Questions tagged [metabolism]

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

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Is it wrong to consider an allosteric inhibitor a non-competitive inhibitor?

Supose Caspase-1 is allosterically inhibited. Since the inhibitor is not binding in the active site but instead in the allosteric binding site, can I conclude it is a non-competitive inhibitor?
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How can grass-fed livestock generate fat?

How can herbivorous cattle get fat? These animals eat only grassy substances, think of cattle, buffalo, goats etc. For example, wheat grass contains 0% fat, and its nutritional value is limited to ...
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Misincorporation of dUTP into DNA?

Uracil, the RNA base, has been replaced in DNA by thymine, (which has the same base-pairing with guanine). However the synthesis of dTTP (more usually written TTP) requires dUTP: To what extent is ...
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Effect of cold showers after intense training

What is the effect of cold showers after very intense training (body fully covered in sweat, high pulse, increased body temperature)? I'm especially interested in how it affects perspiration.
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Regulation of the concentration of precursors of DNA and RNA synthesis

What is the specific cellular process for regulating the amount of the four DNA bases (adenine, thymine, cytosine, and guanine) that are present in the cytoplasm of a cell? Basically, how do the cell'...
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Protein diet composition

I have read that non veg food are better for proteins while veg food is deficient in either one or other protein. If it is so are herbivores protein deficient always in case of animals as well as ...
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Is the amount of cholesterol the body produces affected by how much cholesterol you take in with food?

In the past I've been told multiple times that if you don't eat foods containing cholesterol, your body will increase its production of cholesterol to balance out the lack of nutritional cholesterol. ...
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Excercise and fitness in old age [closed]

I have seen so many news and study online, saying exercise keeps body healthy in old age and keeps us fit? how is this possible normal tear and wear will become more with activity hence more mutation ...
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Excess protein consumption effect on kidney

How does excess protein consumption through food as well as through supplements affect body especially kidneys? Why it is advice to consume low protein diet during summer ?
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What is the fate of NADH produced in the liver during oxidation of lactic acid?

NADH (‘reduced NAD’) is produced during the oxidation of blood lactate in the liver. Glycolysis requires NAD+ (‘oxidised NAD’), whereas gluconeogensis requires NADH. However the NADH is apparently not ...
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Why does lactate build up prevent a further increase in the speed of an athlete?

This question was triggered by an exam question that I was doing on the following paper (Q2 part (b)(i)): http://qualifications.pearson.com/content/dam/pdf/A%20Level/Biology/2013/Exam%20materials/...
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fast metabolism and law of conservation of energy

Usually if person take more calories with food than he spends, he is gaining weight. But if he has fast metabolism, his weight stays the same. Where these calories go? Maybe food is not completely ...
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Is palmitic acid really that dangerous?

According to Wikipedia, "Palmitic acid is the most common saturated fatty acid found in animals, plants and microorganisms. It is also the first fatty acid produced during fatty acid synthesis and is ...
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Violation of the law of energy conservation between photosynthesis and respiration?

For the production of one glucose molecule in the Calvin cycle a plant uses 18 molecules ATP, but when the same glucose molecule is oxidised — first in the cytoplasm and then in the mitochondrion — it ...
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How does human body keep track of its age? [closed]

How does the human body knows that it's time for a event that happens around a certain age like puberty or something that's periodic like menstruation or gestation time of 9 months? Please note I'm ...
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Why is a magnesium ion essential for ATP activity in enzymic reactions?

The Wikipedia entry on Magnesium in Biology includes the following: ATP (adenosine triphosphate), the main source of energy in cells, must be bound to a magnesium ion in order to be biologically ...
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Fatty acid oxidation in adrenal medulla?

Why adrenal medulla can not utilise fatty acids for generation of energy? What could be the benefit for not having ability to use fatty acids? Refrence 1 Refrence 2
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Why is glycerol kinase absent from adipocytes but present in the liver?

Why don't adipocytes have the enzyme, glycerol kinase? Wouldn’t it be more efficient for them to utilise glycerol present to synthesize triglycerides than to get it from the liver? So what is the ...
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What is the brain's preferred energy source? Glucose or ketones?

As with all cells in our body, I know that the brain can get fed from both glucose and ketones, so my question is, given both of them, which one would the brain prefer to utilize first?
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Do pregnancy and breast feeding increase basal metabolic rate?

Since pregnant or breastfeeding women have extra nutritional needs, does that mean they have a higher BMR? Why I thought the conclusion would be sensible: Since BMR is the energy needed to perform ...
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How is the rate of gluconeogenesis controlled in the cell?

As far as I am aware, all steps in glycolysis are readily reversible except the phosphorylation of glucose, the phosphorylation of fructose6 phosphate, and the phosphorylation of phosphoenolpyruvate ...
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Organism-specific Kegg Pathway: Must all boxes be high-lighted/present for a reaction to occur?

I'm new to using Kegg and not sure how to interpret the position of the pathway enzymes in the pathway that I'm looking at. More specifically: If all boxes (of KOs) must be present/colored green or ...
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How to determine the fastest metabolism ? [closed]

Which is the fastest metabolism ? Fructose metabolism or Glucose metabolism
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If a fully functional lab grown pancreas can exist, can it be used as a cure for type 2 diabetes?

Is it approximately equivalent to say that if a fully functional lab grown pancreas exists, then a way to cure Type 2 diabetes could soon exist? Recently I've already checked out that only the ...
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Why is the hexose monophosphate shunt called a direct oxidative pathway?

Why is the hexose monophosphate shunt (pentose phosphate pathway) called a direct oxidative pathway( Ref. Biochemistry by Satyanarayana , 4th edition, pg.no: 244) , even though oxygen molecule is not ...
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Normal TSH Levels in Hyperthyroxinemia

When it comes to hyperthyroxinemia, how is it possible for TSH to be normal when there is an elevated thyroxine concentration? What I know so far is that it is caused by a mutation in the Human serum ...
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Is excretion always necessary? [closed]

I know we defecate or/and urinate to rid ourselves of toxins and excess undigested food. If I was somehow able to get exactly what my body needed to function. Let's say that I create a pill (or ...
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Origin of the biochemical term, Pi (inorganic phosphate)

I would like to know when the term Pi (inorganic phosphate) was introduced in the representation of biochemical reactions, how it was originally defined, and the justification given then for using it ...
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How do poiklotherms survive at different temperatures even though enzymes work at specific temperature?

Since enzymes have an optimum temperature at which they are able to catalyze the reaction best and increasing the temperature above optimum can even damage them, how do poikilotherms survive as they ...
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Do Alicyclobacilli produce carbon dioxide?

Do Alicyclobacilli, especially guaiacol producing ones, still produce carbon dioxide? Alicyclobacillus spp. are well known spoilage organisms in the fruit juice industry. Apparently there is no "...
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Production of $CO_2$ basal metabolism test

Can the production of $CO_2$ be used as a type of basal metabolism test? Explain. The answer to this is obviously yes, but I don't know how to explain it. Would the following be a good explanation? ...
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Why is GTP, not ATP, produced in Gluconeogenesis & TCA Cycle?

In both gluconeogenesis and the TCA cycle, there is a point in each that GTP is produced instead of the usual ATP. My question is why GTP and not ATP for these 2 specific steps?
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Mammal size and capillary wall thickness

How does capillary wall thickness vary with the size of the animal? Background/context of question: Of the following, Figure 1 is most consistent with the fact that, in general, smaller mammals have:...
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What is the ultimate source of ADP/ATP in humans?

I am teaching myself Cell Biology from the internet. Despite my usually good Googling skills, I'm stuck in a loop with this question. Q: What is the source of ATP? A: ADP Q: What is the source of ...
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How do red blood cells obtain energy without mitochondria? [duplicate]

RBCs don't have mitochondria so there is no Respiratory chain in them. But how does they get energy from Lactate. Because Lactate produce NADH which gives energy only in respiratory chain.
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Why do some tissues have insulin-dependent glucose transporters and others not?

Insulin upregulates GLUT-4 glucose transporter insertion in skeletal muscle and adipose tissue. But there are many tissues in the body that use insulin-independent glucose transporters (like GLUT-3 in ...
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Should heart-to-body energy consumption ratio equal oxygen consumption ratio?

The human heart pumps oxygen to the body, and the heart itself requires oxygen. Both the body and the heart use energy, usually expressed in calories or ergs. If we look at the energy consumption (...
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Does food really give our bodies the energies that we have determined by burning them in the lab?

You are likely to have come across numbers like sugars 17kJ/g (4kcal/g) as the energy supposedly available to our bodies after eating. Yet these values have been determined using very artificial means,...
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Why isn't acetyl-coA an entry point for gluconeogenesis?

The process of gluconeogenesis starts from various possible precursors - plausible entry points like, Pyruvate, OAA, Fumarate, Propionate (as succinate) and alpha-KG. It is important to note that, ...
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Is ATP produced in a different manner during glycolysis from that generated by the Krebs Tricarboxylic Acid Cycle?

The ATP in glycolysis is produced in the cell cytoplasm but that from the Krebs Cycle is produced in the mitochondria. The mitochondrial membrane contains an ATP-synthase protein complex that ...
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What are the obstacles to “refitting” the human body's metabolism?

As a layman, I understand the problem of rising obesity like this: In the old times, humans could never get enough food, thus they would eat whatever they could get. This "program" is encoded in our ...
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Is there evidence to suggest that sleeping requires more energy than watching TV?

I have heard the claim: sleeping requires more energy than watching TV. I have heard the counter-claim - watching TV requires large amounts of energy. My question is: Is there evidence to ...
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Requirement of energy for metabolic processes

Sorry if this is too elementary, but can someone explain why the following reaction can occur without a net influx of energy from some other process? $C_6H_{12}O_6 + 6O_2 \to 6 CO_2+6H_2O$ And why ...
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Relative roles of ATP and NADPH in anabolic and other processes

Chemistry isn’t my strong point, but I’m trying to understand why NADPH is said to be the main agent necessary for anabolic reactions, and if NADPH is used for anabolic reactions what is ATP used for? ...
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At what total rate is water used in metabolic processes over the entire biosphere?

A recent column on "The Straight Dope" website discussed the idea that water molecules are largely cycled around through the water cycle, and that therefore the water molecules that come out of your ...
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Rate of production of enzymes in human [closed]

In the metabolic pathways, each of the reaction needs an enzyme(protein) in order to occur successfully. Is there any quantitative measure that can be associated to this enzyme? Like synthesis rate of ...
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Would short term increases in oxygen lead to beneficial effects?

After some thinking, I am wondering if having a 30% atmospheric oxygen concentration (or some other concentration) for a short time would increase the regeneration of energy in a body? It seems like ...
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What is the source of the electrons generated in the Krebs cycle?

In the Krebs cycle, where do the hydrogens and electrons that NAD+ and FAD accept come from? It seems that citric acid only loses two hydrogens because it starts out with eight hydrogens and then ...
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What would the presence of a hub metabolite in a metabolic pathway signify?

Say I have a metabolic pathway, consisting of multiple metabolites and reactions. On analyzing the pathway I find that among all the metabolite, one metabolite is the hub metabolite (hub metabolite is ...
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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 ...