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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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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1answer
80 views

What is the effect of exendin on beta-cells?

Do you know if exendin, an analog of GLP-1 (glucagon like peptide-1), can be toxic for beta-cells? For example, what is the effect on INS1 or Min6 cells at a certain concentration or after 90 mins of ...
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2answers
89 views

Conversion and storage of glucose to glycogen

Why is excess glucose, synthesized to glycogen, stored only in limited amounts, as compared with lipids/triglycerides that are stored in our body? Why is mature glycogen arranged (polymerized) in 12 ...
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4answers
2k views

Why do obese people tire quickly?

Fat people have a large amount of calories (energy) stored, but I have noticed all time when they do physical activities they get tired fast in comparison to fit people - why does this happen?
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2answers
236 views

Relationship between our microbiome and personalized nutrition

Recently, it has been asked whether there are 'metabolic types' between humans that can benefit from a sort of personalized nutrition. One answer suggested that one discerning factor could be the ...
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2answers
108 views

Energy metabolism in Cancer cells

The TCA cycle intermediate Isocitrate dehydrogenase commonly undergoes point mutations in cancers. This allows IDH to reduce a-Ketogluterate to 2Hydoxygluterate, causing a reduction in pVHLs ability ...
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1answer
135 views

If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
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0answers
41 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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1answer
119 views

How does the pancreatic beta-cell know how much insulin to secrete in response to glucose?

How do $\ce\beta$-cells know how much glucose is in the blood? I know that when glucose enters a beta cell it triggers the cell to produce insulin. $\ce\beta$-cells trap glucose by converting it into ...
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2answers
95 views

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-...
2
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1answer
383 views

Why do mice have a higher metabolism?

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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0answers
19 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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2answers
43 views

Is there a known or quantifiable correlation between capsaicin and its effect on the body's metabolism?

I've often heard that spicy foods can speed up your metabolism, I presume, due to the capsaicin. Though I'm sure this is a minor effect - I doubt eating a pound of jalapenos a day will help me lose ...
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2answers
434 views

Can a living organism run on electricity?

Each time I'm too lazy too cook I think it'd be cool to be able to just plug myselt into an outlet. Yet I know it is not possible - I need amino acids and a lot of other stuff that electricity can't ...
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0answers
39 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 ...
2
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1answer
72 views

Are there differences in energy of glucose isomers?

There are many isomers of glucose, including galactose and fructose. Do they have different chemical energy levels, and why? What makes galactose and fructose useful compared to glucose, and would ...
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2answers
654 views

When glucose production is low, the brain begins using ketoacids as energy… how does that work?

Can someone very generally describe how the brain consumes ketoacids/ketone bodies when blood glucose has been completely depleted?
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1answer
179 views

ATP utilized in Glycolysis vs. Gluconeogenesis

In glycolysis, the conversion of glucose to pyruvate results in a net gain of 2 ATP molecules. In gluconeogenesis however, the conversion of pyruvate back to glucose requires 6 ATP molecules. Why ...
3
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1answer
50 views

Why would growth hormone (somatotropin) cause both lipid AND glucose release?

GH increases lipolysis (lipid breakdown) and the release of fatty acids from adipocytes into the blood. Fatty acids then can be used as energy sources to drive chemical reactions, including ...
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0answers
71 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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1answer
9k views

What are the differences between white and brown adipose tissue?

What are the differences between white and brown adipose tissue? Here are some that I have come across: ...
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0answers
121 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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0answers
72 views

Giving life to a dead person [closed]

Could anyone please tell me whether we can conclude that no body of a dead human being can get life since all chemical reactions are irreversible in our human body?
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0answers
30 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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1answer
26 views

Does the location of the double bond in chlorins yield a distinct biological function?

Chlorins differ by the number of double bonds and their location. Chlorin has 20 pi electrons, whereas bacteriochlorin and isobacterichlorin have 18 pi electrons, but at different locations. Do ...
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0answers
30 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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1answer
39 views

ATP yield of fermentation: study to cite?

Everywhere I find the ATP yields of respiratory and fermentative metabolism of glycolysis. While that of oxidative phosphorilation I could find in Stryer to cite one study where this was addressed (...
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3answers
213 views

Why is iodine used for metabolic hormones?

Iodine and related biological iodine-carrying hormones are phylogenetically very old, at least according to Wikipedia. Humans use iodine as a metabolic indicator, as do axolotls and apparently most ...
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1answer
69 views

Metabolic efficiency for fats and sugars

I am making an exercise for physics students about the first law of thermodynamics, burning heat and evaporation heat. So my idea is to use cycler which runs on fats and sugars where proportion ...
2
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1answer
116 views

what makes our body warm?

I would think that there would so many chemical reactions going inside our body,friction produced by blood in veins, subcutaneous and visceral fat acting as heat insulators. I was wondering to what ...
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0answers
49 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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1answer
618 views

Why are many fruits sour?

Many fruits (like apples, berries, citrus fruits etc.) contain high levels of organic acids, especially malic acid and citric acid. Are there any evolutionary functions of those acids in ripe fruits? ...
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1answer
75 views

What are the metabolic concerns associated with hard water?

If humans can maintain a consistent blood pH, then what problems does alkalized water cause us? Why is it recommended that we filter and boil hard water? Is the issue that hard water can affect the ...
4
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1answer
661 views

How was the diversity between ethanol fermentation and lactic acid fermentation evolved?

Quite simply, some organisms metabolize glucose under anaerobic conditions via Glucose->(2) Pyruvic Acid->(2)Ethyl Alcohol. Some organisms, however, metabolize to lactic acid. When did such a process ...
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1answer
103 views

What happens when we eat excess fat?

The fats in our body are stored in fat cells. When we over eat fats does the size of our fat cells increase, are more fat cells generated, or do we "throw out" excess fat?
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1answer
998 views

Grapefruits and CYP3A4

Grapefruit juice contains furanocoumarins, which irreversibly inhibit CYP3A4. For this reason, when one is taking certain medications it is necessary to not eat grapefruits because the inhibition of ...
3
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2answers
342 views

Equilibrium and Metabolism: Can cells exist at STATIC equilibrium? What about dynamic equilibrium?

I understand that in closed systems, once reactions reach equilibrium, they can no longer be used to power other reactions. If a cell was a closed system (which it is not), being at equilibrium would ...
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2answers
646 views

Should we induce fever to assist healing?

I am currently reading "The Fundamentals of Anatomy Physiology" 10th edition, and have found it an incredibly interesting book. I have just been reading about the lymphatic system, and the various ...
5
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2answers
237 views

Energy released during the production of ATP?

When glucose is used during aerobic and anaerobic exercise, how much energy is expended or required? During aerobic exercise: $C_6H_{12}O_6 + 6 O_2 \to ATP + H_2O + 6 CO_2$ + energy During ...
3
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1answer
108 views

Catabolism and muscle energy intake

From my own reading, there are three ways used by the body to produce energy: Alactic anaerobic (direct degradation of ATP and creatine phosphate for regeneration of ATP) Lactic anaerobic (breakdown ...
6
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1answer
252 views

iodine: how did they manage without it in old ages? (People who were living far from the sea)

Knowing that today iodine comes either from fish products or (artificially) enriched table salt, how did people who lived far from the sea survive before (especially during the the Middle Ages)? Edit ...
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1answer
49 views

What does “each pathway define an independent genotype” mean?

In a section of this paper. However, if the question of independency is posed in the form: “Does each pathway shown define an independent genotype?,” then each of these three pathways is ...
2
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1answer
77 views

What is the meaning and significance of extreme pathways

Can someone please explain me what extreme pathways are? I found this definition in this article: Extreme pathways are a unique and minimal set of vectors that completely characterize the ...
3
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2answers
9k views

What causes muscles to generate heat on contraction?

I'm curious what the exact cause is of dramatic heat generation that comes along with muscle activity. Can anybody explain this in understandable language?
5
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2answers
155 views

Burning fat transferred from one part of the body to another

While doing some research on cosmetic surgery, I discovered that there are several ways of doing breast enhancements, one of which was using body fat. While I haven't researched this method, I assume ...
2
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1answer
41 views

MTHFR recessive alleles and B-vitamins

I know that being heterozygous or homozygous recessive for the MTHFR gene prevents that person from being able to process and use folate and B-12. It causes an unhealthy level of homocysteine to ...
10
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3answers
29k views

Why can't the brain and red blood cells use fuels other than glucose?

The question is rather straight forward: I have always been curious as to why, but cannot find an explanation online. I can imagine that the mechanism is different for each, but why does brain tissue ...
3
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1answer
113 views

Can cats use ketone bodies as only source of energy?

I recall reading that much of the energy a cat produces from its food comes from proteins which I assume would produce energy via being catabolised into amino acids which in turn, if glucogenic, would ...
4
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1answer
104 views

Do mitochondria use ATP in order make another ATP from glucose?

Do mitochondria use ATP in order make another ATP from glucose, or does it use another source of energy to convert glucose to ATP?
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2answers
325 views

Breakdown of energy expenditure at the level of a single cell

The metabolic rate measures how much energy an organism expends over a unit of time. Its breakdown for the human body in terms of its functions is well documented : so much for the heart, for the ...