Questions tagged [energy-metabolism]

Energy metabolism is the set of defined biochemical transformations by which living organisms generate energy (in the form of ATP) from nutrients.

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Placement of an insectivorous plants in a food chain?

Where can we place an insectivorous plant such as Venus flytrap in a food chain, first or other trophic levels.... because it is a producer as well as consumer?
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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 ...
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What is the relationship between muscle energy consumption, the period over which the contraction occurs and the mechanical work performed?

I'm asking this question with some basic knowledge of physics and general fitness. Suppose you are lifting a still object with mass $m$ from height $h_1$ to height $h_2$ with an arbitrary (straight or ...
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Do microorganisms produce more glucose in their extracellular environment than they need? Why?

Trichoderma reesei breaks down cellulose into beta and alpha glucose by secreting cellulases. Why do they produce far more glucose then they need when incubated with susbtrate?
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Does 1kg of lettuce have more energy than 1kg of beef?

Given that each trophic level of the food chain has a decrease of 90% of available energy, would it be fair to say that 1kg of lettuce has more energy than 1kg of beef? If it's not true, can you ...
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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'...
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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 ...
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Besides fats, proteins, and carbs, what compounds can the body use for energy?

What kinds of chemical species that do not belong to the category of fats, carbohydrates or proteins can the body metabolise? Clarifications: By metabolise, I mean extract energy from (e.g. as ATP). ...
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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?
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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 ...
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Which enzymes use ATP?

It is well known that there are many enzymes which use ATP in their function, and any enzyme that work against an energy gradient need to have that energy supplied from somewhere, but just as well ...
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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. $...
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Comparing maintenance energy costs of plant biomass vs bacterial biomass

Im interested if anyone has an idea if this research has been done or how you would approach it. What is the energetic maintenance cost of (e.g) 2kg of some given bacterial cells vs 2 kg of a plant (...
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Where are the ATP synthases synthesised? [duplicate]

The nano-machinary of energy production ATP synthase is well known to exist on mitochondrial inner membrane and chloroplasts. But how and where are they formed or synthesised ?
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What determines whether a reaction using ATP produces ADP or AMP?

Most reactions using ATP seem to involve: ATP → ADP + Pi but in some the reaction is ATP → AMP + PPi followed by hydrolysis of the pyrophosphate: PPi → 2Pi Is there any principle that determines which ...
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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 ...
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Under which conditions is human energy consumption minimized?

Including but not limited to: body state consumed food composition state of the digestive tract diseases wounds sleep coma, etc.; death excluded environment state temperature light pressure, etc. ...
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Reverse oxidative phosphorylation?

I noticed that all of the cellular energy production methods that I covered have a fixed ratio of ATP to NAD(P)H out. For example, in the combined process of glycolysis, pyruvate oxidization, and the ...
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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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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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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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Is molecular oxygen (O₂) consumed in any process (in humans) other than acting as an electron acceptor for the ETC? [duplicate]

I know that molecular oxygen (O2) serves as the electron acceptor in Complex IV of the electron transport chain, which maintains the proton gradient that produces ATP for, as far as I know, every cell ...
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About the mechanism of coupled reaction/metabolism with ATP

I am not in the field of biochemistry so this may be a rookie question or misconception. I heard occasionally about the energy "released" from ATP hydrolysis fueling (endergonic) biological reactions....
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Understanding entropy and the second law of thermodynamics as involved in metabolic processes

My AP biology textbook, (the 10th edition of Campbell Biology) states entropy as being the disorder or randomness of the atoms involved in any matter, but Khan Academy says that this example isn't ...
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What is the human energy consumption by organ?

The human brain uses about 25% of the human body's metabolic energy. How are the other 75% spent, in terms of portioning to its various systems? I thought this could be answered by a simple search, ...
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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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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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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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5 votes
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Why have plants evolved to photosynthesize glucose instead of another molecular compound?

I think this question can be broken down into two sub-questions: Why do plants produce $C_6H_{12}O_6$ as opposed to another molecule following the formula of $C_nH_{2n}O_n$? Why not $C_8H_{16}O_8$, $...
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What are the bare minimum nutrients required to survive as a human?

I am trying to determine the bare minimum nutritional requirements to survive as a human, ignoring energy (caloric) requirements. Another way to ask this question is: What elements can humans not live ...
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How does the human body extract energy from ethanol?

I was talking about alcohol and obesity with a colleague. I always thought the only cause of that is the sugar that is found in most alcoholic beverages. But my colleague pointed out that ethanol ...
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Is there a link between brain's energy consumption and human experience?

I was read the article (in Scientific American Mind) about energy consumption of brain. There are: Say you are learning a new skill—how to juggle or speak Spanish. Neuroscientists have made the ...
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1 answer
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How does shortage of oxygen halt the NADH dehydrogenase complex?

I understand that in the absence of oxygen the functioning of cytochrome c oxidase stops because it is its substrate. However I don’t understand how stopping cytochrome c oxidase also stops the ...
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What triggers the switch between aerobic and anaerobic respiration?

I understand that when there is a shortage of oxygen cells convert the pyruvic acid from glycolysis to lactic acid to regenerate NAD+. What I don’t understand is how they switch to anaerobic ...
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Which complexes physically pump protons in photosynthesis?

The cytochrome b6f complex is often drawn as pumping protons, but then someone told me that actually there is no pumping, rather the Q cycle. According to this view, what actually moves the protons ...
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Is it possible to stop more/extra fat from being stored in the body?

I don't mean simply by restricting eating or upping the activities, but a way to basically stop the body from adding more fat on itself down on the bio level. For example, I'm not too knowledgeable on ...
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3 votes
1 answer
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How are electrons entering the electron transport chain in cellular respiration energised (excited)?

In photosynthesis, electrons are excited by light energy from the sun (photoactivated). How do they become excited in human cellular respiration? I believe it has something to do with NADH and ...
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4 votes
1 answer
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Can muscles work as brakes?

When I walk downhill I lose potential energy. If I descend 100m in, say, 10 minutes I lose potential energy at a rate of about 114J/s (114W). Where does the energy go? Not into kinetic energy ...
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Does our brain use up more ATP after smoking cannabis?

kind of an amateur here. If the firing of the neurons' signals uses up some ATP, and smoking cannabis makes them fire off more quickly, do our brains use up more ATP to sustain that rapid firing?
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1 vote
1 answer
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Where do Red Blood Cells use energy?

I know that RBCs use glycolysis of glucose to lactate to produce most of their energy, but, if they are just carrier cells, where do they use the energy?
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12 votes
2 answers
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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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Is intelligence correlated with neural calorie usage?

The human brain uses a lot of calories in comparison to other species, that is usually explained by referencing the intelligence disparity between Humans and other Animals. My question is how far does ...
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3 votes
3 answers
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Why is ATP hydrolysis to ADP, rather than ADP hydrolysis to AMP, used to drive biochemical reactions?

ADP has two phosphate groups, and can be hydrolysed to AMP in a reaction which involves a similar free energy change to that of hydrolysing ATP to ADP. Why is the latter reaction, rather than the ...
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2 votes
1 answer
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How are Mono and Diglycerides metabolized without the Free Fatty Acids of Triglycerides?

Having difficulty figuring out what the body does with ingested mono and diglycerides if the usual process of TAG metabolism includes the FFA released from the TAG returning to the MAG to recreate a ...
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3 votes
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How is ATP converted to adenosine?

I am familiar with adenosine diphosphate (ADP) and adenosine triphosphate (ATP), how one relates to the other, and how each is formed in cellular respiration and photosynthesis, but I am confused as ...
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1 vote
1 answer
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Can E. coli make pyruvate from acetate?

What pathway would E. coli use to make pyruvate from acetate? I have found several papers that refer to a possible mechanism that could move acetate to pyruvate via a three-step process: Step 1: ...
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Can plants yield two more molecules of ATP from glycolysis?

Since 2 ATP are used to convert glucose to glyceraldehyde 3-phosphate in glycolysis, can plants bypass this step of ATP investment since they produce glyceraldehyde 3-phosphate directly from the ...
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advantages of shivering in cold environments

When we feel cold, our the muscle tries to generate heat by shivering and the brown adipose tissue tries to generate heat by non-shivering methods. The muscle generates heat but also spends energy on ...
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Why is the separation of biochemical synthesis pathways safer and more economical?

During our first lecture of plant physiology, our teacher told us that the separation of biochemical synthesis pathways was advantageous because it was safer and more economical. The problem I got, ...
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