Questions tagged [metabolism]

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

Filter by
Sorted by
Tagged with
7
votes
2answers
453 views

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 ...
4
votes
1answer
142 views

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 ...
6
votes
1answer
648 views

Where does all the food go?

Food goes in, excrement come out. This seems obvious. But it seems like the mass of the excrement is less than the one of the food. Most people I asked answered: "There's a difference because it's ...
8
votes
1answer
1k views

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.
25
votes
4answers
144k views

What is a coupled reaction and why do cells couple reactions?

I was wondering what exactly a coupled reaction is and why cells couple them. I read the wikipedia article as well as several others, such as life.illinois.edu but I still don't get it. Could ...
3
votes
0answers
71 views

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'...
4
votes
1answer
120 views

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 ...
1
vote
1answer
100 views

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 ...
2
votes
0answers
31 views

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. ...
5
votes
1answer
349 views

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 ?
1
vote
1answer
117 views

Bilirubin metabolism and UGT1A1 inhibition in human vs. monkey?

In human UGT1A1 seems to be the only relevant enzyme to glucuronidate unconjugated bilirubin into excreted forms. Is the pathway the same for e.g. the Cynomolgus monkey (Macaca fascicularis) in vivo? ...
1
vote
0answers
212 views

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/...
5
votes
1answer
424 views

Why do humans circulate monosaccharides instead of disaccharides as in plants?

Plants transport food mostly in the form of disaccharides like sucrose but humans transport them in the form of a monosaccharide - glucose. What is the reason behind this ?
12
votes
3answers
899 views

How Does Green Tea Increase Metabolic Rate?

According to the article "Green Tea Supplementation Affects Body Weight, Lipids, and Lipid Peroxidation in Obese Subjects with Metabolic Syndrome", Green tea increases metabolism and fat loss: ...
1
vote
0answers
195 views

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 ...
8
votes
1answer
4k views

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 ...
6
votes
1answer
4k views

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?
1
vote
0answers
633 views

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
3
votes
1answer
113 views

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 ...
3
votes
2answers
16k views

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 ...
2
votes
1answer
3k views

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 ...
1
vote
2answers
1k views

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 ...
2
votes
1answer
609 views

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 ...
2
votes
1answer
55 views

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 ...
3
votes
2answers
2k views

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 ...
1
vote
0answers
52 views

How to determine the fastest metabolism ? [closed]

Which is the fastest metabolism ? Fructose metabolism or Glucose metabolism
1
vote
1answer
83 views

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 ...
2
votes
0answers
111 views

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.
2
votes
1answer
397 views

Are alpha-ketoglutarate and glutamate involved in all transamination reactions?

Is it true that for all biochemical transamination reactions, that alpha-ketoglutarate and glutamate serve as the amino group acceptor and donor, respectively? If this is true, then is it safe to ...
4
votes
2answers
384 views

Are there bacteria that respire anaerobically in aerobic conditions?

There are facultative anaerobic bacteria that switch to anaerobic respiration in an anaerobic state, but are there any organisms that would still perform anaerobic respiration even when shifted to ...
27
votes
1answer
39k views

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle

Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle? I originally thought that Krebs cycle was aerobic metabolism ...
4
votes
1answer
15k views

What are the differences between white and brown adipose tissue?

What are the differences between white and brown adipose tissue? Here are some that I have come across: ...
1
vote
1answer
173 views

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 ...
8
votes
2answers
10k views

Primary function of the enzyme lipoprotein lipase

I read here and here that the function of lipoprotein lipase is to facilitate fat uptake and storage in adipose tissue. Could anyone provide a slightly more expanded explanation, without going into ...
1
vote
1answer
2k views

Fate of Acetyl CoA in well fed state?

When we have eaten well and take fat rich diet then in this condition Acetyl CoA produced from fatty acid breakdown will be gone to storage in adipose tissue or not? If it will go for storage then why ...
4
votes
1answer
87 views

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 ...
1
vote
1answer
40 views

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 "...
1
vote
0answers
20 views

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? ...
0
votes
0answers
235 views

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:...
5
votes
2answers
380 views

Why doesn't Diabetes cause death by starvation?

The main cause for diabetes is lack of insulin in the body. Insulin is the hormone that allows body cells to absorb glucose from the blood. With out insulin, the body cells can't get glucose from the ...
7
votes
2answers
2k views

Does the brain and the body use the same energy source (glucose/ATP)?

I've heard that the brain consumes quite a lot of oxygen and energy, compared to the rest of the body. What I'm interested in is if this is the kind of energy and oxygen that the rest of the body ...
2
votes
1answer
2k views

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 ...
9
votes
1answer
2k views

How can haired mammals synthesize vitamin D?

The human body can synthesize vitamin D in the skin from cholesterol, when sun exposure is adequate. But how can haired mammals do it? Do not they need it?
4
votes
2answers
102 views

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,...
3
votes
1answer
975 views

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? ...
3
votes
1answer
71 views

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 ...
4
votes
2answers
180 views

Where do plants obtain the metal ions needed for biological processes?

Enzymes employ metal ions (e.g. Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn) for catalysing certain reactions. Let's consider planting a seed. Where will it obtain these metal ions from? Just from water?
3
votes
3answers
948 views

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 ...
1
vote
0answers
128 views

Insulin and leptin action on Anorexigenic Neurons in Hypothalamus?

Receptors for Insulin are present on liver, adipose tissue and muscles. In addition, there are Insulin Receptors present in arcuate nucleus of hypothalamus, which influences anorexogenic neurons ...
5
votes
1answer
124 views

Cellular demand for antioxidants

Antioxidants such as ascorbate and glutathione serve to inactivate radicals and counteract spontaneous oxidation reactions, such as unwanted disulfide bonds in proteins. These systems are cycles, ...