
32 views

Thyroid hormone metabolism and excretion

My understanding is that hormones generated by the thyroid gland, including, for example, T4, are excreted and recirculated in the body through the digestive tract. The reason for thinking this is ...
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1answer
55 views

Why does cold kill humans but not bacteria? [closed]

Bacteria can continue like nothing happened after being exposed to low temperatures why doesn't this happen to humans as well? Why can't our metabolic machinery continue as normal?
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15 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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1answer
43 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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14 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 ...
2
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1answer
36 views

Can lactate be created in ketosis?

After looking at Cori Cycle (from wikipedia) I have a question about how the lactate can be produced in ketosis. According to this article: in a low-glucose state, where the body senses that ...
2
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1answer
48 views

Does the body prioritise the use of available sugar before fat?

Let's say you eat a very unhealthy snack that contains 90% sugar and 10% fat. Would somatic cells not start using the fat for energy until all the sugar is used up? Does the body not use fat at all ...
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25 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? ...
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1answer
57 views

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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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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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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1answer
70 views

How are ions 'pumped' across a membrane during electron transport?

A number of sites (including this one) that provide descriptions of photosynthesis state that high energy electrons 'pump' ions across a membrane. What is the actual 'pumping' mechanism? I've looked ...
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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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26 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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1answer
119 views

What is ATP and why is it said to be a source of energy? [closed]

Is ATP a molecule or a kind of energy. When I studied the active transport, it's said the ATP would release energy to change the carrier protein shape. So confused. Thanks for your help.
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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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16 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? ...
3
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1answer
32 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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1answer
57 views

What are calories and how to burn them? [closed]

What exactly is a calorie? When burning calories, do we always lose fat? I have tried many apps to measure calories, do they give exact amounts? How many calories should be taken a day?
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27 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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1answer
50 views

Why does protein kinase C activated by different means have different effects?

I could be way off base but I think I remember learning that Protein Kinase C has some effects when activated by one pathway and other effects when activated by another. How does this happen? Is it ...
2
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1answer
44 views

How many calories do gut bacteria burn?

It has become well-accepted that microbiota of the gut (a.k.a. gut bacteria) consume calories that are ingested and can have significant effects on energy metabolism in humans. For example, if you ...
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2answers
79 views

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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0answers
29 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 ...
2
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0answers
33 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 ...
2
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0answers
30 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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1answer
53 views

How can space-time affect ageing? [closed]

I recently watched the movie -"interstellar" and I came through the question that how can ageing be affected by space-time? Wherever I look, I get it as a fact that it's kind of ageing slows down in ...
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0answers
20 views

What is the site on an enzyme that binds either exitatory or inhibitory molecules? [closed]

A site on an enzyme where either exitatory or inhibitory molecules can bind is called a(n): A) electron transport site B) active site C) coenzyme D) metabolic pathway E) allosteric site If you ...
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0answers
39 views

Are cold-blooded animals more energy efficient than warm-blooded animals? [duplicate]

When cold-blooded animals extract energy from glucose, do they do so in a more efficient manner than warm-blooded animals? If they aren't producing heat as a by-product, that would suggest that they'...
2
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0answers
33 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 R....
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19 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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3answers
547 views

What happens if a non-diabetic receives an injection of insulin?

If a person without diabetes or any diabetes-related issues receives an injection of insulin, what happens? Would the blood glucose level drop or does the body naturally compensate for the added ...
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1answer
25 views

Where does the lactate produced by tumors go?

Tumors are known to burn glucose and secrete lactate (this is known as the Warburg effect). Where does this lactate go? Does it steadily accumulate in the neighborhood of the tumor? This doesn't ...