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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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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 do plants do Photosynthesis and then Aerobic Respiration? [duplicate]

Plants do Photosynthesis in order to convert sunlight energy into chemical energy. They first store energy in ATP + NADPH and then use those two compounds in order to create Glyceraldehyde 3-phosphate ...
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Adipose Cellularity and Energy Intake

Is it plausible to consider increasing adipocyte size as a causal factor predicting less energy intake in humans in conditions of energy balance. It is well known that higher fat mass (FM) predicts ...
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How to overcome the tiredness feeling which come after studying 60-90 minutes [closed]

I am preparing for a examination called JEE which have physics, chemistry and maths questions in it. I study in slots of 10 minutes, for the first 9 minutes I study and and than completely rest for 1 ...
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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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How many calories does a person consume when sitting at a computer per hour, depending on body weight?

Suppose a person weighing 75 kilograms does three activities: Sleeps Sits working at the computer Going home from work. I need to know how many calories his body will consume in each of these cases ...
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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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1answer
100 views

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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33 views

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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56 views

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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1answer
58 views

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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1answer
32 views

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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104 views

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 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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3answers
577 views

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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1answer
261 views

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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1answer
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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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1answer
209 views

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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28 views

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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207 views

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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Simplest known form of aerobic glycolysis

What is the simplest known way that an organism performs aerobic glycolysis? In other words, what is the simplest known way known to convert glucose into $\ce{H2O}$ and $\ce{CO2}$, other than by ...
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77 views

Is it possible to lose weight doing brain exercise?

According to this article human brain consume a comparable amount of energy with skeletal muscle. So is it possible to do some brain exercise (calculate something in mind etc.) instead of physical ...
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How can dehydrogenation steps in some biochemical pathways produce ATP?

Dehydrogenation reaction of alkanes is inherently endothermic as one removes two thermodynamically more stable C-H bonds and replaces it with one less stable C=C. Although the product is conjugated ...
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112 views

Evolution of the energy generating system in mitochondria

Both yeast and humans have mitochondria. Given that yeast have a much shorter time between generation I would expect evolution to have had more time to optimize mitochondria of yeast. The main ...
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447 views

What do different fermentation products have in common?

I met with the following question in my masters course: What do different fermentation products have in common? Thinking about this, I have difficulty in identifying the similarities between ...
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194 views

Does the energy from ATP hydrolysis vary among different cells?

I know that when ATP is hydrolyzed into ADP it gives 7.3 kcal/mol. The question is, does this value vary among different types of cells?
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Why is GTP, rather than ATP, used in nuclear transport?

Why is GTP used for nuclear transport and not ATP, given that ATP hydrolysis is used to drive most cellular energonic reactions?
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Reason for conversion of glucose to fructose in glycolysis

In glycolysis, glucose is converted to glucose 6-phosphate so it can not diffuse out of the membrane. Then it is converted to fructose 6-phosphate. Why is this? Perhaps it makes it less stable so it ...
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Is it possible to have life that feeds on thermal energy

On earth, as far a we know, there are two main ways that bacteria gain energy. First, there is Photosynthesis, the transition of light into chemical based energies such as ATP. Second, there are ...
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How did giant sauropods satisfy their daily energy needs, considering their relatively small mouths?

Gigantic sauropod dinosaurs had relatively small heads (and consequently small mouths) in comparison to their overall body mass. In the book "Dinosaur Odyssey: Fossil Threads in the Web of Life" (by ...
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Energy efficiency of muscles and animals as a whole

When human or animal do some work, they use energy from their food. What is known about overall efficiency of this process? Say a horse is turning a winch and does 10,000 kJ of work. How much more ...
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4k views

Breathing faster to lose (more) weight?

I understand that when the human body loses weight, the vast majority of that weight is lost as $CO_2$ (and a small bit is lost as water). I expect the predominant way $CO_2$ exits the body is through ...
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Is it a valid generalization that kinases catalyse reactions involving energy transfer and utilization?

The Wikipedia entry for kinase states that "a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules [such as ATP] to specific substrates". ...
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196 views

How do plants store energy by potassium battery?

Plants have a so-called potassium battery system for energy storage/conversation. Wikipedia only has a reference to a technical article. Can someone explain it in a layman's language (or refer to a ...
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Anabolic reactions and reaction energy

My textbook says, In general, the formation of a [chemical] bond releases energy and continues to state, Anabolic reactions (collectively called anabolism) link simple molecules to form more ...
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733 views

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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Quinone A, Quinone B, Ubiquinone, Plastoquinone: whats the difference?

I am getting very confused about this. My understanding so far is that ubiquinone is used as an electron (and proton) carrier in oxidative phosphorylation in the mitochondria whereas plastoquinone is ...
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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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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 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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Do all prokaryotes have ATP synthases and an electron transport chain?

I was looking this up and I'm wondering if so far I'm correct about the following: For the most part eukaryotes do aerobic respiration, which involves glycolysis, the Krebs cycle and oxidative ...
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How many protons are pumped out per pair of electrons from NADH in oxidative phosphorylation?

I have searched the web and found that 10 protons are suppose to get pumped out during the electron cycle, but i'm a bit confused. I'm trying to count, for every complex(1/3/4), the number of protons ...