Questions tagged [metabolism]

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

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Should I consider [H+] as substrate in MCT transport equation?

I'm trying to model the transport of lactate in cells (in both direction via Monocarboxylate transporters): [Lactate]intra + [H+] <----> [Lactate]extra + [H+] I found some data on kinetics of ...
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Why/How do Cyanobacteria Produce Toxins?

I've been doing some research on the versatility of nitrogen-fixing cyanobacteria, particularly of the genus Anabaena, and I often run into safety hazards and have to add extra steps to my procedures ...
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Which hormones, metabolites, or other molecules build up as the day progresses, other than melatonin and adenosine?

Melatonin and adenosine reach peak levels around midnight/bedtime. I was wondering what other molecules also buildup as the day progresses. Particularly molecules that affect the CNS and/or immune ...
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What is the use of futile reaction cycling such as Fruc-P to Fruc-BP?

One rate-limiting step of glycolysis is the conversion of Fructose-6-Phosphate (Fruc-6-P) to Fructose-1,6-Bisphosphate (Fruc-1,6-BP), catalysed by Phosphofructokinase 1 (PFK 1). The reaction involves ...
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How does exercising/starved muscle import glucose (released by liver)?

Adrenaline releases glucose from the liver during sport or if starved. This glucose goes to the blood through GLUT2 transporter. But how does it get transported into the muscle cells? GLUT4 is the ...
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Is this statement about caterpillars right?

I've read in lots of sites statements like the following from the Sciencing site "Inside the chrysalis of a butterfly, a caterpillar's body turns to liquid form and it is rebuilt as a butterfly." ...
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Can muscles remake pyruvate from lactic acid, or does it have to go to the liver in the Cori cycle?

When the muscle is exercising, and only anaerobic respiration is done, pyruvate -> lactate to regenerate NAD+. Lactate is then transported out of the muscle and into the liver, to regenerate glucose, ...
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What relation do glycerol-3-P DH and acyl-CoA DH have with Complex II of the ETC?

I am sorry if this may be a purely definitional/nomenclature question. Complex II of the electron transport chain (ETC) would be succinate dehydrogenase, transporting electrons to ubiquinone (and ...
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What makes the cytoplasm a reducing environment?

It is known that the cytoplasm is a "reducing" environment, where disulfide bonds cannot form (will soon be reduced to 2 cysteines) [I'm not putting a link as this is a fact in many biology textbooks]....
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Does an FAD:FADH2 ratio exist in the cytoplasm? (similar to NAD+:NADH ratio?)

I have learned about a lot of enzymes/proteins which are covalently bound to FAD, and use this as an oxidising agent. In vivo, FAD is (almost) always protein bound (very low concentrations of free FMN/...
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Is there any other sources of hydrogen carriers for the Electron Transport Chain other than the 3 main metabolic pathways?

I am learning about the 4 main metabolic pathways for cellular respiration. I learned that NADH and FADH2 hydrogen carriers are essential in the Electron Transport Chain, because they deposit their ...
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Are there any known microbes capable of living in almost pure carbon dioxide?

Some bioengineering is investigated in high carbon dioxide environments. Are there any microbes like bacteria or Archaea capable of living and multiplying in such environments?
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What is a flux control coefficient?

In metabolic control analysis, a number of coefficients are defined, including the flux control coefficients. How is this coefficient defined and what does it measure?
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Do plants take in the same amount of CO2 as they release?

There are many claims in the media that trees remove more carbon dioxide form the atmosphere than they release back into the atmosphere. By what chemical pathway can this occur? The law that matter is ...
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How much energy does a small spider expend per day just waiting for its web to vibrate?

Roughly speaking, a small, complex electronic circuit or IC might sit in "sleep mode" using a current of roughly 1 µA (e.g. 1, 2), thereby using roughly $3\times 10^{-6}$ Watts, and that ...
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In ketogenesis, why is acetacetyl-CoA not directly hydrolized to acetoacetate in ketogenesis?

Ketogenesis pathway maps show acetoacetyl-CoA converted to HMG-CoA and only then to the first ketone body acetoacetate. Why this detour instead of directly hydrolyzing off the CoA to get there in a ...
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Any phyla in Animalia that does ammonia assimilation?

A key step in nitrogen metabolism is the initial assimilation of inorganic ammonia into amino acids. Are there phyla within Animalia that do assimilation of ammonium (NH4+)? Phyla with symbionts from ...
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Can erythrocytes Function without plasma?

my title is not very specific. So i will proceed to clarify it. I am trying to make sure that the only blood cells in a sample are Erytocytes, since i want to evaluate their metabolism, I am aware ...
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Why do patients with type 2 diabetes not show the body wasting seen in type 1 diabetics?

Type 1 diabetes results from the destruction of the cells in the pancreas that produce insulin, while type 2 diabetes is characterized by so-called "insulin resistance", presumably a reduced ...
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Can the human body store protein?

I am interested to know if a human body can store protein. Absolutely for the bodybuilders, does it really matter if they divide their protein consumption during the day or eat all of it in one meal ...
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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 ...
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Can heterotrophs use anabolism to obtain energy?

With that question I mean: directly. Please bear with me, as I don't know much about Biology or Chemistry (those are my main difficulties while studying). I know that energy that biological beings ...
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How does temperature affect metabolism of warm blooded animals (homeotherms)?

In cold blooded animals (Poikilotherms) the temperature has a profound effect on metabolism. When the external temperature is raised a corresponding rise in internal temperature followed by a rise in ...
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Looking for Older KEGG global map

I'm looking for the global KEGG map from around 2017, so I can follow the corresponding map in this paper (Figure 4) easier. While the current global KEGG map mostly maps, I'm trying to easier figure ...
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Is there an evolutionary reason for the 5 electron transport complexes in plants and animals?

The electron transport chains of both the light reactions of photosynthesis (in plants) and oxidative phosphorylation (in animals) both contain 5 complexes including ATP synthase, as shown below. ...
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Is the lac operon repressed in the presence of both glucose and lactose?

In the presence of both sugars (glucose and lactose) will there be repression of the lac operon completely? I know that more glucose means less cAMP --> less CAP --> less positive regulation, and ...
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Regulation of the TCA cycle and glycolysis by adenine nucleotides

Why is the tricarboxylic acid cycle regulated by the ADP/ATP ratio as stated in the following quote : Isocitrate dehydrogenase is allosterically stimulated by ADP, which enhances the enzyme's ...
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How much does 10g of glucose raise the blood glucose level?

If you would calculate it: ~5 liters of blood = 50 deciliters 10g glucose = 10000 milligram so the glucose level raises by 10000mg/50dl = 200mg/dl However, it is known that ingesting 10g glucose ...
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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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What happens to glucose taken up by the liver in type 1 diabetes?

Type 1 diabetes is caused by insufficient insulin production. Unlike in muscle and adipose tissue (GLUT4), glucose uptake by the liver is by GLUT2 and thus insulin-independent. Consequently, under ...
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When is the lactase in lactose-free milk active?

Recently we have started suspecting that one of our children has hypolactasia (lactose intolerance), and so accordingly I have had my first exposure to lactose-free dairy- and dairy-like products. In ...
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Why does the liver produce ketone bodies instead of exporting acetyl-CoA from beta-oxidation for use elsewhere?

Under conditions of low oxaloacetate in the liver, acetyl-CoA that cannot be oxidised in the TCA cycle is converted to ketone bodies, which can then be exported for use as fuel in non-gluconeogenetic ...
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How does coffee cause calcium loss in our body?

Recently on radio a doctor advices to reduce the consumption of coffee as it leads to calcium loss(as my mother described). My initial response was: How could such thing be possible? What kind of ...
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How to calculate grams of fat used during hibernation?

In Humphries et al. 2002. Nature, the authors report number of grams of fat bats use during hibernation. However, their equations results in values in mlO2/g. How can one convert the energy ...
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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. ...
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quantification of glucose utilization in different metabolic processes

Glucose is commonly associated with ATP production. However, only a small fraction of glucose is utilized this way. The intermediates of glycolysis, TCA cycle, etc. are precursors to various ...
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How do anaerobic bacteria produce ATP for their own cellular activities?

Anaerobic bacteria utilise glycolysis: Glucose + 2 P + 2 NAD+ => 2 ATP + 2 H + 2 NADH + 2 H2O + 2 Pyruvate followed by fermentation: Pyruvate + NADH => Lactate + NAD+ The resultant NAD+ formed ...
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What is the relationship between cell size and metabolism?

What effect does a bigger cell have on its metabolic activity? I understand that bigger cells need more energy, but surely smaller cells may have high metabolic rates too due to their efficiency?
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What happens if an enzyme stops working in the body?

For example, if the enzymes in the digestive system stop working will the digestion still occur as enzymes are only catalysts for the reactions. Thank You
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A biological system to measure time

First of all I am a physicist, so I apologise for my non-existent understanding of basic biology. However, I have what I think is an interesting question and this seems like a good place to ask it... ...
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During weight loss, do we inhale more oxygen?

During weight loss, triglycerides which are composed of carbon, hydrogen and oxygen, are broken down. During respiration, the inhaled $O_2$ is bonded to a carbon atom to form $CO_2$ which we exhale. ...
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Why is urea not converted to ammonia in the body?

After the liver processes metabolites to produce urea and other by-products, these travel in the blood to the heart, then they are oxygenated, and some travel through the renal artery to the kidneys. ...
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How important is getting enough glucose for maximal brain performance / cognition?

I know from many studies that have been done, that resting versus active use of the brain has relatively similar overall energy expenditure levels. On the other hand, however, we know that the brain ...
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Does the arrangement of amino acids in a protein matter for nutrition?

Let's say there are two diets, consisting of entirely different proteins. If you split up all of the proteins from one day of each diet, you'll get the same set of amino acids and the same count of ...
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Does Glycolysis produce lactate, or pyruvate?

EDIT- Somebody suggested that this is the same question as this, it isn't. This one is asking about the definition of glycolysis. That one was asking about the definition of fermentation. Does ...
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About the definition of ketogenic amino acid

I am studying biochemistry and have been looking at metabolic network diagrams showing the different intermediates of glycolysis and the citric acid cycle that amino acids can be converted to. I have ...
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Can you predict what the metabolites of pipradrol would be? Are they similar to those of methylphenidate? [closed]

As these drugs are structurally very similar, I am curious about how the body would handle them. Ritalinic acid is a major metabolite of methylphenidate, but that's about all I know. Thanks ...
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May two reactions, that share the same reactant, fire at the same moment?

I'm studying metabolic networks from a bioinformatics point of view, but I guess my question is pretty biological so I thought that maybe here I could get the best answers. So, as the title says I ...
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Cause of Obesity

Considering that the sequestering of 'persistent organic pollutants' [POPs] by adipose tissue is now established (see Toxicological Function of Adipose Tissue: Focus on Persistent Organic Pollutants ...
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Does food lose some of its mass in form of energy during metabolism?

I had an argument with someone. I argued that when a cat eats 1 kg of food, the sum of subsequent output (poo + pee + sweat + change of body mass) must be equal to 1 kg. My opponent argued that the ...

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