The set of biochemical reactions that sustain life by directly or indirectly affecting energy expenditure and/or storage, as well as the complete regulation of those reactions and the enzymes that catalyze them; including, hormonal, cell-signaling, and substrate level regulation.

learn more… | top users | synonyms

0
votes
0answers
22 views

Diffusion coefficients of glucose in mammal tissues?

Where can I find estimates/experimental measurements of the diffusion coefficient of glucose in mammal tissues? Specefically I mean the inter-cellular space. I'm not looking for a specific tissue, so ...
2
votes
3answers
7k views

Why do we weigh less in the morning?

At first I thought it may be related to physics. You know, in one half of the day, the gravity changes, and the scale shows a different weight than the other. Then at night, gravity intensifies, and ...
6
votes
2answers
200 views

At any given moment, how much energy is stored in the human body as ATP?

At any given moment, approximately how much energy is stored in the human body as ATP in the ADP-P-bond? This of course depends on what type of cell it is and the activity of the individual in ...
13
votes
2answers
2k views

Do birds emit infra-red radiation?

I'm an electronics engineering student and I am going to use a sensor that detects infra-red emitted by birds that invade rice paddies. Do birds emit infra-red radiation?
8
votes
2answers
9k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
0
votes
0answers
27 views

Is there any evidence to suggest that exercise reduces the side effects of caffeine?

I heard a friend say: I'm not drinking coffee this week. My body can only process the caffeine if I run at least 15km a week. I found this claim fascinating - that exercise temporarily ...
7
votes
1answer
82 views

About acetyl-coA in the Krebs Cycle of respiration

In respiration, Krebs cycle starts with acetyl coenzyme A which is made from pyruvate. However, it is said that the cycle keeps repeat it self with oxaloacetate turning back to citrate and cycle ...
0
votes
0answers
30 views

Can an inhibited enzyme be activated by an activator molecule binding to a second allosteric site?

Can the inhibition caused by a inhibitor molecule(ATP that attaches itself to an allosteric site of a subunit of the PFK-1) be reversed by the binding of an activator molecule (AMP that binds to an ...
1
vote
0answers
38 views

Why are carbohydrates the most common short-to-medium-term energy storage form in biology?

According to this table, gasoline has a specific energy noticeably higher than fat and more than twice that of carbohydrates; even short-chain hydrocarbons like ethanol and even methanol offer an ...
7
votes
1answer
105 views

How many, and how severe, are known single gene polymorphisms for obesity?

A fairly recent meta-analysis of studies examining the association between adult obesity and polymorphisms of the FTO gene (Peng et al., 2011). The paper looked at 59 studies and concluded that, "FTO ...
2
votes
1answer
110 views

Why would the citrulline content of the watermelon be so high?

Citrulline is a non-proteinogenic amino acid (that is, citrulline is an amino acid that is not coded for in mRNA), and it is an important metabolic intermediate in the Urea Cycle. The Urea Cycle is ...
1
vote
0answers
27 views

Can you change your gut microbiota by changing your diet? Would that affect calorie uptake?

I have seen peer-reviewed papers mentioning the daily changes in gut microbiota composition according to dietary changes. See for example this paper: http://genomebiology.com/2014/15/7/R89 My ...
4
votes
2answers
114 views

What's the point of glycolysis in fermentation?

In order to initiate glycolysis, 2 ATP are necessary. In the glycolytic process, you generate an additional 4 ATP, which results in a net gain of 2 ATP. If you don't undergo glycolysis, however, then ...
3
votes
2answers
553 views

Why would lactate be high in diabetics?

Why are lactate level high in diabetes? For example, type II diabetes are resistant to insulin. If those patients are insulin resistant their gluconeogenesis should be working at a high rate and, ...
0
votes
2answers
188 views

Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

Succinate dehydrogenase is attached to the inner mitochondrial membrane. All the other enzymes of the Krebs cycle are located within the matrix of mitochondria, though. In biological systems, there ...
1
vote
1answer
53 views

What is the energy source for adipocytes?

Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes?
3
votes
1answer
1k views

How are non-glucose sugars metabolized in the body?

In my biology book's section on disaccharide metabolism and glycolysis, it states that sugars other than glucose must be acted upon to enter glycolysis. Let's take sucrose as an example. Sucrose is ...
4
votes
1answer
75 views

Can the kidneys utilize ketone bodies for energy?

Ketone bodies are water-soluble and should pose no problem to the kidneys because of solubility. If the kidneys are able to utilize ketone bodies for energy, then they must express the enzyme ...
4
votes
1answer
359 views

How is ammonia removed from the colon?

“Lactulose is also used to reduce the amount of ammonia in the blood of patients with liver disease. It works by drawing ammonia from the blood into the colon where it is removed from the body.” ...
1
vote
0answers
25 views

Is there a way to quantify in vivo cholesterol transport rates?

I have always had trouble grasping the physiology of lipoprotein cholesterol transport. The "standard" description found in the literature is that liver synthesizes cholesterol which is carried in ...
2
votes
1answer
740 views

Why does NAD+ become reduced if it gains a hydrogen proton?

I've heard that $NAD^+$ gains a Hydrogen proton during glycolysis and the Krebs cycle and becomes reduced to $NADH$. However, isn't reduction when a molecule receives an electron? Maybe I've been ...
5
votes
0answers
46 views

Is high metabolism linked to high evolutionary turnover?

I recently read The Dinosaur Heresies by Robert T. Bakker, a 1986 popular science book presenting arguments for an active lifestyle and high metabolic rate in dinosaurs. One of the arguments that ...
1
vote
0answers
44 views

In glycolysis, what is the source of the electron that makes NAD+ into NADH instead of NADH+? [closed]

I looked at the formula for the glycolysis reaction. The overall reaction seems balanced, however, I don't see anything on the left hand side of the equation that would provides the electron to ...
0
votes
0answers
31 views

Why is alcohol purged from the body more slowly when we sleep?

It is a popular belief that when you get asleep after drinking alcohol, in the morning you have higher level in your blood than if you stayed awake the whole night. Is this true? If so, why? Is it ...
3
votes
1answer
76 views

By what mechanism is NADP+ converted to NADPH in Photosystem I? [closed]

Here is my current understanding: $\mathrm{NADP^{+}}$ takes 2 electrons from Ferredoxin at the end of the electron transport chain to generate $\mathrm{NADP^{-}}$. An $\mathrm{H^{+}}$ ion in the ...
1
vote
0answers
21 views

How are muscle fibre size and oxygen consumption related?

Does anyone know of a paper which correlates the muscle fibre size to oxygen consumption in mammals? I am trying to find a correlation between muscle fibre type, size and (absolute and specific) ...
9
votes
1answer
79 views

What is the effect of exendin on beta-cells?

Do you know if exendin, an analog of GLP-1 (glucagon like peptide-1), can be toxic for beta-cells? For example, what is the effect on INS1 or Min6 cells at a certain concentration or after 90 mins of ...
2
votes
2answers
82 views

Conversion and storage of glucose to glycogen

Why is excess glucose, synthesized to glycogen, stored only in limited amounts, as compared with lipids/triglycerides that are stored in our body? Why is mature glycogen arranged (polymerized) in 12 ...
7
votes
4answers
2k views

Why do obese people tire quickly?

Fat people have a large amount of calories (energy) stored, but I have noticed all time when they do physical activities they get tired fast in comparison to fit people - why does this happen?
14
votes
2answers
233 views

Relationship between our microbiome and personalized nutrition

Recently, it has been asked whether there are 'metabolic types' between humans that can benefit from a sort of personalized nutrition. One answer suggested that one discerning factor could be the ...
3
votes
2answers
105 views

Energy metabolism in Cancer cells

The TCA cycle intermediate Isocitrate dehydrogenase commonly undergoes point mutations in cancers. This allows IDH to reduce a-Ketogluterate to 2Hydoxygluterate, causing a reduction in pVHLs ability ...
7
votes
1answer
122 views

If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
1
vote
0answers
37 views

What is the actual function of HDLs and CETP?

I know that HDLs collect cholesterol from peripheral tissues and transport it back to the liver using SRB1 - Reverse cholesterol transport and dumping it in bile. So the tissue is producing some extra ...
2
votes
1answer
99 views

How does the pancreatic beta-cell know how much insulin to secrete in response to glucose?

How do $\ce\beta$-cells know how much glucose is in the blood? I know that when glucose enters a beta cell it triggers the cell to produce insulin. $\ce\beta$-cells trap glucose by converting it into ...
1
vote
2answers
66 views

What are the differences between carnitine forms?

I've heard of L-carnitine, acetyl L-carnitine and L-carnitine L-tartrate. What form(s) occur in meat? What form does the human body manufacture? Is L-carnitine just a shortened name for L-carnitine ...
2
votes
1answer
218 views

Why do mice have a higher metabolism?

Mice and other small animals have higher metabolic rate than humans. How does that happen on cellular level, if we look on one cell in the mouse body? What is it in this cell that will be ...
0
votes
0answers
17 views

Can a computer display work as a daylight lamp?

During winter time I often see advertisements for daylight lamps which are supposed to compensate for the lack of daylight in a winter season. The specs of such a daylight lap seems to be an LED ...
2
votes
2answers
43 views

Is there a known or quantifiable correlation between capsaicin and its effect on the body's metabolism?

I've often heard that spicy foods can speed up your metabolism, I presume, due to the capsaicin. Though I'm sure this is a minor effect - I doubt eating a pound of jalapenos a day will help me lose ...
8
votes
2answers
429 views

Can a living organism run on electricity?

Each time I'm too lazy too cook I think it'd be cool to be able to just plug myselt into an outlet. Yet I know it is not possible - I need amino acids and a lot of other stuff that electricity can't ...
1
vote
0answers
33 views

metabolic heat generation and exercise intensity

Is there a relationship between bio heat equation (found here) and exercise intensity as described here That is I am trying to include the effect from exercises to the tempertaure variation in skin. I ...
2
votes
1answer
62 views

Are there differences in energy of glucose isomers?

There are many isomers of glucose, including galactose and fructose. Do they have different chemical energy levels, and why? What makes galactose and fructose useful compared to glucose, and would ...
3
votes
2answers
524 views

When glucose production is low, the brain begins using ketoacids as energy… how does that work?

Can someone very generally describe how the brain consumes ketoacids/ketone bodies when blood glucose has been completely depleted?
3
votes
1answer
173 views

ATP utilized in Glycolysis vs. Gluconeogenesis

In glycolysis, the conversion of glucose to pyruvate results in a net gain of 2 ATP molecules. In gluconeogenesis however, the conversion of pyruvate back to glucose requires 6 ATP molecules. Why ...
3
votes
1answer
45 views

Why would growth hormone (somatotropin) cause both lipid AND glucose release?

GH increases lipolysis (lipid breakdown) and the release of fatty acids from adipocytes into the blood. Fatty acids then can be used as energy sources to drive chemical reactions, including ...
1
vote
0answers
52 views

How much energy would it cost to synthesize all cholesterol requirements de novo?

Imagine a scenario in which some person is unable to absorb any dietary cholesterol because of some intestinal mutation (for example). Thus, they have no cholesterol available from their diet for ...
2
votes
1answer
9k 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: ...
4
votes
0answers
118 views

Why are Mammals are unable to produce Essential Fatty Acids?

Why do we have to get them from our diet, and if they aren't taken in our diet we will face disease? Then why we don't have the enzymes which are require for EFA synthesis?
1
vote
0answers
69 views

Giving life to a dead person [closed]

Could anyone please tell me whether we can conclude that no body of a dead human being can get life since all chemical reactions are irreversible in our human body?
2
votes
0answers
26 views

Metabolic control theory: proof of the summation theorem?

I'm looking for a rigorous proof of the summation theorem of metabolic control theory. The only sources I find are the original papers by Kacser and Burns 1973 and Heinrich and Rapoport 1974, both of ...
1
vote
1answer
20 views

Does the location of the double bond in chlorins yield a distinct biological function?

Chlorins differ by the number of double bonds and their location. Chlorin has 20 pi electrons, whereas bacteriochlorin and isobacterichlorin have 18 pi electrons, but at different locations. Do ...