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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74 views

Do muscles still hold glycogen reserves if there is no carbohydrate input

Afaik skeletal muscles take glucose from the blood to store it localy as glycogen, to be used in the case of intensive exercise. Does this still happen if the calorie input is exclusively made up ...
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1answer
744 views

Why is the brain dependent on glucose?

The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood ...
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1answer
75 views

Does creatine-phosphate (CP) supplementation regenerate NADH?

I have the following facts: It is possible to convert ATP <-> creatine vice-versa. (ref - non scientific) CP supplementation protects against metabolic syndrome. ref1 ref2 Fructose digestion ...
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0answers
90 views

Does ale give less of a hangover than a lager?

I got into an argument surrounding beer type and hangover. Apparently there is a opinion that ales give you less hangover than lagers do (considering same alcohol content consumed). My understanding ...
2
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1answer
54 views

How are ketone bodies used?

While searching for literature on ketone bodies, I can only seem to find how they are synthesized, but not how they are broken down. I'm looking for the series of events with enzyme names and ...
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1answer
91 views

Why use creatine phosphate?

We use creatine phosphate as an energy storage to resupply ADP with a phosphate group as our muscle cells only contain about 2-5 mM ATP. But why doesn't the muscle cells just keep 20-30 mM ATP instead ...
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51 views

Why doesn't the body optimize how many fatty acids it burns?

Ketone bodies are produced due to an excess of fatty acids being burned (accumulation of acetyl-CoA) so my question is: Why doesn't the body simply regulate how many fats it burns so it doesn't have ...
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41 views

Cholesterol's role in lipid uptake [closed]

I'm studying the digestion of fats and I understand that our dietary fats mostly consist of triglycerides. We absorb the fats and eventually they end up in a muscle/adipose cell for storage (as ...
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1answer
776 views

How can haired mammals synthesize vitamin D?

The human body can synthesize vitamin D in the skin from cholesterol, when sun exposure is adequate. But how can haired mammals do it? Do not they need it?
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1answer
445 views

How is excretion of metabolic wastes from a cell related to its size?

As with anything that is taking place within a cell, the metabolic waste too must be proportional to the size of the cell. In particular the surface area to volume ratio. But how is the waste ...
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3answers
4k views

Is there any use of CO₂ in human body?

We all know CO₂ as a waste product of metabolism . Does CO₂ have any helpful role , apart from having a role in pH of blood ?
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1answer
311 views

What do trans-fats do when in human body?

Trans fats cause health problems, especially to the heart. https://en.wikipedia.org/wiki/Trans_fat#Health_risks My guess is that all effects happen because trans-fats are inherently toxic as the ...
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1answer
45 views

Mitochondria variability per tissue in humans?

I would like to know the distribution of mitochondrial content per tissue type in humans. I understand the simple metric that energetically active or energy requiring tissues will have more ...
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3answers
136 views

What is the relationship between protein-protein interaction networks and metabolic networks? [closed]

I am trying to find out how these networks can be linked together. I know that Protein-protein interaction networks and metabolic networks both fall under the Intra-cellular type of biological ...
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2answers
85 views

How does it make thermodynamic sense for photosynthesizers to turn CO₂ into O₂?

My understanding is that animal metabolism consists of exothermic reactions like $$\ce{C6H12O6 + 6 O2 ->6 CO2 + 6 H2O + energy}$$ This makes thermodynamic sense to me. Animals need an exothermic ...
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0answers
456 views

Why do plants produce so much more sugar than they use?

I recently asked the question, "Do plants need O2 to consume energy they've stored via sugar?" to which @canadianer responded, "Yes, plants require oxygen to generate ATP from sugar. However, they ...
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1answer
34 views

Do plants need O₂ to consume energy they've stored via sugar?

This question came up as I work my way through the answers to another question I just asked. My understanding is that plant photosynthesis looks something like this (though with lots more going on ...
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2answers
508 views

Why are there so many medicinal plants?

Here is wikipedia page containing a list of plants used in herbal medicine. One might first want to argue that many of them actually do not have any medicinal/beneficial effect on heatlth. I think we ...
2
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1answer
55 views

Metabolism of different saccharides

Learning about carbohydrates, I wonder what the differences there are in terms of metabolism, and overall health between the different types of saccharides. In other words, does the body use ...
4
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1answer
40 views

How to measure heat loss in Tardigrades

I want to measure metabolism in tardigrades (a jar of 30 tardigrades). I know that an easy way to measure metabolism is heat loss; I can just measure the temperature of the water before and after a ...
2
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0answers
21 views

Which biosynthetic pathways take place in the plastid and were are they located?

I know that the isoprenoid, jasmonate, glucosinolate, fatty acids, chlorophyll, starch, and aromatic amino acid syntheses are located in the plastid. But I don't know if they are located in the ...
2
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0answers
77 views

Does the metabolic rate determine how fast the telomeres shorten?

In many papers one can read that telomeres may play an important role in longevity. According to Calado et al.1 the telomeres of mice are much longer than the telomeres of humans. However, mice have ...
5
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1answer
103 views

How to measure metabolic rates of microscopically small animals?

I want to measure metabolism rates in Tardigrades Metabolic rates will be assessed immediately following their exit from cryptobiosis (an animal dormant state). I know that oxygen levels is the ...
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1answer
98 views

How does the body “know” how to metabolize foreign substances

As a freshman biochemistry major, I find myself befuddled by our body's ability to perform complex chemical reactions to break down foreign substances. I can see how we would evolve explicit pathways ...
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1answer
56 views

What is the biggest facultative anaerobic metazoan known to science?

Related: What's the biggest obligate anaerobic organism discovered till now? I had always assumed that the Riftia tube worms were obligately anaerobic since they lived next to anoxic volcanic ...
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1answer
6k views

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle? I originally thought that Krebs cycle was aerobic metabolism ...
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1answer
1k views

Does THC excretion increase if urine volume increases?

In regards to the body metabolizing and excreting THC: if urination is increased as a result of drinking lots of fluids, does that mean that more THC is leaving the body? To rephrase the question, is ...
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2answers
194 views

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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2answers
170 views

How does the cell regulate different metabolic pathways?

I heard somewhere that cells use different nucleosides bound to triphosphates e.g. ATP, GTP, CTP and other modified compounds: NADH, NADPH to distinguish between different metabolic pathways and so ...
4
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1answer
42 views

Need for two oxygen sensors in E. coli

E. coli has two oxygen sensors: FNR (fumarate-nitrate reductase) and ArcBA (Anoxic Redox Control, two component control systems). FNR directly senses the oxygen, while the interaction of ArcB with ...
5
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1answer
100 views

In which way would the yeast cell cope with the excess amount of methionine in the growth media?

I guess that when there is surplus of methionine in the cell it is incorporated in the TCA cycle as a succinyl CoA, with cysteine as a by-product. But now the cell has the surplus of cysteine. What ...
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3answers
63k views

What is a coupled reaction and why do cells couple reactions?

I was wondering what exactly a coupled reaction is and why cells couple them. I read the wikipedia article as well as several others, such as life.illinois.edu but I still don't get it. Could ...
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0answers
12 views

How reactive are reduced antioxidant molecules?

When antioxidant molecules stabilize free radicals, they themselves become unstable and reactive but to a lesser degree. How reactive are these reduced antioxidant molecules? And what substance ...
3
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1answer
61 views

Can chitosan affect the absorption of unsaturated fatty acid?

I know chitosan will decrease the absorption of fat. However unsaturated fatty acid, such as DHA, is beneficial. Does chitosan effect the absorption of unsaturated fatty acid?
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3answers
1k views

What is the mechanism of oxygen uptake in E. coli?

How does E. coli uptake oxygen? Most of the literature I found is concerned with response to oxygen level supplied in the medium, as opposed to how much is actually transported inside. Can they shut ...
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2answers
678 views

In humans what is the last metabolic process to cease after death?

After death which of our body's metabolic processes will continue functioning for the longest?
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2answers
708 views

How do antioxidants affect human metabolism?

I'd like to know how antioxidants affect human metabolism and which ones are essential for metabolic processes.
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2answers
2k views

What is an irreversible reaction?

There are reactions with large Delta G negative values. Why these reactions are irreversible? As in: out of 10 steps of Glycolysis, 3 are irreversible steps. I need an explanation for why they are ...
4
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1answer
67 views

Oxidation means inflamation?

All right, I was reading article on nutrition, that focussed on content analysis of pastry-like food product for kids. I have to say that I am not sure this article would pass the imaginary smell ...
3
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1answer
16k views

Why is my faeces black in color after eating Oreos

Why is my faeces black in colour the morning after I eat some Oreos? Day 1 : Eat a handful of Oreos & the next morning your stool is black. Day 3 : Eat a handful of cocoa flavored biscuits & ...
3
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1answer
138 views

The smell from eating asparagus

I am wondering about one thing. I have read different accounts of this (prior to reading it on Wikipedia), so I am wondering. Here are the two versions I have read: asparagus leads in a certain ...
3
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1answer
286 views

Consumption of NAD+ in glycolysis

Out of 10 steps in glycolysis, only one reaction- Glyceraldehyde 3-phosphate (G3P) to 1,3-bisphosphoglycerate (PGP), uses NAD+ and thereby producing NADH. Furthermore, this very step is solely ...
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3answers
3k views

In Japan, the official average body temperature is 36.0 °C. Why so different from that of Europe?

The Japanese Wikipedia states that the average human body temperature is 36.0 °C (here,"ヒト"). The statement references the data from the Japanese government. Actually all of my Japanese friends think ...
5
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1answer
1k views

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. ...
2
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1answer
187 views

naturally occuring fatty acids

The double bonds in naturally occurring fatty acids present in our body are in cis configuration while the enzymes for beta oxidation can act on trans double bond. Then what will be the significance ...
0
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1answer
98 views

What organism most efficiently converts a given quantity of mass into heat?

Question I am trying to answer: In the popular film The Matrix, heat given off by humans is harvested as an energy source. I wondered, if this were possible, would humans be a good organism to ...
3
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1answer
166 views

Why doesn't Diabetes cause death by starvation?

The main cause for diabetes is lack of insulin in the body. Insulin is the hormone that allows body cells to absorb glucose from the blood. With out insulin, the body cells can't get glucose from the ...
3
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1answer
48 views

bacterial cell wall degradation in humans

can human degrade the D-amino acid present in bacterial cell wall, I'm confused about it i have read somewhere that human can do so.If yes than why we need antibiotic to kill bacteria???If it is not ...
4
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2answers
393 views

Where can I find a list of common enzyme cofactors and/or co-enzymes?

Where can I find a list of enzyme cofactors and/or co-enzymes, ordered by how common they are? For example, $O_2$, $H_2O$, $ATP$, $ADP$, $NAD$, should be ranked in the first places, because they ...
2
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1answer
169 views

what is the margarine metabolism in our body?

margarine is commonly used food ingredients that contribute to both inflammation and obesity , but actually I want to know the margarine metabolism in the human body I can find some resources talk ...