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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Where is the source of H+ in the matrix that will be pumped during the electron transfer system? Where does the OH generated at that time go?
In the electron transfer system, it has been mentioned in prior questions that complexes I, III, and IV are proton pumps and that these pumps pump protons from the matrix into the intermembrane space.
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Fate of GTP produced in the TCA cycle
As someone already mentioned in one of the following questions, the TCA circuit generates GTP in addition to NADH and FADH2. The fate of NADH and FADH2 is clear: they are used to pump protons in the ...
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Is the "endo-" prefix in "endotherm" inconsistent/opposite to its use in "endothermic reaction"?
It seems to me that the "endo-" in the biology term "endotherm" is opposite to the "endo-" in the chemistry term "endothermic reaction." Is that the case?
As I ...
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Why is sport healthy if high metabolism decreases life expectancy?
There is something that appears as a contradiction to a newbie like me.
Sport is widely recognized as healthy and recommended by medical experts.
Metabolic rate is inversely correlated with lifespan....
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How does mitochondrial uncoupling enhance performance in muscle cells?
As far aas I understand, in mitochondria, the citric acid cycle breaks down fatty acid or glucose to produce NADH and FADH2, which are then utilized by Complexes I through IV to generate a proton ...
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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 ...
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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&...
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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 ...
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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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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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How does the energy we get from food transform into mechanical motion at the cellular level?
I am curious how, food broken down into glucose powers the movement of proteins in our cells (e.g., in muscle fibers for example).
Is the thermal energy converted to kinetic energy somehow?
As a ...
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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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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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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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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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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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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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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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