Questions tagged [metabolism]

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

Filter by
Sorted by
Tagged with
1 vote
1 answer
13 views

Glycemic Index and AUC Curve: why do two different foods have differing numbers?

The AUC Glucose/Blood Level curve Integral (area under curve) is used to calculate the Glycemic Index of certain foods. I have a question on why two sample foods with the same mass of carbohydrates ...
  • 207
0 votes
0 answers
9 views

Fat Oxidation in relation to MaxHR and V2OMax? Glucose to brain over range?

It's my understanding that maximum body fat oxidation occurs between 47-75% of V2OMax and 70-80% of Max Heart Rate. I did a test of this theory on the treadmill, using it's metrics, and found that I ...
  • 207
0 votes
1 answer
34 views

Human Body's rate of conversion of carbs, protein and fat into energy?

I understanding there are some complicated processes, but I'm interested in generally how fast the body converts certain chemicals into energy and the period of time this conversion occurs. I'm ...
  • 207
0 votes
1 answer
30 views

Calculating the Glycemic Index using an AUC Glucose/Blood curve?

Does anyone know the mathematics to calculate the Glycemic Index using a AUC Glucose/Blood curve? Is there an article documenting the process? I understand that algebra and integral calculus is ...
  • 207
1 vote
0 answers
15 views

What prevents the diffusion of proton gradient in Gram (+) bacteria

The proton gradient in bacteria is important to power FTPase and flagella. How do Gram (+) bacteria maintain a proton gradient without a periplasm (Gram (-)) or intermembrane space (mitochondria). Why ...
6 votes
0 answers
69 views

What is the share of body energy that the brain consumes? Is 20% reliable?

"20% of the energy at only 2% of the weight" is a frequently regurgitated factoid. More precisely, it should read: 20% of oxygen consumption. The problem starts when one looks into the ...
  • 538
1 vote
1 answer
65 views

Why do highland/alpine plants require a drop in night temperatures to thrive?

There are mountain plants which require a drop in nightly temperature (many Nepenthes, Heliamphora and orchids for example). A non-specialist explanation is that the plants die of "starvation&...
  • 111
0 votes
1 answer
30 views

How does red light change the cellular mechanism in cells?

As winter approaches and the amount of sunlight decreases in the northern hemisphere, I have been reading about red light therapy and its supposed beneficial clinical effects. Yet there is no much ...
0 votes
0 answers
15 views

Are dendrimers synthesized by living organisms?

Dendrimers are beautiful https://en.wikipedia.org/wiki/Dendrimer They are used to deliver drugs and model branched molecules. But everywhere they are strangers to a living cell. It is hard to believe ...
0 votes
0 answers
16 views

Have some lower order organisms evolved to grow below the freezing point of water?

I just learned that water sublimates, which prompts me to ask: Can lower order organisms (e.g. bacteria / fungi) grow below the freezing point of water?
  • 133
2 votes
1 answer
129 views

Where in the biological realm is vitamin B5 chiefly produced?

Can yeast produce pantothenic acid (vitamin B5)? Do bacteria efficiently produce it? Or does it only come from plants? The Wikipedia page for pantothenic acid doesn’t seem to answer the question (...
  • 133
1 vote
0 answers
30 views

What is the supposed added benefit of ketosis for weight loss, if adipose tissue fat is utilized both in ketosis and in normal state?

Some descriptions of ketogenic diets, claim they are effective for weight loss because the body switches to 'burning fat' for energy, instead of using carbs. However, the description of the ...
1 vote
0 answers
23 views

Can organisms grow on acetic acid?

Can organisms grow on acetic acid and water (with <1%, all inorganic, impurities), i.e. using acetic acid as a carbon / energy source? If so which concentration of water would it start at? (...
  • 133
0 votes
0 answers
21 views

What is the conjugation capacity of the liver?

Our liver conjugates 250-300 mg bilirubin per day under normal circumstances but it is capable of conjugating much more. What is the upper end per day after which it won’t be able to conjugate leading ...
0 votes
0 answers
29 views

How to Scale Metabolic rate and drug dosage according to Mass?

I was reading a book "Biology and evolution of Crocodilians" by Gordon Grigg and David Kirshner. And I can't understand the part about metabolic scaling no matter which method I tried I can'...
2 votes
1 answer
240 views

Heart rate and Metabolic rate relationship

Metabolic rate in humans can be approximated using the Penn State equation. It can also be estimated using direct and indirect calorimetry. According to Kleiber's law, metabolism scales across species ...
  • 41
1 vote
0 answers
26 views

Does succinic acid provide any caloric value in humans?

Would the ingestion of pure succinic acid provide any caloric value in humans? I couldn’t find any nutritional information about it via Googling, but I read on Wikipedia that it’s converted into ...
  • 11
2 votes
1 answer
99 views

Do Mannose and Galactose yield the same products as Glucose when oxidized?

I just started learning about sugar metabolism, when I saw how other monosaccharides enter the glycolytic pathway. Mannose enters glycolysis as fructose-6-phosphate at the expense of 1 ATP, then ...
2 votes
1 answer
84 views

Are there irreversible metabolic reactions that can happen in opposite ways depending on the cellular conditions?

Irreversible reactions are thermodynamically irreversible, not microscopically irreversible. "Irreversible" here means the reaction happens "out-of-equilibrium". It is a ...
  • 215
1 vote
0 answers
34 views

Walking or running makes me consume 200 to 550 kcal/h, that's true, but always 68 to 72 kcal per kilometer whatever the effort done. Why?

My connected watch tells me that when : I'm walking I'm consuming 200 - 250 kcal per hour, running: from 500 to 550. and this is ok. But it also tells me, that how many kilometers are my trips, I'm ...
2 votes
1 answer
53 views

Is the pyruvate dehydrogenase reaction considered part of the Krebs Tricarboxylic Acid Cycle?

I’ve encountered questions where I’m asked to find out the CO2 released, the number of oxidative carboxylations etc. in the Krebs tricarboxylic acid cycle. I always include the pyruvate dehydrogenase ...
0 votes
1 answer
82 views

Do plants digest substances they ingest?

I was thinking about plants having no digestion system (is that true at all?) and my conclusion was that they only ingest substances that they can use like that or that they can transform into usable ...
4 votes
0 answers
32 views

Adh2 promoter in saccharomyces cerevisiae

I'm looking at expressing a protein in saccharomyces cerevisiae using the Adh2 promoter. My understanding is that the gene will be repressed by the presence of glucose, but when glucose runs out it ...
4 votes
1 answer
137 views

Does the biofilm formation hinder photosythesis?

In photosynthetic bacteria such as Cyanobacteria, Synechocystis sp. PCC 6803. The bacteria need access to both light, CO2, and water to perform photosynthesis. However, in thick biofilm structures (e....
2 votes
1 answer
100 views

After digesting food, where does the energy go before being stored by the body?

I'm trying to piece together a simplified model on how the energy flows in the human body. From what I understand: We store enough ATP for around 2 seconds of maximum exertion We store enough ...
  • 227
1 vote
0 answers
29 views

Is Acetyl-CoA ever transported out of the cell, and in that case how?

Acetyl-CoA is sometimes formed as a result of protein katabolism. Certain cells (in the muscle for instance) can't use Acetyl-CoA to synthesize fatty acid. If there is no immediate need for energy, ...
  • 221
1 vote
3 answers
5k views

Why are 6 turns of the Calvin cycle needed to make one molecule of glucose?

I‘ve read that 6 turns of the Calvin cycle are required to make 1 glucose molecule. But, 3CO2 and 3RuBP are used in one cycle and 6 triose phosphate is produced. Only 5 triose phosphate molecules are ...
0 votes
0 answers
32 views

How can we explain that glucose at its concentration less than a Km for the transporter enters the peripheral circulation?

I'm studying biochemistry from Kaplan's book. In it, I found the following paragraph in the topic on glucose metabolism: "GLUT 2, a low-affinity transporter, is in hepatocytes. After a meal, ...
1 vote
0 answers
97 views

Do quantum mechanical effects such as uncertainty, tunnelling and entanglement play role in the electron transport system of respiration?

The electron transport system of aerobic respiration involves an extensive pathway of electron and proton transfer from one centre to another. Now, since they are quantum mechanical particles, shouldn'...
1 vote
0 answers
64 views

Why does ATP act as an allosteric inhibitor of glycogen synthase?

Why is ATP an allosteric inhibitor of glycogen synthase? Wouldn't high levels of ATP in the cell mean that the cell has sufficient energy, and in this case wouldn't excess glucose be stored as ...
6 votes
1 answer
476 views

Is there a function for urea in sweat?

In ureotelic organisms, ammonia is converted to urea for excretion primarily in the liver and, to a lesser extent, in the kidneys. However, sweat also contains trace amounts of urea. Is this small ...
  • 1,260
-2 votes
1 answer
49 views

How does exercise cause weight loss if the corresponding chemical reactions have the same mass on the LHS and the RHS?

How does weight loss take place in the body during physical activity, given that the corresponding chemical reactions would have the same mass on the left hand side and the right hand side?
4 votes
0 answers
49 views

Isolated mitochondria in glucose rich solution, what happens to ATP generation?

I'm taking intro to biology course this year, and I was thinking about this question. Isolated mitochondria were placed in a glucose rich solution. (With ADP and Pi). How would this affect the ATP ...
  • 41
5 votes
1 answer
150 views

Concentration of active ingredient

For some time now, I have been wondering why, when a tablet is taken, the concentration of active ingredient undergoes an exponential decrease after the maximum concentration value in the blood is ...
  • 153
11 votes
0 answers
82 views

What actually kills a plant that requires winter dormancy if it is kept indoors all year?

In bonsai practice, beginners will commonly purchase a juniper (often Juniperus procumbens 'Nana'), which is an outdoor tree, and keep it inside all year. The tree invariably dies. It is commonly ...
  • 219
4 votes
1 answer
257 views

Why is fructolysis independent of glycolysis?

In glycolysis, glucose is converted to fructose-6-phosphate before further breakdown. However fructose, instead of being phosphoryated to fructose-6-phosphate by glucokinase (and thereafter to ...
0 votes
0 answers
36 views

Maximum Allometry of aquatic mammals omitting Kleiber's Law

As far as I understand, blue whales cannot get any physically larger due to the extremely demanding caloric intake it has on consuming large quantities of krill, not due to any other physiological ...
4 votes
3 answers
182 views

Production of plant derivatives using genetic engineered micro-organisms

I saw a Thought Emporium video where spider silk was produced by genetically modifying yeast. I have also read about companies making vanillin (vanilla flavour) using this technique. I am curious to ...
6 votes
1 answer
300 views

Pyruvate dehydrogenase: Apparently anomalous NAD/FAD redox reaction

Below is the mechanism for the reactions of the pyruvate dehydrogen complex, which oxidatively decarboxylates pyruvate and transfers the acetyl group to coenyzme A for further metabolism in the Krebs ...
3 votes
1 answer
35 views

What terms or concepts are used to describe the morning metabolic phenomenon involving glucocorticoids, glucose, and blood pressure?

A recent conference report described using a vaccine-based strategy to blunt a surge of high blood pressure that occurs between 5 and 8 a.m. Apparently most heart attacks and strokes occur during ...
  • 2,435
1 vote
1 answer
45 views

Why hypothyroidism causes body ache?

In the condition of hypothyroidism the Thyroid Stimulating Hormone level is high in individuals. What signalling/metabolic pathway mediates this sensation of pain which is mostly experienced in feet ...
0 votes
1 answer
54 views

How is the glycemic index computed from a blood sugar curve?

The definition of the glycemic index is often given as the area under curve (AUC) of their two-hour blood sugar response. However, it's essentially meant to be a measure of whether food causes a fast ...
0 votes
1 answer
343 views

How do cellular conditions change the Gibbs free energy of a reaction?

How do cellular conditions change the Gibbs free energy of a reaction? Taking glycolysis as an example, how exactly would cellular conditions affect the free energy released from this reaction?
  • 105
0 votes
0 answers
18 views

What is the energetic costs in KJ/g NH3 for nitrogenase fixation

What is the energetic costs in KJ/g NH3 for nitrogenase fixation. I want to compare Haber-Bosch vs nitrogenase. How would I force the biological stochiometry of 8e- electrons into an energy quantity. $...
  • 21
0 votes
0 answers
49 views

Do all anabolic reactions involve condensation?

I know that condensation is one example of an anabolic reaction (building macromolecules from monomers), but do all anabolic reactions involve condensation? Or is there an example of an anabolic ...
  • 111
-2 votes
1 answer
87 views

What is a metabolite? [closed]

I am a mathematician and work on metabolic networks as networks. But I could not find a proper definition for a metabolite? Are they organic molecules? can a gene or a protein also be a metabolite?
  • 13
1 vote
1 answer
633 views

Relation/difference between metabolism and cellular organisation

In the highlighted paragraph from NCERT textbook, they mention that cellular organisation is the defining property of life forms while metabolism without exception is also the defining property of ...
4 votes
1 answer
112 views

Apparent paradox in Glucagon action

Glucagon stimulates glycogenolysis and gluconeogenesis, thus increasing the plasma glucose concentration — so that tissues get enough glucose in the fasting state. However glucagon also inhibits ...
  • 607
8 votes
1 answer
361 views

Why are children more active than adults?

I have observed that children are usually more active than adults. For example, in the morning they get up and start playing, they have their lunch and get up and start running, while as adults they ...
  • 201
-1 votes
2 answers
201 views

Do identical twins have the same metabolism rate at birth? [closed]

Will monozygotic twins defecate at the same time if fed at the same time during the first weeks of life? They should have the same genetics (and epigenetics) since they are monozygotic and the same ...
  • 943

1
2 3 4 5
11